SQLite

** The xDisconnect() virtual table method.
*/
static int fts3DisconnectMethod(sqlite3_vtab *pVtab){
  Fts3Table *p = (Fts3Table *)pVtab;
  int i;

  assert( p->nPendingData==0 );
  assert( p->pSegments==0 );

  /* Free any prepared statements held */
  for(i=0; i<SizeofArray(p->aStmt); i++){
    sqlite3_finalize(p->aStmt[i]);
  }
  for(i=0; i<p->nLeavesStmt; i++){
    sqlite3_finalize(p->aLeavesStmt[i]);
  }
  sqlite3_free(p->zSelectLeaves);
  sqlite3_free(p->zSegmentsTbl);
  sqlite3_free(p->aLeavesStmt);

  /* Invoke the tokenizer destructor to free the tokenizer. */
  p->pTokenizer->pModule->xDestroy(p->pTokenizer);

  sqlite3_free(p);
  return SQLITE_OK;
}

/*
** Construct one or more SQL statements from the format string given
** and then evaluate those statements.  The success code is writting
** and then evaluate those statements. The success code is written
** into *pRc.
**
** If *pRc is initially non-zero then this routine is a no-op.
*/
static void fts3DbExec(
  int *pRc,              /* Success code */
  sqlite3 *db,           /* Database in which to run SQL */

}


/*
** Invoke sqlite3_declare_vtab() to declare the schema for the FTS3 table
** passed as the first argument. This is done as part of the xConnect()
** and xCreate() methods.
**
** If *pRc is non-zero when this function is called, it is a no-op. 
** Otherwise, if an error occurs, an SQLite error code is stored in *pRc
** before returning.
*/
static int fts3DeclareVtab(Fts3Table *p){
  int i;                          /* Iterator variable */
  int rc;                         /* Return code */
  char *zSql;                     /* SQL statement passed to declare_vtab() */
  char *zCols;                    /* List of user defined columns */
static void fts3DeclareVtab(int *pRc, Fts3Table *p){
  if( *pRc==SQLITE_OK ){
    int i;                        /* Iterator variable */
    int rc;                       /* Return code */
    char *zSql;                   /* SQL statement passed to declare_vtab() */
    char *zCols;                  /* List of user defined columns */

  /* Create a list of user columns for the virtual table */
  zCols = sqlite3_mprintf("%Q, ", p->azColumn[0]);
  for(i=1; zCols && i<p->nColumn; i++){
    zCols = sqlite3_mprintf("%z%Q, ", zCols, p->azColumn[i]);
  }
    /* Create a list of user columns for the virtual table */
    zCols = sqlite3_mprintf("%Q, ", p->azColumn[0]);
    for(i=1; zCols && i<p->nColumn; i++){
      zCols = sqlite3_mprintf("%z%Q, ", zCols, p->azColumn[i]);
    }

  /* Create the whole "CREATE TABLE" statement to pass to SQLite */
  zSql = sqlite3_mprintf(
      "CREATE TABLE x(%s %Q HIDDEN, docid HIDDEN)", zCols, p->zName
  );
    /* Create the whole "CREATE TABLE" statement to pass to SQLite */
    zSql = sqlite3_mprintf(
        "CREATE TABLE x(%s %Q HIDDEN, docid HIDDEN)", zCols, p->zName
    );

  if( !zCols || !zSql ){
    rc = SQLITE_NOMEM;
  }else{
    rc = sqlite3_declare_vtab(p->db, zSql);
  }
    if( !zCols || !zSql ){
      rc = SQLITE_NOMEM;
    }else{
      rc = sqlite3_declare_vtab(p->db, zSql);
    }

  sqlite3_free(zSql);
  sqlite3_free(zCols);
  return rc;
    sqlite3_free(zSql);
    sqlite3_free(zCols);
    *pRc = rc;
  }
}

/*
** Create the backing store tables (%_content, %_segments and %_segdir)
** required by the FTS3 table passed as the only argument. This is done
** as part of the vtab xCreate() method.
**
** If the p->bHasDocsize boolean is true (indicating that this is an
** FTS4 table, not an FTS3 table) then also create the %_docsize and
** %_stat tables required by FTS4.
*/
static int fts3CreateTables(Fts3Table *p){
  int rc = SQLITE_OK;             /* Return code */
  int i;                          /* Iterator variable */
  char *zContentCols;             /* Columns of %_content table */
  sqlite3 *db = p->db;            /* The database connection */

  /* Create a list of user columns for the content table */
  if( p->bHasContent ){
    zContentCols = sqlite3_mprintf("docid INTEGER PRIMARY KEY");
    for(i=0; zContentCols && i<p->nColumn; i++){
      char *z = p->azColumn[i];
      zContentCols = sqlite3_mprintf("%z, 'c%d%q'", zContentCols, i, z);
    }
    if( zContentCols==0 ) rc = SQLITE_NOMEM;
  zContentCols = sqlite3_mprintf("docid INTEGER PRIMARY KEY");
  for(i=0; zContentCols && i<p->nColumn; i++){
    char *z = p->azColumn[i];
    zContentCols = sqlite3_mprintf("%z, 'c%d%q'", zContentCols, i, z);
  }
  if( zContentCols==0 ) rc = SQLITE_NOMEM;

    /* Create the content table */
    fts3DbExec(&rc, db, 
       "CREATE TABLE %Q.'%q_content'(%s)",
       p->zDb, p->zName, zContentCols
    );
    sqlite3_free(zContentCols);
  /* Create the content table */
  fts3DbExec(&rc, db, 
     "CREATE TABLE %Q.'%q_content'(%s)",
     p->zDb, p->zName, zContentCols
  );
  sqlite3_free(zContentCols);
  }
  /* Create other tables */
  fts3DbExec(&rc, db, 
      "CREATE TABLE %Q.'%q_segments'(blockid INTEGER PRIMARY KEY, block BLOB);",
      p->zDb, p->zName
  );
  fts3DbExec(&rc, db, 
      "CREATE TABLE %Q.'%q_segdir'("

    zDb, zName, zSuffix
  );    
  rc = sqlite3_exec(db, zSql, fts3TableExistsCallback, &res, 0);
  sqlite3_free(zSql);
  *pResult = (u8)(res & 0xff);
  if( rc!=SQLITE_ABORT ) *pRc = rc;
}

/*
** Store the current database page-size in bytes in p->nPgsz.
**
** If *pRc is non-zero when this function is called, it is a no-op. 
** Otherwise, if an error occurs, an SQLite error code is stored in *pRc
** before returning.
*/
static void fts3DatabasePageSize(int *pRc, Fts3Table *p){
  if( *pRc==SQLITE_OK ){
    int rc;                       /* Return code */
    char *zSql;                   /* SQL text "PRAGMA %Q.page_size" */
    sqlite3_stmt *pStmt;          /* Compiled "PRAGMA %Q.page_size" statement */
  
    zSql = sqlite3_mprintf("PRAGMA %Q.page_size", p->zDb);
    if( !zSql ){
      rc = SQLITE_NOMEM;
    }else{
      rc = sqlite3_prepare(p->db, zSql, -1, &pStmt, 0);
      if( rc==SQLITE_OK ){
        sqlite3_step(pStmt);
        p->nPgsz = sqlite3_column_int(pStmt, 0);
        rc = sqlite3_finalize(pStmt);
      }
    }
    assert( p->nPgsz>0 || rc!=SQLITE_OK );
    sqlite3_free(zSql);
    *pRc = rc;
  }
}

/*
** This function is the implementation of both the xConnect and xCreate
** methods of the FTS3 virtual table.
**
** The argv[] array contains the following:
**

    p->bHasDocsize = argv[0][3]=='4';
    rc = fts3CreateTables(p);
  }else{
    rc = SQLITE_OK;
    fts3TableExists(&rc, db, argv[1], argv[2], "_content", &p->bHasContent);
    fts3TableExists(&rc, db, argv[1], argv[2], "_docsize", &p->bHasDocsize);
  }
  if( rc!=SQLITE_OK ) goto fts3_init_out;

  /* Figure out the page-size for the database. This is required in order to
  ** estimate the cost of loading large doclists from the database (see 
  ** function sqlite3Fts3SegReaderCost() for details).
  */
  rc = fts3DeclareVtab(p);
  fts3DatabasePageSize(&rc, p);
  if( rc!=SQLITE_OK ) goto fts3_init_out;

  /* Declare the table schema to SQLite. */
  *ppVTab = &p->base;
  fts3DeclareVtab(&rc, p);

fts3_init_out:
  assert( p || (pTokenizer && rc!=SQLITE_OK) );
  if( rc!=SQLITE_OK ){
    if( p ){
      fts3DisconnectMethod((sqlite3_vtab *)p);
    }else{
      pTokenizer->pModule->xDestroy(pTokenizer);
    }
  }else{
    *ppVTab = &p->base;
  }
  return rc;
}

/*
** The xConnect() and xCreate() methods for the virtual table. All the
** work is done in function fts3InitVtab().

  return SQLITE_OK;
}

/*
** Close the cursor.  For additional information see the documentation
** on the xClose method of the virtual table interface.
*/
static int fulltextClose(sqlite3_vtab_cursor *pCursor){
static int fts3CloseMethod(sqlite3_vtab_cursor *pCursor){
  Fts3Cursor *pCsr = (Fts3Cursor *)pCursor;
  assert( ((Fts3Table *)pCsr->base.pVtab)->pSegments==0 );
  sqlite3_finalize(pCsr->pStmt);
  sqlite3Fts3ExprFree(pCsr->pExpr);
  sqlite3Fts3FreeDeferredTokens(pCsr);
  sqlite3_free(pCsr->aDoclist);
  sqlite3_free(pCsr->aMatchinfo);
  sqlite3_free(pCsr);
  return SQLITE_OK;
}

/*

    }
  }else{
    return SQLITE_OK;
  }
}

/*
** Advance the cursor to the next row in the %_content table that
** matches the search criteria.  For a MATCH search, this will be
** the next row that matches.  For a full-table scan, this will be
** simply the next row in the %_content table.  For a docid lookup,
** this routine simply sets the EOF flag.
** This function is used to process a single interior node when searching
** a b-tree for a term or term prefix. The node data is passed to this 
** function via the zNode/nNode parameters. The term to search for is
** passed in zTerm/nTerm.
**
** If piFirst is not NULL, then this function sets *piFirst to the blockid
** of the child node that heads the sub-tree that may contain the term.
**
** If piLast is not NULL, then *piLast is set to the right-most child node
** that heads a sub-tree that may contain a term for which zTerm/nTerm is
** a prefix.
**
** Return SQLITE_OK if nothing goes wrong.  SQLITE_OK is returned
** If an OOM error occurs, SQLITE_NOMEM is returned. Otherwise, SQLITE_OK.
** even if we reach end-of-file.  The fts3EofMethod() will be called
** subsequently to determine whether or not an EOF was hit.
*/
static int fts3NextMethod(sqlite3_vtab_cursor *pCursor){
static int fts3ScanInteriorNode(
  Fts3Table *p,                   /* Virtual table handle */
  const char *zTerm,              /* Term to select leaves for */
  int nTerm,                      /* Size of term zTerm in bytes */
  const char *zNode,              /* Buffer containing segment interior node */
  int nNode,                      /* Size of buffer at zNode */
  sqlite3_int64 *piFirst,         /* OUT: Selected child node */
  sqlite3_int64 *piLast           /* OUT: Selected child node */
){
  int rc = SQLITE_OK;             /* Return code */
  const char *zCsr = zNode;       /* Cursor to iterate through node */
  const char *zEnd = &zCsr[nNode];/* End of interior node buffer */
  char *zBuffer = 0;              /* Buffer to load terms into */
  int nAlloc = 0;                 /* Size of allocated buffer */
  int isFirstTerm = 1;            /* True when processing first term on page */
  sqlite3_int64 iChild;           /* Block id of child node to descend to */
  Fts3Cursor *pCsr = (Fts3Cursor *)pCursor;

  if( pCsr->aDoclist==0 ){
    if( SQLITE_ROW!=sqlite3_step(pCsr->pStmt) ){
      pCsr->isEof = 1;
      rc = sqlite3_reset(pCsr->pStmt);
    }
  }else if( pCsr->pNextId>=&pCsr->aDoclist[pCsr->nDoclist] ){
    pCsr->isEof = 1;
  }else{
    sqlite3_reset(pCsr->pStmt);
    fts3GetDeltaVarint(&pCsr->pNextId, &pCsr->iPrevId);
    pCsr->isRequireSeek = 1;

  /* Skip over the 'height' varint that occurs at the start of every 
  ** interior node. Then load the blockid of the left-child of the b-tree
  ** node into variable iChild.  */
  zCsr += sqlite3Fts3GetVarint(zCsr, &iChild);
  zCsr += sqlite3Fts3GetVarint(zCsr, &iChild);
  
  while( zCsr<zEnd && (piFirst || piLast) ){
    int cmp;                      /* memcmp() result */
    int nSuffix;                  /* Size of term suffix */
    int nPrefix = 0;              /* Size of term prefix */
    int nBuffer;                  /* Total term size */
  
    /* Load the next term on the node into zBuffer. Use realloc() to expand
    ** the size of zBuffer if required.  */
    if( !isFirstTerm ){
      zCsr += sqlite3Fts3GetVarint32(zCsr, &nPrefix);
    }
    isFirstTerm = 0;
    zCsr += sqlite3Fts3GetVarint32(zCsr, &nSuffix);
    if( nPrefix+nSuffix>nAlloc ){
      char *zNew;
      nAlloc = (nPrefix+nSuffix) * 2;
      zNew = (char *)sqlite3_realloc(zBuffer, nAlloc);
      if( !zNew ){
        sqlite3_free(zBuffer);
        return SQLITE_NOMEM;
      }
      zBuffer = zNew;
    }
    memcpy(&zBuffer[nPrefix], zCsr, nSuffix);
    nBuffer = nPrefix + nSuffix;
    zCsr += nSuffix;

    /* Compare the term we are searching for with the term just loaded from
    ** the interior node. If the specified term is greater than or equal
    ** to the term from the interior node, then all terms on the sub-tree 
    ** headed by node iChild are smaller than zTerm. No need to search 
    ** iChild.
    **
    ** If the interior node term is larger than the specified term, then
    ** the tree headed by iChild may contain the specified term.
    */
    cmp = memcmp(zTerm, zBuffer, (nBuffer>nTerm ? nTerm : nBuffer));
    if( piFirst && (cmp<0 || (cmp==0 && nBuffer>nTerm)) ){
      *piFirst = iChild;
      piFirst = 0;
    }

    if( piLast && cmp<0 ){
      *piLast = iChild;
      piLast = 0;
    }

    iChild++;
  };

  if( piFirst ) *piFirst = iChild;
  if( piLast ) *piLast = iChild;
    pCsr->isMatchinfoNeeded = 1;
  }

  sqlite3_free(zBuffer);
  return rc;
}


/*
** The buffer pointed to by argument zNode (size nNode bytes) contains the
** root node of a b-tree segment. The segment is guaranteed to be at least
** one level high (i.e. the root node is not also a leaf). If successful,
** this function locates the leaf node of the segment that may contain the 
** term specified by arguments zTerm and nTerm and writes its block number 
** to *piLeaf.
** The buffer pointed to by argument zNode (size nNode bytes) contains an
** interior node of a b-tree segment. The zTerm buffer (size nTerm bytes)
** contains a term. This function searches the sub-tree headed by the zNode
** node for the range of leaf nodes that may contain the specified term
** or terms for which the specified term is a prefix.
**
** If piLeaf is not NULL, then *piLeaf is set to the blockid of the 
** left-most leaf node in the tree that may contain the specified term.
** If piLeaf2 is not NULL, then *piLeaf2 is set to the blockid of the
** right-most leaf node that may contain a term for which the specified
** term is a prefix.
**
** It is possible that the returned leaf node does not contain the specified
** term. However, if the segment does contain said term, it is stored on
** the identified leaf node. Because this function only inspects interior
** segment nodes (and never loads leaf nodes into memory), it is not possible
** It is possible that the range of returned leaf nodes does not contain 
** the specified term or any terms for which it is a prefix. However, if the 
** segment does contain any such terms, they are stored within the identified
** range. Because this function only inspects interior segment nodes (and
** never loads leaf nodes into memory), it is not possible to be sure.
** to be sure.
**
** If an error occurs, an error code other than SQLITE_OK is returned.
*/ 
static int fts3SelectLeaf(
  Fts3Table *p,                   /* Virtual table handle */
  const char *zTerm,              /* Term to select leaves for */
  int nTerm,                      /* Size of term zTerm in bytes */
  const char *zNode,              /* Buffer containing segment interior node */
  int nNode,                      /* Size of buffer at zNode */
  sqlite3_int64 *piLeaf           /* Selected leaf node */
  sqlite3_int64 *piLeaf,          /* Selected leaf node */
  sqlite3_int64 *piLeaf2          /* Selected leaf node */
){
  int rc = SQLITE_OK;             /* Return code */
  int rc;                         /* Return code */
  const char *zCsr = zNode;       /* Cursor to iterate through node */
  const char *zEnd = &zCsr[nNode];/* End of interior node buffer */
  char *zBuffer = 0;              /* Buffer to load terms into */
  int nAlloc = 0;                 /* Size of allocated buffer */
  int iHeight;                    /* Height of this node in tree */

  while( 1 ){
  assert( piLeaf || piLeaf2 );
    int isFirstTerm = 1;          /* True when processing first term on page */
    int iHeight;                  /* Height of this node in tree */
    sqlite3_int64 iChild;         /* Block id of child node to descend to */
    int nBlock;                   /* Size of child node in bytes */

    zCsr += sqlite3Fts3GetVarint32(zCsr, &iHeight);
  sqlite3Fts3GetVarint32(zNode, &iHeight);
    zCsr += sqlite3Fts3GetVarint(zCsr, &iChild);
  
  rc = fts3ScanInteriorNode(p, zTerm, nTerm, zNode, nNode, piLeaf, piLeaf2);
  assert( !piLeaf2 || !piLeaf || rc!=SQLITE_OK || (*piLeaf<=*piLeaf2) );

    while( zCsr<zEnd ){
      int cmp;                    /* memcmp() result */
      int nSuffix;                /* Size of term suffix */
      int nPrefix = 0;            /* Size of term prefix */
      int nBuffer;                /* Total term size */
  
  if( rc==SQLITE_OK && iHeight>1 ){
    char *zBlob = 0;              /* Blob read from %_segments table */
    int nBlob;                    /* Size of zBlob in bytes */

      /* Load the next term on the node into zBuffer */
      if( !isFirstTerm ){
        zCsr += sqlite3Fts3GetVarint32(zCsr, &nPrefix);
    if( piLeaf && piLeaf2 && (*piLeaf!=*piLeaf2) ){
      rc = sqlite3Fts3ReadBlock(p, *piLeaf, &zBlob, &nBlob);
      }
      isFirstTerm = 0;
      zCsr += sqlite3Fts3GetVarint32(zCsr, &nSuffix);
      if( nPrefix+nSuffix>nAlloc ){
        char *zNew;
        nAlloc = (nPrefix+nSuffix) * 2;
        zNew = (char *)sqlite3_realloc(zBuffer, nAlloc);
        if( !zNew ){
          sqlite3_free(zBuffer);
          return SQLITE_NOMEM;
        }
        zBuffer = zNew;
      }
      if( rc==SQLITE_OK ){
        rc = fts3SelectLeaf(p, zTerm, nTerm, zBlob, nBlob, piLeaf, 0);
      }
      sqlite3_free(zBlob);
      piLeaf = 0;
      zBlob = 0;
    }
      memcpy(&zBuffer[nPrefix], zCsr, nSuffix);
      nBuffer = nPrefix + nSuffix;
      zCsr += nSuffix;
  

      /* Compare the term we are searching for with the term just loaded from
      ** the interior node. If the specified term is greater than or equal
      ** to the term from the interior node, then all terms on the sub-tree 
      ** headed by node iChild are smaller than zTerm. No need to search 
      ** iChild.
      **
      ** If the interior node term is larger than the specified term, then
      ** the tree headed by iChild may contain the specified term.
      */
      cmp = memcmp(zTerm, zBuffer, (nBuffer>nTerm ? nTerm : nBuffer));
      if( cmp<0 || (cmp==0 && nBuffer>nTerm) ) break;
    if( rc==SQLITE_OK ){
      iChild++;
    };

      rc = sqlite3Fts3ReadBlock(p, piLeaf ? *piLeaf : *piLeaf2, &zBlob, &nBlob);
    }
    /* If (iHeight==1), the children of this interior node are leaves. The
    ** specified term may be present on leaf node iChild.
    */
    if( iHeight==1 ){
      *piLeaf = iChild;
    if( rc==SQLITE_OK ){
      rc = fts3SelectLeaf(p, zTerm, nTerm, zBlob, nBlob, piLeaf, piLeaf2);
      break;
    }
    sqlite3_free(zBlob);

  }
    /* Descend to interior node iChild. */
    rc = sqlite3Fts3ReadBlock(p, iChild, &zCsr, &nBlock);
    if( rc!=SQLITE_OK ) break;
    zEnd = &zCsr[nBlock];
  }

  sqlite3_free(zBuffer);
  return rc;
}

/*
** This function is used to create delta-encoded serialized lists of FTS3 
** varints. Each call to this function appends a single varint to a list.
*/

  *pp = p;
  *pp1 = p1 + 1;
  *pp2 = p2 + 1;
}

/*
** nToken==1 searches for adjacent positions.
**
** This function is used to merge two position lists into one. When it is
** called, *pp1 and *pp2 must both point to position lists. A position-list is
** the part of a doclist that follows each document id. For example, if a row
** contains:
**
**     'a b c'|'x y z'|'a b b a'
**
** Then the position list for this row for token 'b' would consist of:
**
**     0x02 0x01 0x02 0x03 0x03 0x00
**
** When this function returns, both *pp1 and *pp2 are left pointing to the
** byte following the 0x00 terminator of their respective position lists.
**
** If isSaveLeft is 0, an entry is added to the output position list for 
** each position in *pp2 for which there exists one or more positions in
** *pp1 so that (pos(*pp2)>pos(*pp1) && pos(*pp2)-pos(*pp1)<=nToken). i.e.
** when the *pp1 token appears before the *pp2 token, but not more than nToken
** slots before it.
*/
static int fts3PoslistPhraseMerge(
  char **pp,                      /* Output buffer */
  char **pp,                      /* IN/OUT: Preallocated output buffer */
  int nToken,                     /* Maximum difference in token positions */
  int isSaveLeft,                 /* Save the left position */
  int isExact,                    /* If *pp1 is exactly nTokens before *pp2 */
  char **pp1,                     /* Left input list */
  char **pp2                      /* Right input list */
  char **pp1,                     /* IN/OUT: Left input list */
  char **pp2                      /* IN/OUT: Right input list */
){
  char *p = (pp ? *pp : 0);
  char *p1 = *pp1;
  char *p2 = *pp2;

  int iCol1 = 0;
  int iCol2 = 0;

  /* Never set both isSaveLeft and isExact for the same invocation. */
  assert( isSaveLeft==0 || isExact==0 );

  assert( *p1!=0 && *p2!=0 );
  if( *p1==POS_COLUMN ){ 
    p1++;
    p1 += sqlite3Fts3GetVarint32(p1, &iCol1);
  }
  if( *p2==POS_COLUMN ){ 
    p2++;

      assert( *p1!=POS_END && *p1!=POS_COLUMN );
      assert( *p2!=POS_END && *p2!=POS_COLUMN );
      fts3GetDeltaVarint(&p1, &iPos1); iPos1 -= 2;
      fts3GetDeltaVarint(&p2, &iPos2); iPos2 -= 2;

      while( 1 ){
        if( iPos2==iPos1+nToken 
        if( iPos2>iPos1 && iPos2<=iPos1+nToken ){
         || (isExact==0 && iPos2>iPos1 && iPos2<=iPos1+nToken) 
        ){
          sqlite3_int64 iSave;
          if( !pp ){
            fts3PoslistCopy(0, &p2);
            fts3PoslistCopy(0, &p1);
            *pp1 = p1;
            *pp2 = p2;
            return 1;

  char **pp1,                     /* IN/OUT: Left input list */
  char **pp2                      /* IN/OUT: Right input list */
){
  char *p1 = *pp1;
  char *p2 = *pp2;

  if( !pp ){
    if( fts3PoslistPhraseMerge(0, nRight, 0, pp1, pp2) ) return 1;
    if( fts3PoslistPhraseMerge(0, nRight, 0, 0, pp1, pp2) ) return 1;
    *pp1 = p1;
    *pp2 = p2;
    return fts3PoslistPhraseMerge(0, nLeft, 0, pp2, pp1);
    return fts3PoslistPhraseMerge(0, nLeft, 0, 0, pp2, pp1);
  }else{
    char *pTmp1 = aTmp;
    char *pTmp2;
    char *aTmp2;
    int res = 1;

    fts3PoslistPhraseMerge(&pTmp1, nRight, 0, pp1, pp2);
    fts3PoslistPhraseMerge(&pTmp1, nRight, 0, 0, pp1, pp2);
    aTmp2 = pTmp2 = pTmp1;
    *pp1 = p1;
    *pp2 = p2;
    fts3PoslistPhraseMerge(&pTmp2, nLeft, 1, pp2, pp1);
    fts3PoslistPhraseMerge(&pTmp2, nLeft, 1, 0, pp2, pp1);
    if( pTmp1!=aTmp && pTmp2!=aTmp2 ){
      fts3PoslistMerge(pp, &aTmp, &aTmp2);
    }else if( pTmp1!=aTmp ){
      fts3PoslistCopy(pp, &aTmp);
    }else if( pTmp2!=aTmp2 ){
      fts3PoslistCopy(pp, &aTmp2);
    }else{

  int nParam1,                    /* Used by MERGE_NEAR and MERGE_POS_NEAR */
  int nParam2,                    /* Used by MERGE_NEAR and MERGE_POS_NEAR */
  char *aBuffer,                  /* Pre-allocated output buffer */
  int *pnBuffer,                  /* OUT: Bytes written to aBuffer */
  char *a1,                       /* Buffer containing first doclist */
  int n1,                         /* Size of buffer a1 */
  char *a2,                       /* Buffer containing second doclist */
  int n2                          /* Size of buffer a2 */
  int n2,                         /* Size of buffer a2 */
  int *pnDoc                      /* OUT: Number of docids in output */
){
  sqlite3_int64 i1 = 0;
  sqlite3_int64 i2 = 0;
  sqlite3_int64 iPrev = 0;

  char *p = aBuffer;
  char *p1 = a1;
  char *p2 = a2;
  char *pEnd1 = &a1[n1];
  char *pEnd2 = &a2[n2];
  int nDoc = 0;

  assert( mergetype==MERGE_OR     || mergetype==MERGE_POS_OR 
       || mergetype==MERGE_AND    || mergetype==MERGE_NOT
       || mergetype==MERGE_PHRASE || mergetype==MERGE_POS_PHRASE
       || mergetype==MERGE_NEAR   || mergetype==MERGE_POS_NEAR
  );

    case MERGE_AND:
      while( p1 && p2 ){
        if( i1==i2 ){
          fts3PutDeltaVarint(&p, &iPrev, i1);
          fts3GetDeltaVarint2(&p1, pEnd1, &i1);
          fts3GetDeltaVarint2(&p2, pEnd2, &i2);
          nDoc++;
        }else if( i1<i2 ){
          fts3GetDeltaVarint2(&p1, pEnd1, &i1);
        }else{
          fts3GetDeltaVarint2(&p2, pEnd2, &i2);
        }
      }
      break;

    case MERGE_PHRASE: {
      char **ppPos = (mergetype==MERGE_PHRASE ? 0 : &p);
      while( p1 && p2 ){
        if( i1==i2 ){
          char *pSave = p;
          sqlite3_int64 iPrevSave = iPrev;
          fts3PutDeltaVarint(&p, &iPrev, i1);
          if( 0==fts3PoslistPhraseMerge(ppPos, 1, 0, &p1, &p2) ){
          if( 0==fts3PoslistPhraseMerge(ppPos, nParam1, 0, 1, &p1, &p2) ){
            p = pSave;
            iPrev = iPrevSave;
          }else{
            nDoc++;
          }
          fts3GetDeltaVarint2(&p1, pEnd1, &i1);
          fts3GetDeltaVarint2(&p2, pEnd2, &i2);
        }else if( i1<i2 ){
          fts3PoslistCopy(0, &p1);
          fts3GetDeltaVarint2(&p1, pEnd1, &i1);
        }else{

        }
      }
      sqlite3_free(aTmp);
      break;
    }
  }

  if( pnDoc ) *pnDoc = nDoc;
  *pnBuffer = (int)(p-aBuffer);
  return SQLITE_OK;
}

/* 
** A pointer to an instance of this structure is used as the context 
** argument to sqlite3Fts3SegReaderIterate()

  ** into a single doclist.
  */
  for(i=0; i<SizeofArray(pTS->aaOutput); i++){
    if( pTS->aaOutput[i] ){
      if( !aOut ){
        aOut = pTS->aaOutput[i];
        nOut = pTS->anOutput[i];
        pTS->aaOutput[0] = 0;
        pTS->aaOutput[i] = 0;
      }else{
        int nNew = nOut + pTS->anOutput[i];
        char *aNew = sqlite3_malloc(nNew);
        if( !aNew ){
          sqlite3_free(aOut);
          return SQLITE_NOMEM;
        }
        fts3DoclistMerge(mergetype, 0, 0,
            aNew, &nNew, pTS->aaOutput[i], pTS->anOutput[i], aOut, nOut
            aNew, &nNew, pTS->aaOutput[i], pTS->anOutput[i], aOut, nOut, 0
        );
        sqlite3_free(pTS->aaOutput[i]);
        sqlite3_free(aOut);
        pTS->aaOutput[i] = 0;
        aOut = aNew;
        nOut = nNew;
      }

      aNew = sqlite3_malloc(nNew);
      if( !aNew ){
        if( aMerge!=aDoclist ){
          sqlite3_free(aMerge);
        }
        return SQLITE_NOMEM;
      }
      fts3DoclistMerge(mergetype, 0, 0,
          aNew, &nNew, pTS->aaOutput[iOut], pTS->anOutput[iOut], aMerge, nMerge
      fts3DoclistMerge(mergetype, 0, 0, aNew, &nNew, 
          pTS->aaOutput[iOut], pTS->anOutput[iOut], aMerge, nMerge, 0
      );

      if( iOut>0 ) sqlite3_free(aMerge);
      sqlite3_free(pTS->aaOutput[iOut]);
      pTS->aaOutput[iOut] = 0;

      aMerge = aNew;
      nMerge = nNew;
      if( (iOut+1)==SizeofArray(pTS->aaOutput) ){
        pTS->aaOutput[iOut] = aMerge;
        pTS->anOutput[iOut] = nMerge;
      }
    }
  }
  return SQLITE_OK;
}

static int fts3DeferredTermSelect(
  Fts3DeferredToken *pToken,      /* Phrase token */
  int isTermPos,                  /* True to include positions */
  int *pnOut,                     /* OUT: Size of list */
  char **ppOut                    /* OUT: Body of list */
){
  char *aSource;
  int nSource;

  aSource = sqlite3Fts3DeferredDoclist(pToken, &nSource);
  if( !aSource ){
    *pnOut = 0;
    *ppOut = 0;
  }else if( isTermPos ){
    *ppOut = sqlite3_malloc(nSource);
    if( !*ppOut ) return SQLITE_NOMEM;
    memcpy(*ppOut, aSource, nSource);
    *pnOut = nSource;
  }else{
    sqlite3_int64 docid;
    *pnOut = sqlite3Fts3GetVarint(aSource, &docid);
    *ppOut = sqlite3_malloc(*pnOut);
    if( !*ppOut ) return SQLITE_NOMEM;
    sqlite3Fts3PutVarint(*ppOut, docid);
  }

  return SQLITE_OK;
}

/*
** An Fts3SegReaderArray is used to store an array of Fts3SegReader objects.
** Elements are added to the array using fts3SegReaderArrayAdd(). 
*/
struct Fts3SegReaderArray {
  int nSegment;                   /* Number of valid entries in apSegment[] */
  int nAlloc;                     /* Allocated size of apSegment[] */
  int nCost;                      /* The cost of executing SegReaderIterate() */
  Fts3SegReader *apSegment[1];    /* Array of seg-reader objects */
};


/*
** Free an Fts3SegReaderArray object. Also free all seg-readers in the
** array (using sqlite3Fts3SegReaderFree()).
*/
static void fts3SegReaderArrayFree(Fts3SegReaderArray *pArray){
  if( pArray ){
    int i;
    for(i=0; i<pArray->nSegment; i++){
      sqlite3Fts3SegReaderFree(0, pArray->apSegment[i]);
    }
    sqlite3_free(pArray);
  }
}

static int fts3SegReaderArrayAdd(
  Fts3SegReaderArray **ppArray, 
  Fts3SegReader *pNew
){
  Fts3SegReaderArray *pArray = *ppArray;

  if( !pArray || pArray->nAlloc==pArray->nSegment ){
    int nNew = (pArray ? pArray->nAlloc+16 : 16);
    pArray = (Fts3SegReaderArray *)sqlite3_realloc(pArray, 
        sizeof(Fts3SegReaderArray) + (nNew-1) * sizeof(Fts3SegReader*)
    );
    if( !pArray ){
      sqlite3Fts3SegReaderFree(0, pNew);
      return SQLITE_NOMEM;
    }
    if( nNew==16 ){
      pArray->nSegment = 0;
      pArray->nCost = 0;
    }
    pArray->nAlloc = nNew;
    *ppArray = pArray;
  }

  pArray->apSegment[pArray->nSegment++] = pNew;
  return SQLITE_OK;
}

static int fts3TermSegReaderArray(
  Fts3Cursor *pCsr,               /* Virtual table cursor handle */
  const char *zTerm,              /* Term to query for */
  int nTerm,                      /* Size of zTerm in bytes */
  int isPrefix,                   /* True for a prefix search */
  Fts3SegReaderArray **ppArray    /* OUT: Allocated seg-reader array */
){
  Fts3Table *p = (Fts3Table *)pCsr->base.pVtab;
  int rc;                         /* Return code */
  Fts3SegReaderArray *pArray = 0; /* Array object to build */
  Fts3SegReader *pReader = 0;     /* Seg-reader to add to pArray */ 
  sqlite3_stmt *pStmt = 0;        /* SQL statement to scan %_segdir table */
  int iAge = 0;                   /* Used to assign ages to segments */

  /* Allocate a seg-reader to scan the pending terms, if any. */
  rc = sqlite3Fts3SegReaderPending(p, zTerm, nTerm, isPrefix, &pReader);
  if( rc==SQLITE_OK && pReader ) {
    rc = fts3SegReaderArrayAdd(&pArray, pReader);
  }

  /* Loop through the entire %_segdir table. For each segment, create a
  ** Fts3SegReader to iterate through the subset of the segment leaves
  ** that may contain a term that matches zTerm/nTerm. For non-prefix
  ** searches, this is always a single leaf. For prefix searches, this
  ** may be a contiguous block of leaves.
  */
  if( rc==SQLITE_OK ){
    rc = sqlite3Fts3AllSegdirs(p, &pStmt);
  }
  while( rc==SQLITE_OK && SQLITE_ROW==(rc = sqlite3_step(pStmt)) ){
    Fts3SegReader *pNew = 0;
    int nRoot = sqlite3_column_bytes(pStmt, 4);
    char const *zRoot = sqlite3_column_blob(pStmt, 4);
    if( sqlite3_column_int64(pStmt, 1)==0 ){
      /* The entire segment is stored on the root node (which must be a
      ** leaf). Do not bother inspecting any data in this case, just
      ** create a Fts3SegReader to scan the single leaf. 
      */
      rc = sqlite3Fts3SegReaderNew(p, iAge, 0, 0, 0, zRoot, nRoot, &pNew);
    }else{
      sqlite3_int64 i1;           /* First leaf that may contain zTerm */
      sqlite3_int64 i2;           /* Final leaf that may contain zTerm */
      rc = fts3SelectLeaf(p, zTerm, nTerm, zRoot, nRoot, &i1, (isPrefix?&i2:0));
      if( isPrefix==0 ) i2 = i1;
      if( rc==SQLITE_OK ){
        rc = sqlite3Fts3SegReaderNew(p, iAge, i1, i2, 0, 0, 0, &pNew);
      }
    }
    assert( (pNew==0)==(rc!=SQLITE_OK) );

    /* If a new Fts3SegReader was allocated, add it to the array. */
    if( rc==SQLITE_OK ){
      rc = fts3SegReaderArrayAdd(&pArray, pNew);
    }
    if( rc==SQLITE_OK ){
      rc = sqlite3Fts3SegReaderCost(pCsr, pNew, &pArray->nCost);
    }
    iAge++;
  }

  if( rc==SQLITE_DONE ){
    rc = sqlite3_reset(pStmt);
  }else{
    sqlite3_reset(pStmt);
  }
  if( rc!=SQLITE_OK ){
    fts3SegReaderArrayFree(pArray);
    pArray = 0;
  }
  *ppArray = pArray;
  return rc;
}

/*
** This function retreives the doclist for the specified term (or term
** prefix) from the database. 
**
** The returned doclist may be in one of two formats, depending on the 
** value of parameter isReqPos. If isReqPos is zero, then the doclist is
** a sorted list of delta-compressed docids (a bare doclist). If isReqPos
** is non-zero, then the returned list is in the same format as is stored 
** in the database without the found length specifier at the start of on-disk
** doclists.
*/
static int fts3TermSelect(
  Fts3Table *p,                   /* Virtual table handle */
  Fts3PhraseToken *pTok,          /* Token to query for */
  int iColumn,                    /* Column to query (or -ve for all columns) */
  const char *zTerm,              /* Term to query for */
  int nTerm,                      /* Size of zTerm in bytes */
  int isPrefix,                   /* True for a prefix search */
  int isReqPos,                   /* True to include position lists in output */
  int *pnOut,                     /* OUT: Size of buffer at *ppOut */
  char **ppOut                    /* OUT: Malloced result buffer */
){
  int i;
  TermSelect tsc;
  Fts3SegFilter filter;           /* Segment term filter configuration */
  Fts3SegReader **apSegment;      /* Array of segments to read data from */
  int nSegment = 0;               /* Size of apSegment array */
  int nAlloc = 16;                /* Allocated size of segment array */
  int rc;                         /* Return code */
  sqlite3_stmt *pStmt = 0;        /* SQL statement to scan %_segdir table */
  int iAge = 0;                   /* Used to assign ages to segments */

  apSegment = (Fts3SegReader **)sqlite3_malloc(sizeof(Fts3SegReader*)*nAlloc);
  if( !apSegment ) return SQLITE_NOMEM;
  rc = sqlite3Fts3SegReaderPending(p, zTerm, nTerm, isPrefix, &apSegment[0]);
  if( rc!=SQLITE_OK ) goto finished;
  if( apSegment[0] ){
    nSegment = 1;
  }

  /* Loop through the entire %_segdir table. For each segment, create a
  ** Fts3SegReader to iterate through the subset of the segment leaves
  ** that may contain a term that matches zTerm/nTerm. For non-prefix
  ** searches, this is always a single leaf. For prefix searches, this
  ** may be a contiguous block of leaves.
  **
  ** The code in this loop does not actually load any leaves into memory
  ** (unless the root node happens to be a leaf). It simply examines the
  ** b-tree structure to determine which leaves need to be inspected.
  */
  rc = sqlite3Fts3AllSegdirs(p, &pStmt);
  while( rc==SQLITE_OK && SQLITE_ROW==(rc = sqlite3_step(pStmt)) ){
    Fts3SegReader *pNew = 0;
  Fts3SegReaderArray *pArray;     /* Seg-reader array for this term */
    int nRoot = sqlite3_column_bytes(pStmt, 4);
    char const *zRoot = sqlite3_column_blob(pStmt, 4);
    if( sqlite3_column_int64(pStmt, 1)==0 ){
      /* The entire segment is stored on the root node (which must be a
      ** leaf). Do not bother inspecting any data in this case, just
      ** create a Fts3SegReader to scan the single leaf. 
      */
      rc = sqlite3Fts3SegReaderNew(p, iAge, 0, 0, 0, zRoot, nRoot, &pNew);
    }else{
      int rc2;                    /* Return value of sqlite3Fts3ReadBlock() */
      sqlite3_int64 i1;           /* Blockid of leaf that may contain zTerm */
      rc = fts3SelectLeaf(p, zTerm, nTerm, zRoot, nRoot, &i1);
      if( rc==SQLITE_OK ){
        sqlite3_int64 i2 = sqlite3_column_int64(pStmt, 2);
        rc = sqlite3Fts3SegReaderNew(p, iAge, i1, i2, 0, 0, 0, &pNew);
      }

  TermSelect tsc;               /* Context object for fts3TermSelectCb() */
      /* The following call to ReadBlock() serves to reset the SQL statement
      ** used to retrieve blocks of data from the %_segments table. If it is
      ** not reset here, then it may remain classified as an active statement 
      ** by SQLite, which may lead to "DROP TABLE" or "DETACH" commands 
      ** failing.
      */ 
      rc2 = sqlite3Fts3ReadBlock(p, 0, 0, 0);
      if( rc==SQLITE_OK ){
        rc = rc2;
      }
    }
    iAge++;

  Fts3SegFilter filter;         /* Segment term filter configuration */
    /* If a new Fts3SegReader was allocated, add it to the apSegment array. */
    assert( pNew!=0 || rc!=SQLITE_OK );
    if( pNew ){
      if( nSegment==nAlloc ){
        Fts3SegReader **pArray;
        nAlloc += 16;
        pArray = (Fts3SegReader **)sqlite3_realloc(
            apSegment, nAlloc*sizeof(Fts3SegReader *)
        );
        if( !pArray ){
          sqlite3Fts3SegReaderFree(p, pNew);
          rc = SQLITE_NOMEM;
          goto finished;
        }

        apSegment = pArray;
      }
      apSegment[nSegment++] = pNew;
    }
  }
  if( rc!=SQLITE_DONE ){
    assert( rc!=SQLITE_OK );
    goto finished;
  }

  pArray = pTok->pArray;
  memset(&tsc, 0, sizeof(TermSelect));
  tsc.isReqPos = isReqPos;

  filter.flags = FTS3_SEGMENT_IGNORE_EMPTY 
        | (isPrefix ? FTS3_SEGMENT_PREFIX : 0)
        | (pTok->isPrefix ? FTS3_SEGMENT_PREFIX : 0)
        | (isReqPos ? FTS3_SEGMENT_REQUIRE_POS : 0)
        | (iColumn<p->nColumn ? FTS3_SEGMENT_COLUMN_FILTER : 0);
  filter.iCol = iColumn;
  filter.zTerm = zTerm;
  filter.nTerm = nTerm;
  filter.zTerm = pTok->z;
  filter.nTerm = pTok->n;

  rc = sqlite3Fts3SegReaderIterate(p, apSegment, nSegment, &filter,
      fts3TermSelectCb, (void *)&tsc
  rc = sqlite3Fts3SegReaderIterate(p, pArray->apSegment, pArray->nSegment, 
      &filter, fts3TermSelectCb, (void *)&tsc
  );
  if( rc==SQLITE_OK ){
    rc = fts3TermSelectMerge(&tsc);
  }

  if( rc==SQLITE_OK ){
    *ppOut = tsc.aaOutput[0];
    *pnOut = tsc.anOutput[0];
  }else{
    int i;
    for(i=0; i<SizeofArray(tsc.aaOutput); i++){
      sqlite3_free(tsc.aaOutput[i]);
    }
  }

  fts3SegReaderArrayFree(pArray);
  pTok->pArray = 0;
  return rc;
}
finished:
  sqlite3_reset(pStmt);
  for(i=0; i<nSegment; i++){
    sqlite3Fts3SegReaderFree(p, apSegment[i]);
  }
  sqlite3_free(apSegment);

/*
** This function counts the total number of docids in the doclist stored
** in buffer aList[], size nList bytes.
**
** If the isPoslist argument is true, then it is assumed that the doclist
** contains a position-list following each docid. Otherwise, it is assumed
** that the doclist is simply a list of docids stored as delta encoded 
** varints.
*/
static int fts3DoclistCountDocids(int isPoslist, char *aList, int nList){
  int nDoc = 0;                   /* Return value */
  if( aList ){
    char *aEnd = &aList[nList];   /* Pointer to one byte after EOF */
    char *p = aList;              /* Cursor */
    if( !isPoslist ){
      /* The number of docids in the list is the same as the number of 
      ** varints. In FTS3 a varint consists of a single byte with the 0x80 
      ** bit cleared and zero or more bytes with the 0x80 bit set. So to
      ** count the varints in the buffer, just count the number of bytes
      ** with the 0x80 bit clear.  */
      while( p<aEnd ) nDoc += (((*p++)&0x80)==0);
    }else{
      while( p<aEnd ){
        nDoc++;
        while( (*p++)&0x80 );     /* Skip docid varint */
        fts3PoslistCopy(0, &p);   /* Skip over position list */
      }
    }
  }

  return nDoc;
}

/*
** Call sqlite3Fts3DeferToken() for each token in the expression pExpr.
*/
static int fts3DeferExpression(Fts3Cursor *pCsr, Fts3Expr *pExpr){
  int rc = SQLITE_OK;
  if( pExpr ){
    rc = fts3DeferExpression(pCsr, pExpr->pLeft);
    if( rc==SQLITE_OK ){
      rc = fts3DeferExpression(pCsr, pExpr->pRight);
    }
    if( pExpr->eType==FTSQUERY_PHRASE ){
      int iCol = pExpr->pPhrase->iColumn;
      int i;
      for(i=0; rc==SQLITE_OK && i<pExpr->pPhrase->nToken; i++){
        Fts3PhraseToken *pToken = &pExpr->pPhrase->aToken[i];
        if( pToken->pDeferred==0 ){
          rc = sqlite3Fts3DeferToken(pCsr, pToken, iCol);
        }
      }
    }
  }
  return rc;
}

/*
** This function removes the position information from a doclist. When
** called, buffer aList (size *pnList bytes) contains a doclist that includes
** position information. This function removes the position information so
** that aList contains only docids, and adjusts *pnList to reflect the new
** (possibly reduced) size of the doclist.
*/
static void fts3DoclistStripPositions(
  char *aList,                    /* IN/OUT: Buffer containing doclist */
  int *pnList                     /* IN/OUT: Size of doclist in bytes */
){
  if( aList ){
    char *aEnd = &aList[*pnList]; /* Pointer to one byte after EOF */
    char *p = aList;              /* Input cursor */
    char *pOut = aList;           /* Output cursor */

  
    while( p<aEnd ){
      sqlite3_int64 delta;
      p += sqlite3Fts3GetVarint(p, &delta);
      fts3PoslistCopy(0, &p);
      pOut += sqlite3Fts3PutVarint(pOut, delta);
    }

    *pnList = (pOut - aList);
  }
}

/* 
** Return a DocList corresponding to the phrase *pPhrase.
**
** If this function returns SQLITE_OK, but *pnOut is set to a negative value,
** then no tokens in the phrase were looked up in the full-text index. This
** is only possible when this function is called from within xFilter(). The
** caller should assume that all documents match the phrase. The actual
** filtering will take place in xNext().
*/
static int fts3PhraseSelect(
  Fts3Table *p,                   /* Virtual table handle */
  Fts3Cursor *pCsr,               /* Virtual table cursor handle */
  Fts3Phrase *pPhrase,            /* Phrase to return a doclist for */
  int isReqPos,                   /* True if output should contain positions */
  char **paOut,                   /* OUT: Pointer to malloc'd result buffer */
  int *pnOut                      /* OUT: Size of buffer at *paOut */
){
  char *pOut = 0;
  int nOut = 0;
  int rc = SQLITE_OK;
  int ii;
  int iCol = pPhrase->iColumn;
  int isTermPos = (pPhrase->nToken>1 || isReqPos);
  Fts3Table *p = (Fts3Table *)pCsr->base.pVtab;
  int isFirst = 1;

  int iPrevTok = 0;
  int nDoc = 0;

  /* If this is an xFilter() evaluation, create a segment-reader for each
  ** phrase token. Or, if this is an xNext() or snippet/offsets/matchinfo
  ** evaluation, only create segment-readers if there are no Fts3DeferredToken
  ** objects attached to the phrase-tokens.
  */
  for(ii=0; ii<pPhrase->nToken; ii++){
    struct PhraseToken *pTok = &pPhrase->aToken[ii];
    char *z = pTok->z;            /* Next token of the phrase */
    int n = pTok->n;              /* Size of z in bytes */
    int isPrefix = pTok->isPrefix;/* True if token is a prefix */
    Fts3PhraseToken *pTok = &pPhrase->aToken[ii];
    if( pTok->pArray==0 ){
      if( (pCsr->eEvalmode==FTS3_EVAL_FILTER)
       || (pCsr->eEvalmode==FTS3_EVAL_NEXT && pCsr->pDeferred==0) 
       || (pCsr->eEvalmode==FTS3_EVAL_MATCHINFO && pTok->bFulltext) 
      ){
        rc = fts3TermSegReaderArray(
            pCsr, pTok->z, pTok->n, pTok->isPrefix, &pTok->pArray
        );
        if( rc!=SQLITE_OK ) return rc;
      }
    }
  }

  for(ii=0; ii<pPhrase->nToken; ii++){
    Fts3PhraseToken *pTok;        /* Token to find doclist for */
    int iTok;                     /* The token being queried this iteration */
    char *pList;                  /* Pointer to token doclist */
    int nList;                    /* Size of buffer at pList */

    /* Select a token to process. If this is an xFilter() call, then tokens 
    ** are processed in order from least to most costly. Otherwise, tokens 
    ** are processed in the order in which they occur in the phrase.
    */
    if( pCsr->eEvalmode==FTS3_EVAL_MATCHINFO ){
      assert( isReqPos );
      iTok = ii;
      pTok = &pPhrase->aToken[iTok];
      if( pTok->bFulltext==0 ) continue;
    }else if( pCsr->eEvalmode==FTS3_EVAL_NEXT || isReqPos ){
      iTok = ii;
      pTok = &pPhrase->aToken[iTok];
    }else{
      int nMinCost = 0x7FFFFFFF;
      int jj;

      /* Find the remaining token with the lowest cost. */
      for(jj=0; jj<pPhrase->nToken; jj++){
        Fts3SegReaderArray *pArray = pPhrase->aToken[jj].pArray;
        if( pArray && pArray->nCost<nMinCost ){
          iTok = jj;
          nMinCost = pArray->nCost;
        }
      }
      pTok = &pPhrase->aToken[iTok];

      /* This branch is taken if it is determined that loading the doclist
      ** for the next token would require more IO than loading all documents
      ** currently identified by doclist pOut/nOut. No further doclists will
      ** be loaded from the full-text index for this phrase.
      */
      if( nMinCost>nDoc && ii>0 ){
        rc = fts3DeferExpression(pCsr, pCsr->pExpr);
        break;
      }
    }

    if( pCsr->eEvalmode==FTS3_EVAL_NEXT && pTok->pDeferred ){
    rc = fts3TermSelect(p, iCol, z, n, isPrefix, isTermPos, &nList, &pList);
      rc = fts3DeferredTermSelect(pTok->pDeferred, isTermPos, &nList, &pList);
    }else{
      assert( pTok->pArray );
      rc = fts3TermSelect(p, pTok, iCol, isTermPos, &nList, &pList);
      pTok->bFulltext = 1;
    }
    assert( rc!=SQLITE_OK || pCsr->eEvalmode || pTok->pArray==0 );
    if( rc!=SQLITE_OK ) break;

    if( ii==0 ){
    if( isFirst ){
      pOut = pList;
      nOut = nList;
      if( pCsr->eEvalmode==FTS3_EVAL_FILTER && pPhrase->nToken>1 ){
        nDoc = fts3DoclistCountDocids(1, pOut, nOut);
      }
      isFirst = 0;
      iPrevTok = iTok;
    }else{
      /* Merge the new term list and the current output. If this is the
      ** last term in the phrase, and positions are not required in the
      ** output of this function, the positions can be dropped as part
      /* Merge the new term list and the current output. */
      char *aLeft, *aRight;
      int nLeft, nRight;
      int nDist;
      int mt;

      /* If this is the final token of the phrase, and positions were not
      ** of this merge. Either way, the result of this merge will be
      ** smaller than nList bytes. The code in fts3DoclistMerge() is written
      ** so that it is safe to use pList as the output as well as an input
      ** in this case.
      ** requested by the caller, use MERGE_PHRASE instead of POS_PHRASE.
      ** This drops the position information from the output list.
      */
      int mergetype = MERGE_POS_PHRASE;
      if( ii==pPhrase->nToken-1 && !isReqPos ){
        mergetype = MERGE_PHRASE;
      mt = MERGE_POS_PHRASE;
      if( ii==pPhrase->nToken-1 && !isReqPos ) mt = MERGE_PHRASE;

      assert( iPrevTok!=iTok );
      if( iPrevTok<iTok ){
        aLeft = pOut;
        nLeft = nOut;
        aRight = pList;
        nRight = nList;
        nDist = iTok-iPrevTok;
        iPrevTok = iTok;
      }else{
        aRight = pOut;
        nRight = nOut;
        aLeft = pList;
        nLeft = nList;
        nDist = iPrevTok-iTok;
      }
      pOut = aRight;
      fts3DoclistMerge(mergetype, 0, 0, pList, &nOut, pOut, nOut, pList, nList);
      sqlite3_free(pOut);
      fts3DoclistMerge(
          mt, nDist, 0, pOut, &nOut, aLeft, nLeft, aRight, nRight, &nDoc
      );
      sqlite3_free(aLeft);
      pOut = pList;
    }
    assert( nOut==0 || pOut!=0 );
  }

  if( rc==SQLITE_OK ){
    if( ii!=pPhrase->nToken ){
      assert( pCsr->eEvalmode==FTS3_EVAL_FILTER && isReqPos==0 );
      fts3DoclistStripPositions(pOut, &nOut);
    }
    *paOut = pOut;
    *pnOut = nOut;
  }else{
    sqlite3_free(pOut);
  }
  return rc;
}

/*
** This function merges two doclists according to the requirements of a
** NEAR operator.
**
** Both input doclists must include position information. The output doclist 
** includes position information if the first argument to this function
** is MERGE_POS_NEAR, or does not if it is MERGE_NEAR.
*/
static int fts3NearMerge(
  int mergetype,                  /* MERGE_POS_NEAR or MERGE_NEAR */
  int nNear,                      /* Parameter to NEAR operator */
  int nTokenLeft,                 /* Number of tokens in LHS phrase arg */
  char *aLeft,                    /* Doclist for LHS (incl. positions) */
  int nLeft,                      /* Size of LHS doclist in bytes */
  int nTokenRight,                /* As nTokenLeft */
  char *aRight,                   /* As aLeft */
  int nRight,                     /* As nRight */
  char **paOut,                   /* OUT: Results of merge (malloced) */
  int *pnOut                      /* OUT: Sized of output buffer */
){
  char *aOut;
  int rc;
  char *aOut;                     /* Buffer to write output doclist to */
  int rc;                         /* Return code */

  assert( mergetype==MERGE_POS_NEAR || MERGE_NEAR );

  aOut = sqlite3_malloc(nLeft+nRight+1);
  if( aOut==0 ){
    rc = SQLITE_NOMEM;
  }else{
    rc = fts3DoclistMerge(mergetype, nNear+nTokenRight, nNear+nTokenLeft, 
      aOut, pnOut, aLeft, nLeft, aRight, nRight
      aOut, pnOut, aLeft, nLeft, aRight, nRight, 0
    );
    if( rc!=SQLITE_OK ){
      sqlite3_free(aOut);
      aOut = 0;
    }
  }

  *paOut = aOut;
  return rc;
}

/*
** This function is used as part of the processing for the snippet() and
** offsets() functions.
**
** Both pLeft and pRight are expression nodes of type FTSQUERY_PHRASE. Both
** have their respective doclists (including position information) loaded
** in Fts3Expr.aDoclist/nDoclist. This function removes all entries from
** each doclist that are not within nNear tokens of a corresponding entry
** in the other doclist.
*/
int sqlite3Fts3ExprNearTrim(Fts3Expr *pLeft, Fts3Expr *pRight, int nNear){
  int rc;
  int rc;                         /* Return code */

  assert( pLeft->eType==FTSQUERY_PHRASE );
  assert( pRight->eType==FTSQUERY_PHRASE );
  assert( pLeft->isLoaded && pRight->isLoaded );

  if( pLeft->aDoclist==0 || pRight->aDoclist==0 ){
    sqlite3_free(pLeft->aDoclist);
    sqlite3_free(pRight->aDoclist);
    pRight->aDoclist = 0;
    pLeft->aDoclist = 0;
    rc = SQLITE_OK;
  }else{
    char *aOut;
    int nOut;
    char *aOut;                   /* Buffer in which to assemble new doclist */
    int nOut;                     /* Size of buffer aOut in bytes */

    rc = fts3NearMerge(MERGE_POS_NEAR, nNear, 
        pLeft->pPhrase->nToken, pLeft->aDoclist, pLeft->nDoclist,
        pRight->pPhrase->nToken, pRight->aDoclist, pRight->nDoclist,
        &aOut, &nOut
    );
    if( rc!=SQLITE_OK ) return rc;

    sqlite3_free(pLeft->aDoclist);
    pLeft->aDoclist = aOut;
    pLeft->nDoclist = nOut;
  }
  return rc;
}


/*
** Allocate an Fts3SegReaderArray for each token in the expression pExpr. 
** The allocated objects are stored in the Fts3PhraseToken.pArray member
** variables of each token structure.
*/
static int fts3ExprAllocateSegReaders(
  Fts3Cursor *pCsr,               /* FTS3 table */
  Fts3Expr *pExpr,                /* Expression to create seg-readers for */
  int *pnExpr                     /* OUT: Number of AND'd expressions */
){
  int rc = SQLITE_OK;             /* Return code */

  assert( pCsr->eEvalmode==FTS3_EVAL_FILTER );
  if( pnExpr && pExpr->eType!=FTSQUERY_AND ){
    (*pnExpr)++;
    pnExpr = 0;
  }

  if( pExpr->eType==FTSQUERY_PHRASE ){
    Fts3Phrase *pPhrase = pExpr->pPhrase;
    int ii;

    for(ii=0; rc==SQLITE_OK && ii<pPhrase->nToken; ii++){
      Fts3PhraseToken *pTok = &pPhrase->aToken[ii];
      if( pTok->pArray==0 ){
        rc = fts3TermSegReaderArray(
            pCsr, pTok->z, pTok->n, pTok->isPrefix, &pTok->pArray
        );
      }
    }
  }else{ 
    rc = fts3ExprAllocateSegReaders(pCsr, pExpr->pLeft, pnExpr);
    if( rc==SQLITE_OK ){
      rc = fts3ExprAllocateSegReaders(pCsr, pExpr->pRight, pnExpr);
    }
  }
  return rc;
}

/*
** Free the Fts3SegReaderArray objects associated with each token in the
** expression pExpr. In other words, this function frees the resources
** allocated by fts3ExprAllocateSegReaders().
*/
static void fts3ExprFreeSegReaders(Fts3Expr *pExpr){
  if( pExpr ){
    Fts3Phrase *pPhrase = pExpr->pPhrase;
    if( pPhrase ){
      int kk;
      for(kk=0; kk<pPhrase->nToken; kk++){
        fts3SegReaderArrayFree(pPhrase->aToken[kk].pArray);
        pPhrase->aToken[kk].pArray = 0;
      }
    }
    fts3ExprFreeSegReaders(pExpr->pLeft);
    fts3ExprFreeSegReaders(pExpr->pRight);
  }
}

/*
** Return the sum of the costs of all tokens in the expression pExpr. This
** function must be called after Fts3SegReaderArrays have been allocated
** for all tokens using fts3ExprAllocateSegReaders().
*/
int fts3ExprCost(Fts3Expr *pExpr){
  int nCost;                      /* Return value */
  if( pExpr->eType==FTSQUERY_PHRASE ){
    Fts3Phrase *pPhrase = pExpr->pPhrase;
    int ii;
    nCost = 0;
    for(ii=0; ii<pPhrase->nToken; ii++){
      nCost += pPhrase->aToken[ii].pArray->nCost;
    }
  }else{
    nCost = fts3ExprCost(pExpr->pLeft) + fts3ExprCost(pExpr->pRight);
  }
  return nCost;
}

/*
** The following is a helper function (and type) for fts3EvalExpr(). It
** must be called after Fts3SegReaders have been allocated for every token
** in the expression. See the context it is called from in fts3EvalExpr()
** for further explanation.
*/
typedef struct ExprAndCost ExprAndCost;
struct ExprAndCost {
  Fts3Expr *pExpr;
  int nCost;
};
static void fts3ExprAssignCosts(
  Fts3Expr *pExpr,                /* Expression to create seg-readers for */
  ExprAndCost **ppExprCost        /* OUT: Write to *ppExprCost */
){
  if( pExpr->eType==FTSQUERY_AND ){
    fts3ExprAssignCosts(pExpr->pLeft, ppExprCost);
    fts3ExprAssignCosts(pExpr->pRight, ppExprCost);
  }else{
    (*ppExprCost)->pExpr = pExpr;
    (*ppExprCost)->nCost = fts3ExprCost(pExpr);;
    (*ppExprCost)++;
  }
}

/*
** Evaluate the full-text expression pExpr against fts3 table pTab. Store
** the resulting doclist in *paOut and *pnOut.  This routine mallocs for
** the space needed to store the output.  The caller is responsible for
** Evaluate the full-text expression pExpr against FTS3 table pTab. Store
** the resulting doclist in *paOut and *pnOut. This routine mallocs for
** the space needed to store the output. The caller is responsible for
** freeing the space when it has finished.
**
** This function is called in two distinct contexts:
**
**   * From within the virtual table xFilter() method. In this case, the
**     output doclist contains entries for all rows in the table, based on
**     data read from the full-text index.
**
**     In this case, if the query expression contains one or more tokens that 
**     are very common, then the returned doclist may contain a superset of 
**     the documents that actually match the expression.
**
**   * From within the virtual table xNext() method. This call is only made
**     if the call from within xFilter() found that there were very common 
**     tokens in the query expression and did return a superset of the 
**     matching documents. In this case the returned doclist contains only
**     entries that correspond to the current row of the table. Instead of
**     reading the data for each token from the full-text index, the data is
**     already available in-memory in the Fts3PhraseToken.pDeferred structures.
**     See fts3EvalDeferred() for how it gets there.
**
** In the first case above, Fts3Cursor.doDeferred==0. In the second (if it is
** required) Fts3Cursor.doDeferred==1.
**
** If the SQLite invokes the snippet(), offsets() or matchinfo() function
** as part of a SELECT on an FTS3 table, this function is called on each
** individual phrase expression in the query. If there were very common tokens
** found in the xFilter() call, then this function is called once for phrase
** for each row visited, and the returned doclist contains entries for the
** current row only. Otherwise, if there were no very common tokens, then this
** function is called once only for each phrase in the query and the returned
** doclist contains entries for all rows of the table.
**
** Fts3Cursor.doDeferred==1 when this function is called on phrases as a
** result of a snippet(), offsets() or matchinfo() invocation.
*/
static int evalFts3Expr(
  Fts3Table *p,                   /* Virtual table handle */
static int fts3EvalExpr(
  Fts3Cursor *p,                  /* Virtual table cursor handle */
  Fts3Expr *pExpr,                /* Parsed fts3 expression */
  char **paOut,                   /* OUT: Pointer to malloc'd result buffer */
  int *pnOut,                     /* OUT: Size of buffer at *paOut */
  int isReqPos                    /* Require positions in output buffer */
){
  int rc = SQLITE_OK;             /* Return code */

  /* Zero the output parameters. */
  *paOut = 0;
  *pnOut = 0;

  if( pExpr ){
    assert( pExpr->eType==FTSQUERY_PHRASE 
         || pExpr->eType==FTSQUERY_NEAR 
         || isReqPos==0
    assert( pExpr->eType==FTSQUERY_NEAR   || pExpr->eType==FTSQUERY_OR     
         || pExpr->eType==FTSQUERY_AND    || pExpr->eType==FTSQUERY_NOT
         || pExpr->eType==FTSQUERY_PHRASE
    );
    assert( pExpr->eType==FTSQUERY_PHRASE || isReqPos==0 );

    if( pExpr->eType==FTSQUERY_PHRASE ){
      rc = fts3PhraseSelect(p, pExpr->pPhrase, 
      rc = fts3PhraseSelect(p, pExpr->pPhrase,
          isReqPos || (pExpr->pParent && pExpr->pParent->eType==FTSQUERY_NEAR),
          paOut, pnOut
      );
      fts3ExprFreeSegReaders(pExpr);
    }else if( p->eEvalmode==FTS3_EVAL_FILTER && pExpr->eType==FTSQUERY_AND ){
      ExprAndCost *aExpr = 0;     /* Array of AND'd expressions and costs */
      int nExpr = 0;              /* Size of aExpr[] */
      char *aRet = 0;             /* Doclist to return to caller */
      int nRet = 0;               /* Length of aRet[] in bytes */
      int nDoc = 0x7FFFFFFF;

      assert( !isReqPos );

      rc = fts3ExprAllocateSegReaders(p, pExpr, &nExpr);
      if( rc==SQLITE_OK ){
        assert( nExpr>1 );
        aExpr = sqlite3_malloc(sizeof(ExprAndCost) * nExpr);
        if( !aExpr ) rc = SQLITE_NOMEM;
      }
      if( rc==SQLITE_OK ){
        int ii;                   /* Used to iterate through expressions */

        fts3ExprAssignCosts(pExpr, &aExpr);
        aExpr -= nExpr;
        for(ii=0; ii<nExpr; ii++){
          char *aNew;
          int nNew;
          int jj;
          ExprAndCost *pBest = 0;
  
          for(jj=0; jj<nExpr; jj++){
            ExprAndCost *pCand = &aExpr[jj];
            if( pCand->pExpr && (pBest==0 || pCand->nCost<pBest->nCost) ){
              pBest = pCand;
            }
          }
  
          if( pBest->nCost>nDoc ){
            rc = fts3DeferExpression(p, p->pExpr);
            break;
          }else{
            rc = fts3EvalExpr(p, pBest->pExpr, &aNew, &nNew, 0);
            if( rc!=SQLITE_OK ) break;
            pBest->pExpr = 0;
            if( ii==0 ){
              aRet = aNew;
              nRet = nNew;
              nDoc = fts3DoclistCountDocids(0, aRet, nRet);
            }else{
              fts3DoclistMerge(
                  MERGE_AND, 0, 0, aRet, &nRet, aRet, nRet, aNew, nNew, &nDoc
              );
              sqlite3_free(aNew);
            }
          }
        }
      }

      *paOut = aRet;
      *pnOut = nRet;
      sqlite3_free(aExpr);
      fts3ExprFreeSegReaders(pExpr);

    }else{
      char *aLeft;
      char *aRight;
      int nLeft;
      int nRight;

      if( 0==(rc = evalFts3Expr(p, pExpr->pRight, &aRight, &nRight, isReqPos))
       && 0==(rc = evalFts3Expr(p, pExpr->pLeft, &aLeft, &nLeft, isReqPos))
      ){
        assert( pExpr->eType==FTSQUERY_NEAR || pExpr->eType==FTSQUERY_OR     
            || pExpr->eType==FTSQUERY_AND  || pExpr->eType==FTSQUERY_NOT
        );
      assert( pExpr->eType==FTSQUERY_NEAR 
           || pExpr->eType==FTSQUERY_OR
           || pExpr->eType==FTSQUERY_NOT
           || (pExpr->eType==FTSQUERY_AND && p->eEvalmode==FTS3_EVAL_NEXT)
      );

      if( 0==(rc = fts3EvalExpr(p, pExpr->pRight, &aRight, &nRight, isReqPos))
       && 0==(rc = fts3EvalExpr(p, pExpr->pLeft, &aLeft, &nLeft, isReqPos))
      ){
        switch( pExpr->eType ){
          case FTSQUERY_NEAR: {
            Fts3Expr *pLeft;
            Fts3Expr *pRight;
            int mergetype = isReqPos ? MERGE_POS_NEAR : MERGE_NEAR;
            int mergetype = MERGE_NEAR;
           
            if( pExpr->pParent && pExpr->pParent->eType==FTSQUERY_NEAR ){
              mergetype = MERGE_POS_NEAR;
            }
            pLeft = pExpr->pLeft;
            while( pLeft->eType==FTSQUERY_NEAR ){ 
              pLeft=pLeft->pRight;
            }

            /* Allocate a buffer for the output. The maximum size is the
            ** sum of the sizes of the two input buffers. The +1 term is
            ** so that a buffer of zero bytes is never allocated - this can
            ** cause fts3DoclistMerge() to incorrectly return SQLITE_NOMEM.
            */
            char *aBuffer = sqlite3_malloc(nRight+nLeft+1);
            rc = fts3DoclistMerge(MERGE_OR, 0, 0, aBuffer, pnOut,
                aLeft, nLeft, aRight, nRight
                aLeft, nLeft, aRight, nRight, 0
            );
            *paOut = aBuffer;
            sqlite3_free(aLeft);
            break;
          }

          default: {
            assert( FTSQUERY_NOT==MERGE_NOT && FTSQUERY_AND==MERGE_AND );
            fts3DoclistMerge(pExpr->eType, 0, 0, aLeft, pnOut,
                aLeft, nLeft, aRight, nRight
                aLeft, nLeft, aRight, nRight, 0
            );
            *paOut = aLeft;
            break;
          }
        }
      }
      sqlite3_free(aRight);
    }
  }

  return rc;
}

/*
** This function is called from within xNext() for each row visited by
** an FTS3 query. If evaluating the FTS3 query expression within xFilter()
** was able to determine the exact set of matching rows, this function sets
** *pbRes to true and returns SQLITE_IO immediately.
**
** Otherwise, if evaluating the query expression within xFilter() returned a
** superset of the matching documents instead of an exact set (this happens
** when the query includes very common tokens and it is deemed too expensive to
** load their doclists from disk), this function tests if the current row
** really does match the FTS3 query.
**
** If an error occurs, an SQLite error code is returned. Otherwise, SQLITE_OK
** is returned and *pbRes is set to true if the current row matches the
** FTS3 query (and should be included in the results returned to SQLite), or
** false otherwise.
*/
static int fts3EvalDeferred(
  Fts3Cursor *pCsr,               /* FTS3 cursor pointing at row to test */
  int *pbRes                      /* OUT: Set to true if row is a match */
){
  int rc = SQLITE_OK;
  if( pCsr->pDeferred==0 ){
    *pbRes = 1;
  }else{
    rc = fts3CursorSeek(0, pCsr);
    if( rc==SQLITE_OK ){
      sqlite3Fts3FreeDeferredDoclists(pCsr);
      rc = sqlite3Fts3CacheDeferredDoclists(pCsr);
    }
    if( rc==SQLITE_OK ){
      char *a = 0;
      int n = 0;
      rc = fts3EvalExpr(pCsr, pCsr->pExpr, &a, &n, 0);
      assert( n>=0 );
      *pbRes = (n>0);
      sqlite3_free(a);
    }
  }
  return rc;
}

/*
** Advance the cursor to the next row in the %_content table that
** matches the search criteria.  For a MATCH search, this will be
** the next row that matches. For a full-table scan, this will be
** simply the next row in the %_content table.  For a docid lookup,
** this routine simply sets the EOF flag.
**
** Return SQLITE_OK if nothing goes wrong.  SQLITE_OK is returned
** even if we reach end-of-file.  The fts3EofMethod() will be called
** subsequently to determine whether or not an EOF was hit.
*/
static int fts3NextMethod(sqlite3_vtab_cursor *pCursor){
  int res;
  int rc = SQLITE_OK;             /* Return code */
  Fts3Cursor *pCsr = (Fts3Cursor *)pCursor;

  pCsr->eEvalmode = FTS3_EVAL_NEXT;
  do {
    if( pCsr->aDoclist==0 ){
      if( SQLITE_ROW!=sqlite3_step(pCsr->pStmt) ){
        pCsr->isEof = 1;
        rc = sqlite3_reset(pCsr->pStmt);
        break;
      }
      pCsr->iPrevId = sqlite3_column_int64(pCsr->pStmt, 0);
    }else{
      if( pCsr->pNextId>=&pCsr->aDoclist[pCsr->nDoclist] ){
        pCsr->isEof = 1;
        break;
      }
      sqlite3_reset(pCsr->pStmt);
      fts3GetDeltaVarint(&pCsr->pNextId, &pCsr->iPrevId);
      pCsr->isRequireSeek = 1;
      pCsr->isMatchinfoNeeded = 1;
    }
  }while( SQLITE_OK==(rc = fts3EvalDeferred(pCsr, &res)) && res==0 );

  return rc;
}

/*
** This is the xFilter interface for the virtual table.  See
** the virtual table xFilter method documentation for additional
** information.
**
** If idxNum==FTS3_FULLSCAN_SEARCH then do a full table scan against
** the %_content table.
**
** If idxNum==FTS3_DOCID_SEARCH then do a docid lookup for a single entry
** in the %_content table.
**
** If idxNum>=FTS3_FULLTEXT_SEARCH then use the full text index.  The
** column on the left-hand side of the MATCH operator is column
** number idxNum-FTS3_FULLTEXT_SEARCH, 0 indexed.  argv[0] is the right-hand
** side of the MATCH operator.
*/
/* TODO(shess) Upgrade the cursor initialization and destruction to
** account for fts3FilterMethod() being called multiple times on the
** same cursor. The current solution is very fragile. Apply fix to
** fts3 as appropriate.
*/
static int fts3FilterMethod(
  sqlite3_vtab_cursor *pCursor,   /* The cursor used for this query */
  int idxNum,                     /* Strategy index */
  const char *idxStr,             /* Unused */
  int nVal,                       /* Number of elements in apVal */
  sqlite3_value **apVal           /* Arguments for the indexing scheme */
){

  UNUSED_PARAMETER(idxStr);
  UNUSED_PARAMETER(nVal);

  assert( idxNum>=0 && idxNum<=(FTS3_FULLTEXT_SEARCH+p->nColumn) );
  assert( nVal==0 || nVal==1 );
  assert( (nVal==0)==(idxNum==FTS3_FULLSCAN_SEARCH) );
  assert( p->pSegments==0 );

  /* In case the cursor has been used before, clear it now. */
  sqlite3_finalize(pCsr->pStmt);
  sqlite3_free(pCsr->aDoclist);
  sqlite3Fts3ExprFree(pCsr->pExpr);
  memset(&pCursor[1], 0, sizeof(Fts3Cursor)-sizeof(sqlite3_vtab_cursor));

  /* Compile a SELECT statement for this cursor. For a full-table-scan, the
  ** statement loops through all rows of the %_content table. For a
  ** full-text query or docid lookup, the statement retrieves a single
  ** row by docid.
  */
  zSql = sqlite3_mprintf(azSql[idxNum==FTS3_FULLSCAN_SEARCH], p->zDb, p->zName);
  if( !zSql ){
    rc = SQLITE_NOMEM;
  }else{
    rc = sqlite3_prepare_v2(p->db, zSql, -1, &pCsr->pStmt, 0);
    sqlite3_free(zSql);
  }
  if( rc!=SQLITE_OK ) return rc;
  pCsr->eSearch = (i16)idxNum;

  if( idxNum==FTS3_DOCID_SEARCH ){
  if( idxNum!=FTS3_DOCID_SEARCH && idxNum!=FTS3_FULLSCAN_SEARCH ){
    rc = sqlite3_bind_value(pCsr->pStmt, 1, apVal[0]);
  }else if( idxNum!=FTS3_FULLSCAN_SEARCH ){
    int iCol = idxNum-FTS3_FULLTEXT_SEARCH;
    const char *zQuery = (const char *)sqlite3_value_text(apVal[0]);

    if( zQuery==0 && sqlite3_value_type(apVal[0])!=SQLITE_NULL ){
      return SQLITE_NOMEM;
    }

      }
      return rc;
    }

    rc = sqlite3Fts3ReadLock(p);
    if( rc!=SQLITE_OK ) return rc;

    rc = evalFts3Expr(p, pCsr->pExpr, &pCsr->aDoclist, &pCsr->nDoclist, 0);
    rc = fts3EvalExpr(pCsr, pCsr->pExpr, &pCsr->aDoclist, &pCsr->nDoclist, 0);
    sqlite3Fts3SegmentsClose(p);
    if( rc!=SQLITE_OK ) return rc;
    pCsr->pNextId = pCsr->aDoclist;
    pCsr->iPrevId = 0;
  }

  /* Compile a SELECT statement for this cursor. For a full-table-scan, the
  ** statement loops through all rows of the %_content table. For a
  ** full-text query or docid lookup, the statement retrieves a single
  ** row by docid.
  */
  zSql = sqlite3_mprintf(azSql[idxNum==FTS3_FULLSCAN_SEARCH], p->zDb, p->zName);
  if( !zSql ){
    rc = SQLITE_NOMEM;
  }else{
    rc = sqlite3_prepare_v2(p->db, zSql, -1, &pCsr->pStmt, 0);
    sqlite3_free(zSql);
  }
  if( rc==SQLITE_OK && idxNum==FTS3_DOCID_SEARCH ){
    rc = sqlite3_bind_value(pCsr->pStmt, 1, apVal[0]);
  }
  pCsr->eSearch = (i16)idxNum;

  if( rc!=SQLITE_OK ) return rc;
  return fts3NextMethod(pCursor);
}

/* 
** This is the xEof method of the virtual table. SQLite calls this 

** rowid should be written to *pRowid.
*/
static int fts3RowidMethod(sqlite3_vtab_cursor *pCursor, sqlite_int64 *pRowid){
  Fts3Cursor *pCsr = (Fts3Cursor *) pCursor;
  if( pCsr->aDoclist ){
    *pRowid = pCsr->iPrevId;
  }else{
    /* This branch runs if the query is implemented using a full-table scan
    ** (not using the full-text index). In this case grab the rowid from the
    ** SELECT statement.
    */
    assert( pCsr->isRequireSeek==0 );
    *pRowid = sqlite3_column_int64(pCsr->pStmt, 0);
  }
  return SQLITE_OK;
}

/* 
** This is the xColumn method, called by SQLite to request a value from

}

/*
** Implementation of xSync() method. Flush the contents of the pending-terms
** hash-table to the database.
*/
static int fts3SyncMethod(sqlite3_vtab *pVtab){
  return sqlite3Fts3PendingTermsFlush((Fts3Table *)pVtab);
  int rc = sqlite3Fts3PendingTermsFlush((Fts3Table *)pVtab);
  sqlite3Fts3SegmentsClose((Fts3Table *)pVtab);
  return rc;
}

/*
** Implementation of xBegin() method. This is a no-op.
*/
static int fts3BeginMethod(sqlite3_vtab *pVtab){
  UNUSED_PARAMETER(pVtab);

/*
** Load the doclist associated with expression pExpr to pExpr->aDoclist.
** The loaded doclist contains positions as well as the document ids.
** This is used by the matchinfo(), snippet() and offsets() auxillary
** functions.
*/
int sqlite3Fts3ExprLoadDoclist(Fts3Table *pTab, Fts3Expr *pExpr){
  return evalFts3Expr(pTab, pExpr, &pExpr->aDoclist, &pExpr->nDoclist, 1);
int sqlite3Fts3ExprLoadDoclist(Fts3Cursor *pCsr, Fts3Expr *pExpr){
  int rc;
  assert( pExpr->eType==FTSQUERY_PHRASE && pExpr->pPhrase );
  assert( pCsr->eEvalmode==FTS3_EVAL_NEXT );
  rc = fts3EvalExpr(pCsr, pExpr, &pExpr->aDoclist, &pExpr->nDoclist, 1);
  return rc;
}

int sqlite3Fts3ExprLoadFtDoclist(
  Fts3Cursor *pCsr, 
  Fts3Expr *pExpr,
  char **paDoclist,
  int *pnDoclist
){
  int rc;
  assert( pCsr->eEvalmode==FTS3_EVAL_NEXT );
  assert( pExpr->eType==FTSQUERY_PHRASE && pExpr->pPhrase );
  pCsr->eEvalmode = FTS3_EVAL_MATCHINFO;
  rc = fts3EvalExpr(pCsr, pExpr, paDoclist, pnDoclist, 1);
  pCsr->eEvalmode = FTS3_EVAL_NEXT;
  return rc;
}

/*
** After ExprLoadDoclist() (see above) has been called, this function is
** used to iterate/search through the position lists that make up the doclist
** stored in pExpr->aDoclist.
*/

** message is written to context pContext and SQLITE_ERROR returned. The
** string passed via zFunc is used as part of the error message.
*/
static int fts3FunctionArg(
  sqlite3_context *pContext,      /* SQL function call context */
  const char *zFunc,              /* Function name */
  sqlite3_value *pVal,            /* argv[0] passed to function */
  Fts3Cursor **ppCsr         /* OUT: Store cursor handle here */
  Fts3Cursor **ppCsr              /* OUT: Store cursor handle here */
){
  Fts3Cursor *pRet;
  if( sqlite3_value_type(pVal)!=SQLITE_BLOB 
   || sqlite3_value_bytes(pVal)!=sizeof(Fts3Cursor *)
  ){
    char *zErr = sqlite3_mprintf("illegal first argument to %s", zFunc);
    sqlite3_result_error(pContext, zErr, -1);

*/
static void fts3MatchinfoFunc(
  sqlite3_context *pContext,      /* SQLite function call context */
  int nVal,                       /* Size of argument array */
  sqlite3_value **apVal           /* Array of arguments */
){
  Fts3Cursor *pCsr;               /* Cursor handle passed through apVal[0] */

  if( nVal!=1 ){
  assert( nVal==1 );
    sqlite3_result_error(pContext,
        "wrong number of arguments to function matchinfo()", -1);
    return;
  }

  if( SQLITE_OK==fts3FunctionArg(pContext, "matchinfo", apVal[0], &pCsr) ){
    sqlite3Fts3Matchinfo(pContext, pCsr);
  }
}

/*
** This routine implements the xFindFunction method for the FTS3

    return rc;
  }

  fts3DbExec(&rc, db,
    "ALTER TABLE %Q.'%q_content'  RENAME TO '%q_content';",
    p->zDb, p->zName, zName
  );
  if( rc==SQLITE_ERROR ) rc = SQLITE_OK;
  if( p->bHasDocsize ){
    fts3DbExec(&rc, db,
      "ALTER TABLE %Q.'%q_docsize'  RENAME TO '%q_docsize';",
      p->zDb, p->zName, zName
    );
    fts3DbExec(&rc, db,
      "ALTER TABLE %Q.'%q_stat'  RENAME TO '%q_stat';",

  /* iVersion      */ 0,
  /* xCreate       */ fts3CreateMethod,
  /* xConnect      */ fts3ConnectMethod,
  /* xBestIndex    */ fts3BestIndexMethod,
  /* xDisconnect   */ fts3DisconnectMethod,
  /* xDestroy      */ fts3DestroyMethod,
  /* xOpen         */ fts3OpenMethod,
  /* xClose        */ fulltextClose,
  /* xClose        */ fts3CloseMethod,
  /* xFilter       */ fts3FilterMethod,
  /* xNext         */ fts3NextMethod,
  /* xEof          */ fts3EofMethod,
  /* xColumn       */ fts3ColumnMethod,
  /* xRowid        */ fts3RowidMethod,
  /* xUpdate       */ fts3UpdateMethod,
  /* xBegin        */ fts3BeginMethod,

static void hashDestroy(void *p){
  Fts3Hash *pHash = (Fts3Hash *)p;
  sqlite3Fts3HashClear(pHash);
  sqlite3_free(pHash);
}

/*
** The fts3 built-in tokenizers - "simple" and "porter" - are implemented
** in files fts3_tokenizer1.c and fts3_porter.c respectively. The following
** two forward declarations are for functions declared in these files
** used to retrieve the respective implementations.
** The fts3 built-in tokenizers - "simple", "porter" and "icu"- are 
** implemented in files fts3_tokenizer1.c, fts3_porter.c and fts3_icu.c
** respectively. The following three forward declarations are for functions
** declared in these files used to retrieve the respective implementations.
**
** Calling sqlite3Fts3SimpleTokenizerModule() sets the value pointed
** to by the argument to point to the "simple" tokenizer implementation.
** Function ...PorterTokenizerModule() sets *pModule to point to the
** porter tokenizer/stemmer implementation.
** And so on.
*/
void sqlite3Fts3SimpleTokenizerModule(sqlite3_tokenizer_module const**ppModule);
void sqlite3Fts3PorterTokenizerModule(sqlite3_tokenizer_module const**ppModule);
#ifdef SQLITE_ENABLE_ICU
void sqlite3Fts3IcuTokenizerModule(sqlite3_tokenizer_module const**ppModule);
#endif

/*
** Initialise the fts3 extension. If this extension is built as part
** of the sqlite library, then this function is called directly by
** SQLite. If fts3 is built as a dynamically loadable extension, this
** function is called by the sqlite3_extension_init() entry point.
*/

  ** the two scalar functions. If this is successful, register the
  ** module with sqlite.
  */
  if( SQLITE_OK==rc 
   && SQLITE_OK==(rc = sqlite3Fts3InitHashTable(db, pHash, "fts3_tokenizer"))
   && SQLITE_OK==(rc = sqlite3_overload_function(db, "snippet", -1))
   && SQLITE_OK==(rc = sqlite3_overload_function(db, "offsets", 1))
   && SQLITE_OK==(rc = sqlite3_overload_function(db, "matchinfo", -1))
   && SQLITE_OK==(rc = sqlite3_overload_function(db, "matchinfo", 1))
   && SQLITE_OK==(rc = sqlite3_overload_function(db, "optimize", 1))
  ){
    rc = sqlite3_create_module_v2(
        db, "fts3", &fts3Module, (void *)pHash, hashDestroy
    );
    if( rc==SQLITE_OK ){
      rc = sqlite3_create_module_v2(

** amalgamation.
*/
#ifndef SQLITE_AMALGAMATION
/*
** Macros indicating that conditional expressions are always true or
** false.
*/
#ifdef SQLITE_COVERAGE_TEST
# define ALWAYS(x) (1)
# define NEVER(X)  (0)
#else
# define ALWAYS(x) (x)
# define NEVER(X)  (x)
#endif

/*
** Internal types used by SQLite.
*/
typedef unsigned char u8;         /* 1-byte (or larger) unsigned integer */
typedef short int i16;            /* 2-byte (or larger) signed integer */
typedef unsigned int u32;         /* 4-byte unsigned integer */
typedef sqlite3_uint64 u64;       /* 8-byte unsigned integer */
/*
** Macro used to suppress compiler warnings for unused parameters.
*/
#define UNUSED_PARAMETER(x) (void)(x)
#endif

typedef struct Fts3Table Fts3Table;
typedef struct Fts3Cursor Fts3Cursor;
typedef struct Fts3Expr Fts3Expr;
typedef struct Fts3Phrase Fts3Phrase;
typedef struct Fts3PhraseToken Fts3PhraseToken;

typedef struct Fts3SegFilter Fts3SegFilter;
typedef struct Fts3DeferredToken Fts3DeferredToken;
typedef struct Fts3SegReader Fts3SegReader;
typedef struct Fts3SegFilter Fts3SegFilter;
typedef struct Fts3SegReaderArray Fts3SegReaderArray;

/*
** A connection to a fulltext index is an instance of the following
** structure. The xCreate and xConnect methods create an instance
** of this structure and xDestroy and xDisconnect free that instance.
** All other methods receive a pointer to the structure as one of their
** arguments.
*/
struct Fts3Table {
  sqlite3_vtab base;              /* Base class used by SQLite core */
  sqlite3 *db;                    /* The database connection */
  const char *zDb;                /* logical database name */
  const char *zName;              /* virtual table name */
  int nColumn;                    /* number of named columns in virtual table */
  char **azColumn;                /* column names.  malloced */
  sqlite3_tokenizer *pTokenizer;  /* tokenizer for inserts and queries */

  /* Precompiled statements used by the implementation. Each of these 
  ** statements is run and reset within a single virtual table API call. 
  */
  sqlite3_stmt *aStmt[25];
  sqlite3_stmt *aStmt[24];

  /* Pointer to string containing the SQL:
  **
  ** "SELECT block FROM %_segments WHERE blockid BETWEEN ? AND ? 
  **    ORDER BY blockid"
  */
  char *zSelectLeaves;
  int nLeavesStmt;                /* Valid statements in aLeavesStmt */
  int nLeavesTotal;               /* Total number of prepared leaves stmts */
  int nLeavesAlloc;               /* Allocated size of aLeavesStmt */
  sqlite3_stmt **aLeavesStmt;     /* Array of prepared zSelectLeaves stmts */

  int nNodeSize;                  /* Soft limit for node size */
  u8 bHasContent;                 /* True if %_content table exists */
  u8 bHasDocsize;                 /* True if %_docsize table exists */
  int nPgsz;                      /* Page size for host database */
  char *zSegmentsTbl;             /* Name of %_segments table */
  sqlite3_blob *pSegments;        /* Blob handle open on %_segments table */

  /* The following hash table is used to buffer pending index updates during
  ** transactions. Variable nPendingData estimates the memory size of the 
  ** pending data, including hash table overhead, but not malloc overhead. 
  ** When nPendingData exceeds nMaxPendingData, the buffer is flushed 
  ** automatically. Variable iPrevDocid is the docid of the most recently
  ** inserted record.

struct Fts3Cursor {
  sqlite3_vtab_cursor base;       /* Base class used by SQLite core */
  i16 eSearch;                    /* Search strategy (see below) */
  u8 isEof;                       /* True if at End Of Results */
  u8 isRequireSeek;               /* True if must seek pStmt to %_content row */
  sqlite3_stmt *pStmt;            /* Prepared statement in use by the cursor */
  Fts3Expr *pExpr;                /* Parsed MATCH query string */
  Fts3DeferredToken *pDeferred;   /* Deferred search tokens, if any */
  sqlite3_int64 iPrevId;          /* Previous id read from aDoclist */
  char *pNextId;                  /* Pointer into the body of aDoclist */
  char *aDoclist;                 /* List of docids for full-text queries */
  int nDoclist;                   /* Size of buffer at aDoclist */
  int isMatchinfoNeeded;          /* True when aMatchinfo[] needs filling in */
  u32 *aMatchinfo;                /* Information about most recent match */
  int eEvalmode;                  /* An FTS3_EVAL_XX constant */
  int nRowAvg;                    /* Average size of database rows, in pages */
};

#define FTS3_EVAL_FILTER    0
#define FTS3_EVAL_NEXT      1
#define FTS3_EVAL_MATCHINFO 2

/*
** The Fts3Cursor.eSearch member is always set to one of the following.
** Actualy, Fts3Cursor.eSearch can be greater than or equal to
** FTS3_FULLTEXT_SEARCH.  If so, then Fts3Cursor.eSearch - 2 is the index
** of the column to be searched.  For example, in
**

#define FTS3_FULLSCAN_SEARCH 0    /* Linear scan of %_content table */
#define FTS3_DOCID_SEARCH    1    /* Lookup by rowid on %_content table */
#define FTS3_FULLTEXT_SEARCH 2    /* Full-text index search */

/*
** A "phrase" is a sequence of one or more tokens that must match in
** sequence.  A single token is the base case and the most common case.
** For a sequence of tokens contained in "...", nToken will be the number
** of tokens in the string.
** For a sequence of tokens contained in double-quotes (i.e. "one two three")
** nToken will be the number of tokens in the string.
**
** The nDocMatch and nMatch variables contain data that may be used by the
** matchinfo() function. They are populated when the full-text index is 
** queried for hits on the phrase. If one or more tokens in the phrase
** are deferred, the nDocMatch and nMatch variables are populated based
** on the assumption that the 
*/
struct Fts3PhraseToken {
  char *z;                        /* Text of the token */
  int n;                          /* Number of bytes in buffer z */
  int isPrefix;                   /* True if token ends with a "*" character */
  int bFulltext;                  /* True if full-text index was used */
  Fts3SegReaderArray *pArray;     /* Segment-reader for this token */
  Fts3DeferredToken *pDeferred;   /* Deferred token object for this token */
};

struct Fts3Phrase {
  /* Variables populated by fts3_expr.c when parsing a MATCH expression */
  int nToken;                /* Number of tokens in the phrase */
  int iColumn;               /* Index of column this phrase must match */
  int isNot;                 /* Phrase prefixed by unary not (-) operator */
  struct PhraseToken {
    char *z;                 /* Text of the token */
    int n;                   /* Number of bytes in buffer pointed to by z */
    int isPrefix;            /* True if token ends in with a "*" character */
  } aToken[1];               /* One entry for each token in the phrase */
  Fts3PhraseToken aToken[1]; /* One entry for each token in the phrase */
};

/*
** A tree of these objects forms the RHS of a MATCH operator.
**
** If Fts3Expr.eType is either FTSQUERY_NEAR or FTSQUERY_PHRASE and isLoaded
** is true, then aDoclist points to a malloced buffer, size nDoclist bytes, 

#define FTSQUERY_NEAR   1
#define FTSQUERY_NOT    2
#define FTSQUERY_AND    3
#define FTSQUERY_OR     4
#define FTSQUERY_PHRASE 5


/* fts3_init.c */
int sqlite3Fts3DeleteVtab(int, sqlite3_vtab *);
int sqlite3Fts3InitVtab(int, sqlite3*, void*, int, const char*const*, 
                        sqlite3_vtab **, char **);

/* fts3_write.c */
int sqlite3Fts3UpdateMethod(sqlite3_vtab*,int,sqlite3_value**,sqlite3_int64*);
int sqlite3Fts3PendingTermsFlush(Fts3Table *);
void sqlite3Fts3PendingTermsClear(Fts3Table *);
int sqlite3Fts3Optimize(Fts3Table *);
int sqlite3Fts3SegReaderNew(Fts3Table *,int, sqlite3_int64,
  sqlite3_int64, sqlite3_int64, const char *, int, Fts3SegReader**);
int sqlite3Fts3SegReaderPending(Fts3Table*,const char*,int,int,Fts3SegReader**);
void sqlite3Fts3SegReaderFree(Fts3Table *, Fts3SegReader *);
int sqlite3Fts3SegReaderIterate(
  Fts3Table *, Fts3SegReader **, int, Fts3SegFilter *,
  int (*)(Fts3Table *, void *, char *, int, char *, int),  void *
);
int sqlite3Fts3ReadBlock(Fts3Table*, sqlite3_int64, char const**, int*);
int sqlite3Fts3SegReaderCost(Fts3Cursor *, Fts3SegReader *, int *);
int sqlite3Fts3AllSegdirs(Fts3Table*, sqlite3_stmt **);
int sqlite3Fts3MatchinfoDocsizeLocal(Fts3Cursor*, u32*);
int sqlite3Fts3MatchinfoDocsizeGlobal(Fts3Cursor*, u32*);
int sqlite3Fts3ReadLock(Fts3Table *);
int sqlite3Fts3ReadBlock(Fts3Table*, sqlite3_int64, char **, int*);

void sqlite3Fts3FreeDeferredTokens(Fts3Cursor *);
int sqlite3Fts3DeferToken(Fts3Cursor *, Fts3PhraseToken *, int);
int sqlite3Fts3CacheDeferredDoclists(Fts3Cursor *);
void sqlite3Fts3FreeDeferredDoclists(Fts3Cursor *);
char *sqlite3Fts3DeferredDoclist(Fts3DeferredToken *, int *);

void sqlite3Fts3SegmentsClose(Fts3Table *);

/* Flags allowed as part of the 4th argument to SegmentReaderIterate() */
#define FTS3_SEGMENT_REQUIRE_POS   0x00000001
#define FTS3_SEGMENT_IGNORE_EMPTY  0x00000002
#define FTS3_SEGMENT_COLUMN_FILTER 0x00000004
#define FTS3_SEGMENT_PREFIX        0x00000008

int sqlite3Fts3PutVarint(char *, sqlite3_int64);
int sqlite3Fts3GetVarint(const char *, sqlite_int64 *);
int sqlite3Fts3GetVarint32(const char *, int *);
int sqlite3Fts3VarintLen(sqlite3_uint64);
void sqlite3Fts3Dequote(char *);

char *sqlite3Fts3FindPositions(Fts3Expr *, sqlite3_int64, int);
int sqlite3Fts3ExprLoadDoclist(Fts3Table *, Fts3Expr *);
int sqlite3Fts3ExprLoadDoclist(Fts3Cursor *, Fts3Expr *);
int sqlite3Fts3ExprLoadFtDoclist(Fts3Cursor *, Fts3Expr *, char **, int *);
int sqlite3Fts3ExprNearTrim(Fts3Expr *, Fts3Expr *, int);

/* fts3_tokenizer.c */
const char *sqlite3Fts3NextToken(const char *, int *);
int sqlite3Fts3InitHashTable(sqlite3 *, Fts3Hash *, const char *);
int sqlite3Fts3InitTokenizer(Fts3Hash *pHash, 
  const char *, sqlite3_tokenizer **, const char **, char **

** is defined to accept an argument of type char, and always returns 0 for
** any values that fall outside of the range of the unsigned char type (i.e.
** negative values).
*/
static int fts3isspace(char c){
  return c==' ' || c=='\t' || c=='\n' || c=='\r' || c=='\v' || c=='\f';
}

/*
** Allocate nByte bytes of memory using sqlite3_malloc(). If successful,
** zero the memory before returning a pointer to it. If unsuccessful, 
** return NULL.
*/
static void *fts3MallocZero(int nByte){
  void *pRet = sqlite3_malloc(nByte);
  if( pRet ) memset(pRet, 0, nByte);
  return pRet;
}


/*
** Extract the next token from buffer z (length n) using the tokenizer
** and other information (column names etc.) in pParse. Create an Fts3Expr
** structure of type FTSQUERY_PHRASE containing a phrase consisting of this
** single token and set *ppExpr to point to it. If the end of the buffer is
** reached before a token is found, set *ppExpr to zero. It is the

    int nByte;                               /* total space to allocate */

    pCursor->pTokenizer = pTokenizer;
    rc = pModule->xNext(pCursor, &zToken, &nToken, &iStart, &iEnd, &iPosition);

    if( rc==SQLITE_OK ){
      nByte = sizeof(Fts3Expr) + sizeof(Fts3Phrase) + nToken;
      pRet = (Fts3Expr *)sqlite3_malloc(nByte);
      pRet = (Fts3Expr *)fts3MallocZero(nByte);
      if( !pRet ){
        rc = SQLITE_NOMEM;
      }else{
        memset(pRet, 0, nByte);
        pRet->eType = FTSQUERY_PHRASE;
        pRet->pPhrase = (Fts3Phrase *)&pRet[1];
        pRet->pPhrase->nToken = 1;
        pRet->pPhrase->iColumn = iCol;
        pRet->pPhrase->aToken[0].n = nToken;
        pRet->pPhrase->aToken[0].z = (char *)&pRet->pPhrase[1];
        memcpy(pRet->pPhrase->aToken[0].z, zToken, nToken);

    pCursor->pTokenizer = pTokenizer;
    for(ii=0; rc==SQLITE_OK; ii++){
      const char *zToken;
      int nToken, iBegin, iEnd, iPos;
      rc = pModule->xNext(pCursor, &zToken, &nToken, &iBegin, &iEnd, &iPos);
      if( rc==SQLITE_OK ){
        int nByte = sizeof(Fts3Expr) + sizeof(Fts3Phrase);
        p = fts3ReallocOrFree(p, nByte+ii*sizeof(struct PhraseToken));
        p = fts3ReallocOrFree(p, nByte+ii*sizeof(Fts3PhraseToken));
        zTemp = fts3ReallocOrFree(zTemp, nTemp + nToken);
        if( !p || !zTemp ){
          goto no_mem;
        }
        if( ii==0 ){
          memset(p, 0, nByte);
          p->pPhrase = (Fts3Phrase *)&p[1];
        }
        p->pPhrase = (Fts3Phrase *)&p[1];
        memset(&p->pPhrase->aToken[ii], 0, sizeof(Fts3PhraseToken));
        p->pPhrase->nToken = ii+1;
        p->pPhrase->aToken[ii].n = nToken;
        memcpy(&zTemp[nTemp], zToken, nToken);
        nTemp += nToken;
        if( iEnd<nInput && zInput[iEnd]=='*' ){
          p->pPhrase->aToken[ii].isPrefix = 1;
        }else{

  }

  if( rc==SQLITE_DONE ){
    int jj;
    char *zNew = NULL;
    int nNew = 0;
    int nByte = sizeof(Fts3Expr) + sizeof(Fts3Phrase);
    nByte += (p?(p->pPhrase->nToken-1):0) * sizeof(struct PhraseToken);
    nByte += (p?(p->pPhrase->nToken-1):0) * sizeof(Fts3PhraseToken);
    p = fts3ReallocOrFree(p, nByte + nTemp);
    if( !p ){
      goto no_mem;
    }
    if( zTemp ){
      zNew = &(((char *)p)[nByte]);
      memcpy(zNew, zTemp, nTemp);

      ** the next byte must contain either whitespace, an open or close
      ** parenthesis, a quote character, or EOF. 
      */
      cNext = zInput[nKey];
      if( fts3isspace(cNext) 
       || cNext=='"' || cNext=='(' || cNext==')' || cNext==0
      ){
        pRet = (Fts3Expr *)sqlite3_malloc(sizeof(Fts3Expr));
        pRet = (Fts3Expr *)fts3MallocZero(sizeof(Fts3Expr));
        if( !pRet ){
          return SQLITE_NOMEM;
        }
        memset(pRet, 0, sizeof(Fts3Expr));
        pRet->eType = pKey->eType;
        pRet->nNear = nNear;
        *ppExpr = pRet;
        *pnConsumed = (int)((zInput - z) + nKey);
        return SQLITE_OK;
      }

    if( rc==SQLITE_OK ){
      int isPhrase;

      if( !sqlite3_fts3_enable_parentheses 
       && p->eType==FTSQUERY_PHRASE && p->pPhrase->isNot 
      ){
        /* Create an implicit NOT operator. */
        Fts3Expr *pNot = sqlite3_malloc(sizeof(Fts3Expr));
        Fts3Expr *pNot = fts3MallocZero(sizeof(Fts3Expr));
        if( !pNot ){
          sqlite3Fts3ExprFree(p);
          rc = SQLITE_NOMEM;
          goto exprparse_out;
        }
        memset(pNot, 0, sizeof(Fts3Expr));
        pNot->eType = FTSQUERY_NOT;
        pNot->pRight = p;
        if( pNotBranch ){
          pNot->pLeft = pNotBranch;
        }
        pNotBranch = pNot;
        p = pPrev;

          goto exprparse_out;
        }
  
        if( isPhrase && !isRequirePhrase ){
          /* Insert an implicit AND operator. */
          Fts3Expr *pAnd;
          assert( pRet && pPrev );
          pAnd = sqlite3_malloc(sizeof(Fts3Expr));
          pAnd = fts3MallocZero(sizeof(Fts3Expr));
          if( !pAnd ){
            sqlite3Fts3ExprFree(p);
            rc = SQLITE_NOMEM;
            goto exprparse_out;
          }
          memset(pAnd, 0, sizeof(Fts3Expr));
          pAnd->eType = FTSQUERY_AND;
          insertBinaryOperator(&pRet, pPrev, pAnd);
          pPrev = pAnd;
        }

        /* This test catches attempts to make either operand of a NEAR
        ** operator something other than a phrase. For example, either of

/*
** Used as an fts3ExprIterate() context when loading phrase doclists to
** Fts3Expr.aDoclist[]/nDoclist.
*/
typedef struct LoadDoclistCtx LoadDoclistCtx;
struct LoadDoclistCtx {
  Fts3Table *pTab;                /* FTS3 Table */
  Fts3Cursor *pCsr;               /* FTS3 Cursor */
  int nPhrase;                    /* Number of phrases seen so far */
  int nToken;                     /* Number of tokens seen so far */
};

/*
** The following types are used as part of the implementation of the 
** fts3BestSnippet() routine.

  UNUSED_PARAMETER(iPhrase);

  p->nPhrase++;
  p->nToken += pExpr->pPhrase->nToken;

  if( pExpr->isLoaded==0 ){
    rc = sqlite3Fts3ExprLoadDoclist(p->pTab, pExpr);
    rc = sqlite3Fts3ExprLoadDoclist(p->pCsr, pExpr);
    pExpr->isLoaded = 1;
    if( rc==SQLITE_OK ){
      rc = fts3ExprNearTrim(pExpr);
    }
  }

  return rc;

static int fts3ExprLoadDoclists(
  Fts3Cursor *pCsr,               /* Fts3 cursor for current query */
  int *pnPhrase,                  /* OUT: Number of phrases in query */
  int *pnToken                    /* OUT: Number of tokens in query */
){
  int rc;                         /* Return Code */
  LoadDoclistCtx sCtx = {0,0,0};  /* Context for fts3ExprIterate() */
  sCtx.pTab = (Fts3Table *)pCsr->base.pVtab;
  sCtx.pCsr = pCsr;
  rc = fts3ExprIterate(pCsr->pExpr, fts3ExprLoadDoclistsCb1, (void *)&sCtx);
  if( rc==SQLITE_OK ){
    (void)fts3ExprIterate(pCsr->pExpr, fts3ExprLoadDoclistsCb2, 0);
  }
  if( pnPhrase ) *pnPhrase = sCtx.nPhrase;
  if( pnToken ) *pnToken = sCtx.nToken;
  return rc;

*/
static int fts3ExprGlobalMatchinfoCb(
  Fts3Expr *pExpr,                /* Phrase expression node */
  int iPhrase,                    /* Phrase number (numbered from zero) */
  void *pCtx                      /* Pointer to MatchInfo structure */
){
  MatchInfo *p = (MatchInfo *)pCtx;
  Fts3Cursor *pCsr = p->pCursor;
  char *pCsr;
  char *pIter;
  char *pEnd;
  char *pFree = 0;
  const int iStart = 2 + (iPhrase * p->nCol * 3) + 1;

  assert( pExpr->isLoaded );
  assert( pExpr->eType==FTSQUERY_PHRASE );

  if( pCsr->pDeferred ){
    Fts3Phrase *pPhrase = pExpr->pPhrase;
    int ii;
    for(ii=0; ii<pPhrase->nToken; ii++){
      if( pPhrase->aToken[ii].bFulltext ) break;
    }
  /* Fill in the global hit count matrix row for this phrase. */
  pCsr = pExpr->aDoclist;
  pEnd = &pExpr->aDoclist[pExpr->nDoclist];
  while( pCsr<pEnd ){
    while( *pCsr++ & 0x80 );      /* Skip past docid. */
    fts3LoadColumnlistCounts(&pCsr, &p->aMatchinfo[iStart], 1);
    if( ii<pPhrase->nToken ){
      int nFree = 0;
      int rc = sqlite3Fts3ExprLoadFtDoclist(pCsr, pExpr, &pFree, &nFree);
      if( rc!=SQLITE_OK ) return rc;
      pIter = pFree;
      pEnd = &pFree[nFree];
    }else{
      int nDoc = p->aMatchinfo[2 + 3*p->nCol*p->aMatchinfo[0]];
      for(ii=0; ii<p->nCol; ii++){
        p->aMatchinfo[iStart + ii*3] = nDoc;
        p->aMatchinfo[iStart + ii*3 + 1] = nDoc;
      }
      return SQLITE_OK;
    }
  }else{
    pIter = pExpr->aDoclist;
    pEnd = &pExpr->aDoclist[pExpr->nDoclist];
  }

  /* Fill in the global hit count matrix row for this phrase. */
  while( pIter<pEnd ){
    while( *pIter++ & 0x80 );      /* Skip past docid. */
    fts3LoadColumnlistCounts(&pIter, &p->aMatchinfo[iStart], 1);
  }

  sqlite3_free(pFree);
  return SQLITE_OK;
}

/*
** fts3ExprIterate() callback used to collect the "local" matchinfo stats
** for a single query. The "local" stats are those elements of the matchinfo
** array that are different for each row returned by the query.

    sInfo.aMatchinfo = (u32 *)sqlite3_malloc(sizeof(u32)*nMatchinfo);
    if( !sInfo.aMatchinfo ){ 
      return SQLITE_NOMEM;
    }
    memset(sInfo.aMatchinfo, 0, sizeof(u32)*nMatchinfo);


    /* First element of match-info is the number of phrases in the query */
    sInfo.aMatchinfo[0] = nPhrase;
    sInfo.aMatchinfo[1] = sInfo.nCol;
    (void)fts3ExprIterate(pCsr->pExpr, fts3ExprGlobalMatchinfoCb,(void*)&sInfo);
    if( pTab->bHasDocsize ){
      int ofst = 2 + 3*sInfo.aMatchinfo[0]*sInfo.aMatchinfo[1];
      rc = sqlite3Fts3MatchinfoDocsizeGlobal(pCsr, &sInfo.aMatchinfo[ofst]);
    }
    (void)fts3ExprIterate(pCsr->pExpr, fts3ExprGlobalMatchinfoCb,(void*)&sInfo);
    pCsr->aMatchinfo = sInfo.aMatchinfo;
    pCsr->isMatchinfoNeeded = 1;
  }

  sInfo.aMatchinfo = pCsr->aMatchinfo;
  if( rc==SQLITE_OK && pCsr->isMatchinfoNeeded ){
    (void)fts3ExprIterate(pCsr->pExpr, fts3ExprLocalMatchinfoCb, (void*)&sInfo);

  for(i=0; i<nSnippet && rc==SQLITE_OK; i++){
    rc = fts3SnippetText(pCsr, &aSnippet[i], 
        i, (i==nSnippet-1), nFToken, zStart, zEnd, zEllipsis, &res
    );
  }

 snippet_out:
  sqlite3Fts3SegmentsClose(pTab);
  if( rc!=SQLITE_OK ){
    sqlite3_result_error_code(pCtx, rc);
    sqlite3_free(res.z);
  }else{
    sqlite3_result_text(pCtx, res.z, -1, sqlite3_free);
  }
}

    pMod->xClose(pC);
    if( rc!=SQLITE_OK ) goto offsets_out;
  }

 offsets_out:
  sqlite3_free(sCtx.aTerm);
  assert( rc!=SQLITE_DONE );
  sqlite3Fts3SegmentsClose(pTab);
  if( rc!=SQLITE_OK ){
    sqlite3_result_error_code(pCtx,  rc);
    sqlite3_free(res.z);
  }else{
    sqlite3_result_text(pCtx, res.z, res.n-1, sqlite3_free);
  }
  return;
}

/*
** Implementation of matchinfo() function.
*/
void sqlite3Fts3Matchinfo(sqlite3_context *pContext, Fts3Cursor *pCsr){
  int rc;
  if( !pCsr->pExpr ){
    sqlite3_result_blob(pContext, "", 0, SQLITE_STATIC);
    return;
  }
  rc = fts3GetMatchinfo(pCsr);
  sqlite3Fts3SegmentsClose((Fts3Table *)pCsr->base.pVtab );
  if( rc!=SQLITE_OK ){
    sqlite3_result_error_code(pContext, rc);
  }else{
    Fts3Table *pTab = (Fts3Table*)pCsr->base.pVtab;
    int n = sizeof(u32)*(2+pCsr->aMatchinfo[0]*pCsr->aMatchinfo[1]*3);
    if( pTab->bHasDocsize ){
      n += sizeof(u32)*(1 + 2*pTab->nColumn);
    }
    sqlite3_result_blob(pContext, pCsr->aMatchinfo, n, SQLITE_TRANSIENT);
  }
}

#endif

  char *aData;
  int nSpace;
  sqlite3_int64 iLastDocid;
  sqlite3_int64 iLastCol;
  sqlite3_int64 iLastPos;
};


/*
** Each cursor has a (possibly empty) linked list of the following objects.
*/
struct Fts3DeferredToken {
  Fts3PhraseToken *pToken;        /* Pointer to corresponding expr token */
  int iCol;                       /* Column token must occur in */
  Fts3DeferredToken *pNext;       /* Next in list of deferred tokens */
  PendingList *pList;             /* Doclist is assembled here */
};

/*
** An instance of this structure is used to iterate through the terms on
** a contiguous set of segment b-tree leaf nodes. Although the details of
** this structure are only manipulated by code in this file, opaque handles
** of type Fts3SegReader* are also used by code in fts3.c to iterate through
** terms when querying the full-text index. See functions:
**
**   sqlite3Fts3SegReaderNew()
**   sqlite3Fts3SegReaderFree()
**   sqlite3Fts3SegReaderCost()
**   sqlite3Fts3SegReaderIterate()
**
** Methods used to manipulate Fts3SegReader structures:
**
**   fts3SegReaderNext()
**   fts3SegReaderFirstDocid()
**   fts3SegReaderNextDocid()
*/
struct Fts3SegReader {
  int iIdx;                       /* Index within level, or 0x7FFFFFFF for PT */

  sqlite3_int64 iStartBlock;
  sqlite3_int64 iEndBlock;
  sqlite3_stmt *pStmt;            /* SQL Statement to access leaf nodes */
  sqlite3_int64 iStartBlock;      /* Rowid of first leaf block to traverse */
  sqlite3_int64 iLeafEndBlock;    /* Rowid of final leaf block to traverse */
  sqlite3_int64 iEndBlock;        /* Rowid of final block in segment (or 0) */
  sqlite3_int64 iCurrentBlock;    /* Current leaf block (or 0) */

  char *aNode;                    /* Pointer to node data (or NULL) */
  int nNode;                      /* Size of buffer at aNode (or 0) */
  int nTermAlloc;                 /* Allocated size of zTerm buffer */
  Fts3HashElem **ppNextElem;

  /* Variables set by fts3SegReaderNext(). These may be read directly
  ** by the caller. They are valid from the time SegmentReaderNew() returns
  ** until SegmentReaderNext() returns something other than SQLITE_OK
  ** (i.e. SQLITE_DONE).
  */
  int nTerm;                      /* Number of bytes in current term */
  char *zTerm;                    /* Pointer to current term */
  int nTermAlloc;                 /* Allocated size of zTerm buffer */
  char *aDoclist;                 /* Pointer to doclist of current entry */
  int nDoclist;                   /* Size of doclist in current entry */

  /* The following variables are used to iterate through the current doclist */
  char *pOffsetList;
  sqlite3_int64 iDocid;
};

#define fts3SegReaderIsPending(p) ((p)->ppNextElem!=0)
#define fts3SegReaderIsRootOnly(p) ((p)->aNode==(char *)&(p)[1])

/*
** An instance of this structure is used to create a segment b-tree in the
** database. The internal details of this type are only accessed by the
** following functions:
**
**   fts3SegWriterAdd()

#define SQL_SELECT_LEVEL              12
#define SQL_SELECT_ALL_LEVEL          13
#define SQL_SELECT_LEVEL_COUNT        14
#define SQL_SELECT_SEGDIR_COUNT_MAX   15
#define SQL_DELETE_SEGDIR_BY_LEVEL    16
#define SQL_DELETE_SEGMENTS_RANGE     17
#define SQL_CONTENT_INSERT            18
#define SQL_GET_BLOCK                 19
#define SQL_DELETE_DOCSIZE            20
#define SQL_REPLACE_DOCSIZE           21
#define SQL_SELECT_DOCSIZE            22
#define SQL_SELECT_DOCTOTAL           23
#define SQL_REPLACE_DOCTOTAL          24
#define SQL_DELETE_DOCSIZE            19
#define SQL_REPLACE_DOCSIZE           20
#define SQL_SELECT_DOCSIZE            21
#define SQL_SELECT_DOCTOTAL           22
#define SQL_REPLACE_DOCTOTAL          23

/*
** This function is used to obtain an SQLite prepared statement handle
** for the statement identified by the second argument. If successful,
** *pp is set to the requested statement handle and SQLITE_OK returned.
** Otherwise, an SQLite error code is returned and *pp is set to 0.
**

/* 14 */  "SELECT count(*) FROM %Q.'%q_segdir' WHERE level = ?",
/* 15 */  "SELECT count(*), max(level) FROM %Q.'%q_segdir'",

/* 16 */  "DELETE FROM %Q.'%q_segdir' WHERE level = ?",
/* 17 */  "DELETE FROM %Q.'%q_segments' WHERE blockid BETWEEN ? AND ?",
/* 18 */  "INSERT INTO %Q.'%q_content' VALUES(%z)",
/* 19 */  "SELECT block FROM %Q.'%q_segments' WHERE blockid = ?",
/* 20 */  "DELETE FROM %Q.'%q_docsize' WHERE docid = ?",
/* 21 */  "REPLACE INTO %Q.'%q_docsize' VALUES(?,?)",
/* 22 */  "SELECT size FROM %Q.'%q_docsize' WHERE docid=?",
/* 23 */  "SELECT value FROM %Q.'%q_stat' WHERE id=0",
/* 24 */  "REPLACE INTO %Q.'%q_stat' VALUES(0,?)",
/* 19 */  "DELETE FROM %Q.'%q_docsize' WHERE docid = ?",
/* 20 */  "REPLACE INTO %Q.'%q_docsize' VALUES(?,?)",
/* 21 */  "SELECT size FROM %Q.'%q_docsize' WHERE docid=?",
/* 22 */  "SELECT value FROM %Q.'%q_stat' WHERE id=0",
/* 23 */  "REPLACE INTO %Q.'%q_stat' VALUES(0,?)",
  };
  int rc = SQLITE_OK;
  sqlite3_stmt *pStmt;

  assert( SizeofArray(azSql)==SizeofArray(p->aStmt) );
  assert( eStmt<SizeofArray(azSql) && eStmt>=0 );
  

    sqlite3_step(pStmt);
    rc = sqlite3_reset(pStmt);
  }
  *pRC = rc;
}


/*
** Read a single block from the %_segments table. If the specified block
** does not exist, return SQLITE_CORRUPT. If some other error (malloc, IO 
** etc.) occurs, return the appropriate SQLite error code.
**
** Otherwise, if successful, set *pzBlock to point to a buffer containing
** the block read from the database, and *pnBlock to the size of the read
** block in bytes.
**
** WARNING: The returned buffer is only valid until the next call to 
** sqlite3Fts3ReadBlock().
*/
int sqlite3Fts3ReadBlock(
  Fts3Table *p,
  sqlite3_int64 iBlock,
  char const **pzBlock,
  int *pnBlock
){
  sqlite3_stmt *pStmt;
  int rc = fts3SqlStmt(p, SQL_GET_BLOCK, &pStmt, 0);
  if( rc!=SQLITE_OK ) return rc;
  sqlite3_reset(pStmt);

  if( pzBlock ){
    sqlite3_bind_int64(pStmt, 1, iBlock);
    rc = sqlite3_step(pStmt); 
    if( rc!=SQLITE_ROW ){
      return (rc==SQLITE_DONE ? SQLITE_CORRUPT : rc);
    }
  
    *pnBlock = sqlite3_column_bytes(pStmt, 0);
    *pzBlock = (char *)sqlite3_column_blob(pStmt, 0);
    if( sqlite3_column_type(pStmt, 0)!=SQLITE_BLOB ){
      return SQLITE_CORRUPT;
    }
  }
  return SQLITE_OK;
}

/*
** This function ensures that the caller has obtained a shared-cache
** table-lock on the %_content table. This is required before reading
** data from the fts3 table. If this lock is not acquired first, then
** the caller may end up holding read-locks on the %_segments and %_segdir
** tables, but no read-lock on the %_content table. If this happens 
** a second connection will be able to write to the fts3 table, but

** Tokenize the nul-terminated string zText and add all tokens to the
** pending-terms hash-table. The docid used is that currently stored in
** p->iPrevDocid, and the column is specified by argument iCol.
**
** If successful, SQLITE_OK is returned. Otherwise, an SQLite error code.
*/
static int fts3PendingTermsAdd(
  Fts3Table *p,          /* FTS table into which text will be inserted */
  const char *zText,     /* Text of document to be inseted */
  int iCol,              /* Column number into which text is inserted */
  u32 *pnWord            /* OUT: Number of tokens inserted */
  Fts3Table *p,                   /* Table into which text will be inserted */
  const char *zText,              /* Text of document to be inserted */
  int iCol,                       /* Column into which text is being inserted */
  u32 *pnWord                     /* OUT: Number of tokens inserted */
){
  int rc;
  int iStart;
  int iEnd;
  int iPos;
  int nWord = 0;

    int rc = sqlite3Fts3PendingTermsFlush(p);
    if( rc!=SQLITE_OK ) return rc;
  }
  p->iPrevDocid = iDocid;
  return SQLITE_OK;
}

/*
** Discard the contents of the pending-terms hash table. 
*/
void sqlite3Fts3PendingTermsClear(Fts3Table *p){
  Fts3HashElem *pElem;
  for(pElem=fts3HashFirst(&p->pendingTerms); pElem; pElem=fts3HashNext(pElem)){
    sqlite3_free(fts3HashData(pElem));
  }
  fts3HashClear(&p->pendingTerms);
  p->nPendingData = 0;

    const char *zText = (const char *)sqlite3_value_text(apVal[i]);
    if( zText ){
      int rc = fts3PendingTermsAdd(p, zText, i-2, &aSz[i-2]);
      if( rc!=SQLITE_OK ){
        return rc;
      }
    }
    aSz[p->nColumn] += sqlite3_value_bytes(apVal[i]);
  }
  return SQLITE_OK;
}

/*
** This function is called by the xUpdate() method for an INSERT operation.
** The apVal parameter is passed a copy of the apVal argument passed by

}

/*
** The first element in the apVal[] array is assumed to contain the docid
** (an integer) of a row about to be deleted. Remove all terms from the
** full-text index.
*/
static void fts3DeleteTerms(
static void fts3DeleteTerms( 
  int *pRC,               /* Result code */
  Fts3Table *p,           /* The FTS table to delete from */
  sqlite3_value **apVal,  /* apVal[] contains the docid to be deleted */
  u32 *aSz                /* Sizes of deleted document written here */
){
  int rc;
  sqlite3_stmt *pSelect;

        const char *zText = (const char *)sqlite3_column_text(pSelect, i);
        rc = fts3PendingTermsAdd(p, zText, -1, &aSz[i-1]);
        if( rc!=SQLITE_OK ){
          sqlite3_reset(pSelect);
          *pRC = rc;
          return;
        }
        aSz[p->nColumn] += sqlite3_column_bytes(pSelect, i);
      }
    }
    rc = sqlite3_reset(pSelect);
  }else{
    sqlite3_reset(pSelect);
  }
  *pRC = rc;

    }else{
      *piIdx = iNext;
    }
  }

  return rc;
}

/*
** The %_segments table is declared as follows:
**
**   CREATE TABLE %_segments(blockid INTEGER PRIMARY KEY, block BLOB)
**
** This function reads data from a single row of the %_segments table. The
** specific row is identified by the iBlockid parameter. If paBlob is not
** NULL, then a buffer is allocated using sqlite3_malloc() and populated
** with the contents of the blob stored in the "block" column of the 
** identified table row is. Whether or not paBlob is NULL, *pnBlob is set
** to the size of the blob in bytes before returning.
**
** If an error occurs, or the table does not contain the specified row,
** an SQLite error code is returned. Otherwise, SQLITE_OK is returned. If
** paBlob is non-NULL, then it is the responsibility of the caller to
** eventually free the returned buffer.
**
** This function may leave an open sqlite3_blob* handle in the
** Fts3Table.pSegments variable. This handle is reused by subsequent calls
** to this function. The handle may be closed by calling the
** sqlite3Fts3SegmentsClose() function. Reusing a blob handle is a handy
** performance improvement, but the blob handle should always be closed
** before control is returned to the user (to prevent a lock being held
** on the database file for longer than necessary). Thus, any virtual table
** method (xFilter etc.) that may directly or indirectly call this function
** must call sqlite3Fts3SegmentsClose() before returning.
*/
int sqlite3Fts3ReadBlock(
  Fts3Table *p,                   /* FTS3 table handle */
  sqlite3_int64 iBlockid,         /* Access the row with blockid=$iBlockid */
  char **paBlob,                  /* OUT: Blob data in malloc'd buffer */
  int *pnBlob                     /* OUT: Size of blob data */
){
  int rc;                         /* Return code */

  /* pnBlob must be non-NULL. paBlob may be NULL or non-NULL. */
  assert( pnBlob);

  if( p->pSegments ){
    rc = sqlite3_blob_reopen(p->pSegments, iBlockid);
  }else{
    if( 0==p->zSegmentsTbl ){
      p->zSegmentsTbl = sqlite3_mprintf("%s_segments", p->zName);
      if( 0==p->zSegmentsTbl ) return SQLITE_NOMEM;
    }
    rc = sqlite3_blob_open(
       p->db, p->zDb, p->zSegmentsTbl, "block", iBlockid, 0, &p->pSegments
    );
  }

  if( rc==SQLITE_OK ){
    int nByte = sqlite3_blob_bytes(p->pSegments);
    if( paBlob ){
      char *aByte = sqlite3_malloc(nByte);
      if( !aByte ){
        rc = SQLITE_NOMEM;
      }else{
        rc = sqlite3_blob_read(p->pSegments, aByte, nByte, 0);
        if( rc!=SQLITE_OK ){
          sqlite3_free(aByte);
          aByte = 0;
        }
      }
      *paBlob = aByte;
    }
    *pnBlob = nByte;
  }

  return rc;
}

/*
** Close the blob handle at p->pSegments, if it is open. See comments above
** the sqlite3Fts3ReadBlock() function for details.
*/
void sqlite3Fts3SegmentsClose(Fts3Table *p){
  sqlite3_blob_close(p->pSegments);
  p->pSegments = 0;
}

/*
** Move the iterator passed as the first argument to the next term in the
** segment. If successful, SQLITE_OK is returned. If there is no next term,
** SQLITE_DONE. Otherwise, an SQLite error code.
*/
static int fts3SegReaderNext(Fts3SegReader *pReader){
static int fts3SegReaderNext(Fts3Table *p, Fts3SegReader *pReader){
  char *pNext;                    /* Cursor variable */
  int nPrefix;                    /* Number of bytes in term prefix */
  int nSuffix;                    /* Number of bytes in term suffix */

  if( !pReader->aDoclist ){
    pNext = pReader->aNode;
  }else{
    pNext = &pReader->aDoclist[pReader->nDoclist];
  }

  if( !pNext || pNext>=&pReader->aNode[pReader->nNode] ){
    int rc;                       /* Return code from Fts3ReadBlock() */
    int rc;

    if( fts3SegReaderIsPending(pReader) ){
      Fts3HashElem *pElem = *(pReader->ppNextElem);
      if( pElem==0 ){
        pReader->aNode = 0;
      }else{
        PendingList *pList = (PendingList *)fts3HashData(pElem);
        pReader->zTerm = (char *)fts3HashKey(pElem);
        pReader->nTerm = fts3HashKeysize(pElem);
        pReader->nNode = pReader->nDoclist = pList->nData + 1;
        pReader->aNode = pReader->aDoclist = pList->aData;
        pReader->ppNextElem++;
        assert( pReader->aNode );
      }
      return SQLITE_OK;
    }

    if( !fts3SegReaderIsRootOnly(pReader) ){
    if( !pReader->pStmt ){
      pReader->aNode = 0;
      sqlite3_free(pReader->aNode);
    }
    pReader->aNode = 0;

    /* If iCurrentBlock>=iLeafEndBlock, this is an EOF condition. All leaf 
    ** blocks have already been traversed.  */
    assert( pReader->iCurrentBlock<=pReader->iLeafEndBlock );
    if( pReader->iCurrentBlock>=pReader->iLeafEndBlock ){
      return SQLITE_OK;
    }
    rc = sqlite3_step(pReader->pStmt);
    if( rc!=SQLITE_ROW ){
      pReader->aNode = 0;
      return (rc==SQLITE_DONE ? SQLITE_OK : rc);
    }
    pReader->nNode = sqlite3_column_bytes(pReader->pStmt, 0);
    pReader->aNode = (char *)sqlite3_column_blob(pReader->pStmt, 0);

    rc = sqlite3Fts3ReadBlock(
        p, ++pReader->iCurrentBlock, &pReader->aNode, &pReader->nNode
    );
    if( rc!=SQLITE_OK ) return rc;
    pNext = pReader->aNode;
  }
  
  pNext += sqlite3Fts3GetVarint32(pNext, &nPrefix);
  pNext += sqlite3Fts3GetVarint32(pNext, &nSuffix);

  if( nPrefix+nSuffix>pReader->nTermAlloc ){
    int nNew = (nPrefix+nSuffix)*2;
    char *zNew = sqlite3_realloc(pReader->zTerm, nNew);
    if( !zNew ){
      return SQLITE_NOMEM;
    }
    pReader->zTerm = zNew;
    pReader->nTermAlloc = nNew;
  }
  memcpy(&pReader->zTerm[nPrefix], pNext, nSuffix);
  pReader->nTerm = nPrefix+nSuffix;
  pNext += nSuffix;
  pNext += sqlite3Fts3GetVarint32(pNext, &pReader->nDoclist);
  assert( pNext<&pReader->aNode[pReader->nNode] );
  pReader->aDoclist = pNext;
  pReader->pOffsetList = 0;

  /* Check that the doclist does not appear to extend past the end of the
  ** b-tree node. And that the final byte of the doclist is either an 0x00 
  ** or 0x01. If either of these statements is untrue, then the data structure 
  ** is corrupt.
  */
  if( &pReader->aDoclist[pReader->nDoclist]>&pReader->aNode[pReader->nNode] 
   || (pReader->aDoclist[pReader->nDoclist-1]&0xFE)!=0
  ){
    return SQLITE_CORRUPT;
  }
  return SQLITE_OK;
}

/*
** Set the SegReader to point to the first docid in the doclist associated
** with the current term.
*/

    pReader->pOffsetList = 0;
  }else{
    sqlite3_int64 iDelta;
    pReader->pOffsetList = p + sqlite3Fts3GetVarint(p, &iDelta);
    pReader->iDocid += iDelta;
  }
}

/*
** This function is called to estimate the amount of data that will be 
** loaded from the disk If SegReaderIterate() is called on this seg-reader,
** in units of average document size.
** 
** This can be used as follows: If the caller has a small doclist that 
** contains references to N documents, and is considering merging it with
** a large doclist (size X "average documents"), it may opt not to load
** the large doclist if X>N.
*/
int sqlite3Fts3SegReaderCost(
  Fts3Cursor *pCsr,               /* FTS3 cursor handle */
  Fts3SegReader *pReader,         /* Segment-reader handle */
  int *pnCost                     /* IN/OUT: Number of bytes read */
){
  Fts3Table *p = (Fts3Table*)pCsr->base.pVtab;
  int rc = SQLITE_OK;             /* Return code */
  int nCost = 0;                  /* Cost in bytes to return */
  int pgsz = p->nPgsz;            /* Database page size */

  /* If this seg-reader is reading the pending-terms table, or if all data
  ** for the segment is stored on the root page of the b-tree, then the cost
  ** is zero. In this case all required data is already in main memory.
  */
  if( p->bHasDocsize 
   && !fts3SegReaderIsPending(pReader) 
   && !fts3SegReaderIsRootOnly(pReader) 
  ){
    int nBlob = 0;
    sqlite3_int64 iBlock;

    if( pCsr->nRowAvg==0 ){
      /* The average document size, which is required to calculate the cost
      ** of each doclist, has not yet been determined. Read the required 
      ** data from the %_stat table to calculate it.
      **
      ** Entry 0 of the %_stat table is a blob containing (nCol+1) FTS3 
      ** varints, where nCol is the number of columns in the FTS3 table.
      ** The first varint is the number of documents currently stored in
      ** the table. The following nCol varints contain the total amount of
      ** data stored in all rows of each column of the table, from left
      ** to right.
      */
      sqlite3_stmt *pStmt;
      rc = fts3SqlStmt(p, SQL_SELECT_DOCTOTAL, &pStmt, 0);
      if( rc ) return rc;
      if( sqlite3_step(pStmt)==SQLITE_ROW ){
        sqlite3_int64 nDoc = 0;
        sqlite3_int64 nByte = 0;
        const char *a = sqlite3_column_blob(pStmt, 0);
        if( a ){
          const char *pEnd = &a[sqlite3_column_bytes(pStmt, 0)];
          a += sqlite3Fts3GetVarint(a, &nDoc);
          while( a<pEnd ){
            a += sqlite3Fts3GetVarint(a, &nByte);
          }
        }

        pCsr->nRowAvg = (((nByte / nDoc) + pgsz - 1) / pgsz);
      }
      rc = sqlite3_reset(pStmt);
      if( rc!=SQLITE_OK || pCsr->nRowAvg==0 ) return rc;
    }

    /* Assume that a blob flows over onto overflow pages if it is larger
    ** than (pgsz-35) bytes in size (the file-format documentation
    ** confirms this).
    */
    for(iBlock=pReader->iStartBlock; iBlock<=pReader->iLeafEndBlock; iBlock++){
      rc = sqlite3Fts3ReadBlock(p, iBlock, 0, &nBlob);
      if( rc!=SQLITE_OK ) break;
      if( (nBlob+35)>pgsz ){
        int nOvfl = (nBlob + 34)/pgsz;
        nCost += ((nOvfl + pCsr->nRowAvg - 1)/pCsr->nRowAvg);
      }
    }
  }

  *pnCost += nCost;
  return rc;
}

/*
** Free all allocations associated with the iterator passed as the 
** second argument.
*/
void sqlite3Fts3SegReaderFree(Fts3Table *p, Fts3SegReader *pReader){
  if( pReader ){
    if( pReader->pStmt ){
  if( pReader && !fts3SegReaderIsPending(pReader) ){
    sqlite3_free(pReader->zTerm);
      /* Move the leaf-range SELECT statement to the aLeavesStmt[] array,
      ** so that it can be reused when required by another query.
      */
      assert( p->nLeavesStmt<p->nLeavesTotal );
      sqlite3_reset(pReader->pStmt);
      p->aLeavesStmt[p->nLeavesStmt++] = pReader->pStmt;
    }
    if( !fts3SegReaderIsPending(pReader) ){
      sqlite3_free(pReader->zTerm);
    if( !fts3SegReaderIsRootOnly(pReader) ){
      sqlite3_free(pReader->aNode);
    }
    sqlite3_free(pReader);
  }
  sqlite3_free(pReader);
}

/*
** Allocate a new SegReader object.
*/
int sqlite3Fts3SegReaderNew(
  Fts3Table *p,                   /* Virtual table handle */
  int iAge,                       /* Segment "age". */
  sqlite3_int64 iStartLeaf,       /* First leaf to traverse */
  sqlite3_int64 iEndLeaf,         /* Final leaf to traverse */
  sqlite3_int64 iEndBlock,        /* Final block of segment */
  const char *zRoot,              /* Buffer containing root node */
  int nRoot,                      /* Size of buffer containing root node */
  Fts3SegReader **ppReader        /* OUT: Allocated Fts3SegReader */
){
  int rc = SQLITE_OK;             /* Return code */
  Fts3SegReader *pReader;         /* Newly allocated SegReader object */
  int nExtra = 0;                 /* Bytes to allocate segment root node */

  assert( iStartLeaf<=iEndLeaf );
  if( iStartLeaf==0 ){
    nExtra = nRoot;
  }

  pReader = (Fts3SegReader *)sqlite3_malloc(sizeof(Fts3SegReader) + nExtra);
  if( !pReader ){
    return SQLITE_NOMEM;
  }
  memset(pReader, 0, sizeof(Fts3SegReader));
  pReader->iIdx = iAge;
  pReader->iStartBlock = iStartLeaf;
  pReader->iIdx = iAge;
  pReader->iLeafEndBlock = iEndLeaf;
  pReader->iEndBlock = iEndBlock;

  if( nExtra ){
    /* The entire segment is stored in the root node. */
    pReader->aNode = (char *)&pReader[1];
    pReader->nNode = nRoot;
    memcpy(pReader->aNode, zRoot, nRoot);
  }else{
    /* If the text of the SQL statement to iterate through a contiguous
    ** set of entries in the %_segments table has not yet been composed,
    ** compose it now.
    */
    if( !p->zSelectLeaves ){
      p->zSelectLeaves = sqlite3_mprintf(
          "SELECT block FROM %Q.'%q_segments' WHERE blockid BETWEEN ? AND ? "
          "ORDER BY blockid", p->zDb, p->zName
      );
      if( !p->zSelectLeaves ){
        rc = SQLITE_NOMEM;
        goto finished;
      }
    }

    pReader->iCurrentBlock = iStartLeaf-1;
    /* If there are no free statements in the aLeavesStmt[] array, prepare
    ** a new statement now. Otherwise, reuse a prepared statement from
    ** aLeavesStmt[].
    */
    if( p->nLeavesStmt==0 ){
      if( p->nLeavesTotal==p->nLeavesAlloc ){
        int nNew = p->nLeavesAlloc + 16;
        sqlite3_stmt **aNew = (sqlite3_stmt **)sqlite3_realloc(
            p->aLeavesStmt, nNew*sizeof(sqlite3_stmt *)
        );
        if( !aNew ){
          rc = SQLITE_NOMEM;
          goto finished;
        }
  }
        p->nLeavesAlloc = nNew;
        p->aLeavesStmt = aNew;
      }
      rc = sqlite3_prepare_v2(p->db, p->zSelectLeaves, -1, &pReader->pStmt, 0);
      if( rc!=SQLITE_OK ){
        goto finished;
      }
      p->nLeavesTotal++;
    }else{
      pReader->pStmt = p->aLeavesStmt[--p->nLeavesStmt];
    }

    /* Bind the start and end leaf blockids to the prepared SQL statement. */
    sqlite3_bind_int64(pReader->pStmt, 1, iStartLeaf);
    sqlite3_bind_int64(pReader->pStmt, 2, iEndLeaf);
  }
  rc = fts3SegReaderNext(pReader);
  rc = fts3SegReaderNext(p, pReader);

 finished:
  if( rc==SQLITE_OK ){
    *ppReader = pReader;
  }else{
    sqlite3Fts3SegReaderFree(p, pReader);
  }
  return rc;
}

    if( !pReader ){
      rc = SQLITE_NOMEM;
    }else{
      memset(pReader, 0, nByte);
      pReader->iIdx = 0x7FFFFFFF;
      pReader->ppNextElem = (Fts3HashElem **)&pReader[1];
      memcpy(pReader->ppNextElem, aElem, nElem*sizeof(Fts3HashElem *));
      fts3SegReaderNext(pReader);
      fts3SegReaderNext(p, pReader);
    }
  }

  if( isPrefix ){
    sqlite3_free(aElem);
  }
  *ppReader = pReader;

}

/*
** Add term zTerm to the SegmentNode. It is guaranteed that zTerm is larger
** (according to memcmp) than the previous term.
*/
static int fts3NodeAddTerm(
  Fts3Table *p,               /* Virtual table handle */
  Fts3Table *p,                   /* Virtual table handle */
  SegmentNode **ppTree,           /* IN/OUT: SegmentNode handle */ 
  int isCopyTerm,                 /* True if zTerm/nTerm is transient */
  const char *zTerm,              /* Pointer to buffer containing term */
  int nTerm                       /* Size of term in bytes */
){
  SegmentNode *pTree = *ppTree;
  int rc;

  */
  if( pFilter->zTerm ){
    int nTerm = pFilter->nTerm;
    const char *zTerm = pFilter->zTerm;
    for(i=0; i<nSegment; i++){
      Fts3SegReader *pSeg = apSegment[i];
      while( fts3SegReaderTermCmp(pSeg, zTerm, nTerm)<0 ){
        rc = fts3SegReaderNext(pSeg);
        rc = fts3SegReaderNext(p, pSeg);
        if( rc!=SQLITE_OK ) goto finished; }
    }
  }

  fts3SegReaderSort(apSegment, nSegment, nSegment, fts3SegReaderCmp);
  while( apSegment[0]->aNode ){
    int nTerm = apSegment[0]->nTerm;

    ** term (if such a term exists in the index) has already been made.
    */
    if( pFilter->zTerm && !isPrefix ){
      goto finished;
    }

    for(i=0; i<nMerge; i++){
      rc = fts3SegReaderNext(apSegment[i]);
      rc = fts3SegReaderNext(p, apSegment[i]);
      if( rc!=SQLITE_OK ) goto finished;
    }
    fts3SegReaderSort(apSegment, nSegment, nMerge, fts3SegReaderCmp);
  }

 finished:
  sqlite3_free(aBuffer);

** Otherwise, if successful, SQLITE_OK is returned. If an error occurs, 
** an SQLite error code is returned.
*/
static int fts3SegmentMerge(Fts3Table *p, int iLevel){
  int i;                          /* Iterator variable */
  int rc;                         /* Return code */
  int iIdx;                       /* Index of new segment */
  int iNewLevel;                  /* Level to create new segment at */
  int iNewLevel = 0;              /* Level to create new segment at */
  sqlite3_stmt *pStmt = 0;
  SegmentWriter *pWriter = 0;
  int nSegment = 0;               /* Number of segments being merged */
  Fts3SegReader **apSegment = 0;  /* Array of Segment iterators */
  Fts3SegReader *pPending = 0;    /* Iterator for pending-terms */
  Fts3SegFilter filter;           /* Segment term filter condition */

  sqlite3_bind_int64(pStmt, 1, p->iPrevDocid);
  sqlite3_bind_blob(pStmt, 2, pBlob, nBlob, sqlite3_free);
  sqlite3_step(pStmt);
  *pRC = sqlite3_reset(pStmt);
}

/*
** Update the 0 record of the %_stat table so that it holds a blob
** which contains the document count followed by the cumulative
** document sizes for all columns.
** Record 0 of the %_stat table contains a blob consisting of N varints,
** where N is the number of user defined columns in the fts3 table plus
** two. If nCol is the number of user defined columns, then values of the 
** varints are set as follows:
**
**   Varint 0:       Total number of rows in the table.
**
**   Varint 1..nCol: For each column, the total number of tokens stored in
**                   the column for all rows of the table.
**
**   Varint 1+nCol:  The total size, in bytes, of all text values in all
**                   columns of all rows of the table.
**
*/
static void fts3UpdateDocTotals(
  int *pRC,       /* The result code */
  Fts3Table *p,   /* Table being updated */
  u32 *aSzIns,    /* Size increases */
  u32 *aSzDel,    /* Size decreases */
  int nChng       /* Change in the number of documents */
  int *pRC,                       /* The result code */
  Fts3Table *p,                   /* Table being updated */
  u32 *aSzIns,                    /* Size increases */
  u32 *aSzDel,                    /* Size decreases */
  int nChng                       /* Change in the number of documents */
){
  char *pBlob;             /* Storage for BLOB written into %_stat */
  int nBlob;               /* Size of BLOB written into %_stat */
  u32 *a;                  /* Array of integers that becomes the BLOB */
  sqlite3_stmt *pStmt;     /* Statement for reading and writing */
  int i;                   /* Loop counter */
  int rc;                  /* Result code from subfunctions */

  const int nStat = p->nColumn+2;

  if( *pRC ) return;
  a = sqlite3_malloc( (sizeof(u32)+10)*(p->nColumn+1) );
  a = sqlite3_malloc( (sizeof(u32)+10)*nStat );
  if( a==0 ){
    *pRC = SQLITE_NOMEM;
    return;
  }
  pBlob = (char*)&a[p->nColumn+1];
  pBlob = (char*)&a[nStat];
  rc = fts3SqlStmt(p, SQL_SELECT_DOCTOTAL, &pStmt, 0);
  if( rc ){
    sqlite3_free(a);
    *pRC = rc;
    return;
  }
  if( sqlite3_step(pStmt)==SQLITE_ROW ){
    fts3DecodeIntArray(p->nColumn+1, a,
    fts3DecodeIntArray(nStat, a,
         sqlite3_column_blob(pStmt, 0),
         sqlite3_column_bytes(pStmt, 0));
  }else{
    memset(a, 0, sizeof(u32)*(p->nColumn+1) );
    memset(a, 0, sizeof(u32)*(nStat) );
  }
  sqlite3_reset(pStmt);
  if( nChng<0 && a[0]<(u32)(-nChng) ){
    a[0] = 0;
  }else{
    a[0] += nChng;
  }
  for(i=0; i<p->nColumn; i++){
  for(i=0; i<p->nColumn+1; i++){
    u32 x = a[i+1];
    if( x+aSzIns[i] < aSzDel[i] ){
      x = 0;
    }else{
      x = x + aSzIns[i] - aSzDel[i];
    }
    a[i+1] = x;
  }
  fts3EncodeIntArray(p->nColumn+1, a, pBlob, &nBlob);
  fts3EncodeIntArray(nStat, a, pBlob, &nBlob);
  rc = fts3SqlStmt(p, SQL_REPLACE_DOCTOTAL, &pStmt, 0);
  if( rc ){
    sqlite3_free(a);
    *pRC = rc;
    return;
  }
  sqlite3_bind_blob(pStmt, 1, pBlob, nBlob, SQLITE_STATIC);

  }else if( nVal>11 && 0==sqlite3_strnicmp(zVal, "maxpending=", 9) ){
    p->nMaxPendingData = atoi(&zVal[11]);
    rc = SQLITE_OK;
#endif
  }else{
    rc = SQLITE_ERROR;
  }

  sqlite3Fts3SegmentsClose(p);
  return rc;
}

/*
** Return the deferred doclist associated with deferred token pDeferred.
** This function assumes that sqlite3Fts3CacheDeferredDoclists() has already
** been called to allocate and populate the doclist.
*/
char *sqlite3Fts3DeferredDoclist(Fts3DeferredToken *pDeferred, int *pnByte){
  if( pDeferred->pList ){
    *pnByte = pDeferred->pList->nData;
    return pDeferred->pList->aData;
  }
  *pnByte = 0;
  return 0;
}

/*
** Helper fucntion for FreeDeferredDoclists(). This function removes all
** references to deferred doclists from within the tree of Fts3Expr 
** structures headed by 
*/
static void fts3DeferredDoclistClear(Fts3Expr *pExpr){
  if( pExpr ){
    fts3DeferredDoclistClear(pExpr->pLeft);
    fts3DeferredDoclistClear(pExpr->pRight);
    if( pExpr->isLoaded ){
      sqlite3_free(pExpr->aDoclist);
      pExpr->isLoaded = 0;
      pExpr->aDoclist = 0;
      pExpr->nDoclist = 0;
      pExpr->pCurrent = 0;
      pExpr->iCurrent = 0;
    }
  }
}

/*
** Delete all cached deferred doclists. Deferred doclists are cached
** (allocated) by the sqlite3Fts3CacheDeferredDoclists() function.
*/
void sqlite3Fts3FreeDeferredDoclists(Fts3Cursor *pCsr){
  Fts3DeferredToken *pDef;
  for(pDef=pCsr->pDeferred; pDef; pDef=pDef->pNext){
    sqlite3_free(pDef->pList);
    pDef->pList = 0;
  }
  if( pCsr->pDeferred ){
    fts3DeferredDoclistClear(pCsr->pExpr);
  }
}

/*
** Free all entries in the pCsr->pDeffered list. Entries are added to 
** this list using sqlite3Fts3DeferToken().
*/
void sqlite3Fts3FreeDeferredTokens(Fts3Cursor *pCsr){
  Fts3DeferredToken *pDef;
  Fts3DeferredToken *pNext;
  for(pDef=pCsr->pDeferred; pDef; pDef=pNext){
    pNext = pDef->pNext;
    sqlite3_free(pDef->pList);
    sqlite3_free(pDef);
  }
  pCsr->pDeferred = 0;
}

/*
** Generate deferred-doclists for all tokens in the pCsr->pDeferred list
** based on the row that pCsr currently points to.
**
** A deferred-doclist is like any other doclist with position information
** included, except that it only contains entries for a single row of the
** table, not for all rows.
*/
int sqlite3Fts3CacheDeferredDoclists(Fts3Cursor *pCsr){
  int rc = SQLITE_OK;             /* Return code */
  if( pCsr->pDeferred ){
    int i;                        /* Used to iterate through table columns */
    sqlite3_int64 iDocid;         /* Docid of the row pCsr points to */
    Fts3DeferredToken *pDef;      /* Used to iterate through deferred tokens */
  
    Fts3Table *p = (Fts3Table *)pCsr->base.pVtab;
    sqlite3_tokenizer *pT = p->pTokenizer;
    sqlite3_tokenizer_module const *pModule = pT->pModule;
   
    assert( pCsr->isRequireSeek==0 );
    iDocid = sqlite3_column_int64(pCsr->pStmt, 0);
  
    for(i=0; i<p->nColumn && rc==SQLITE_OK; i++){
      const char *zText = (const char *)sqlite3_column_text(pCsr->pStmt, i+1);
      sqlite3_tokenizer_cursor *pTC = 0;
  
      rc = pModule->xOpen(pT, zText, -1, &pTC);
      while( rc==SQLITE_OK ){
        char const *zToken;       /* Buffer containing token */
        int nToken;               /* Number of bytes in token */
        int iDum1, iDum2;         /* Dummy variables */
        int iPos;                 /* Position of token in zText */
  
        pTC->pTokenizer = pT;
        rc = pModule->xNext(pTC, &zToken, &nToken, &iDum1, &iDum2, &iPos);
        for(pDef=pCsr->pDeferred; pDef && rc==SQLITE_OK; pDef=pDef->pNext){
          Fts3PhraseToken *pPT = pDef->pToken;
          if( (pDef->iCol>=p->nColumn || pDef->iCol==i)
           && (pPT->n==nToken || (pPT->isPrefix && pPT->n<nToken))
           && (0==memcmp(zToken, pPT->z, pPT->n))
          ){
            fts3PendingListAppend(&pDef->pList, iDocid, i, iPos, &rc);
          }
        }
      }
      if( pTC ) pModule->xClose(pTC);
      if( rc==SQLITE_DONE ) rc = SQLITE_OK;
    }
  
    for(pDef=pCsr->pDeferred; pDef && rc==SQLITE_OK; pDef=pDef->pNext){
      if( pDef->pList ){
        rc = fts3PendingListAppendVarint(&pDef->pList, 0);
      }
    }
  }

  return rc;
}

/*
** Add an entry for token pToken to the pCsr->pDeferred list.
*/
int sqlite3Fts3DeferToken(
  Fts3Cursor *pCsr,               /* Fts3 table cursor */
  Fts3PhraseToken *pToken,        /* Token to defer */
  int iCol                        /* Column that token must appear in (or -1) */
){
  Fts3DeferredToken *pDeferred;
  pDeferred = sqlite3_malloc(sizeof(*pDeferred));
  if( !pDeferred ){
    return SQLITE_NOMEM;
  }
  memset(pDeferred, 0, sizeof(*pDeferred));
  pDeferred->pToken = pToken;
  pDeferred->pNext = pCsr->pDeferred; 
  pDeferred->iCol = iCol;
  pCsr->pDeferred = pDeferred;

  assert( pToken->pDeferred==0 );
  pToken->pDeferred = pDeferred;

  return SQLITE_OK;
}


/*
** This function does the work for the xUpdate method of FTS3 virtual
** tables.
*/
int sqlite3Fts3UpdateMethod(
  sqlite3_vtab *pVtab,            /* FTS3 vtab object */
  int nArg,                       /* Size of argument array */
  sqlite3_value **apVal,          /* Array of arguments */
  sqlite_int64 *pRowid            /* OUT: The affected (or effected) rowid */
){
  Fts3Table *p = (Fts3Table *)pVtab;
  int rc = SQLITE_OK;             /* Return Code */
  int isRemove = 0;               /* True for an UPDATE or DELETE */
  sqlite3_int64 iRemove = 0;      /* Rowid removed by UPDATE or DELETE */
  u32 *aSzIns;                    /* Sizes of inserted documents */
  u32 *aSzDel;                    /* Sizes of deleted documents */
  int nChng = 0;                  /* Net change in number of documents */

  assert( p->pSegments==0 );

  /* Allocate space to hold the change in document sizes */
  aSzIns = sqlite3_malloc( sizeof(aSzIns[0])*p->nColumn*2 );
  aSzIns = sqlite3_malloc( sizeof(aSzIns[0])*(p->nColumn+1)*2 );
  if( aSzIns==0 ) return SQLITE_NOMEM;
  aSzDel = &aSzIns[p->nColumn];
  memset(aSzIns, 0, sizeof(aSzIns[0])*p->nColumn*2);
  aSzDel = &aSzIns[p->nColumn+1];
  memset(aSzIns, 0, sizeof(aSzIns[0])*(p->nColumn+1)*2);

  /* If this is a DELETE or UPDATE operation, remove the old record. */
  if( sqlite3_value_type(apVal[0])!=SQLITE_NULL ){
    int isEmpty;
    int isEmpty = 0;
    rc = fts3IsEmpty(p, apVal, &isEmpty);
    if( rc==SQLITE_OK ){
      if( isEmpty ){
        /* Deleting this row means the whole table is empty. In this case
        ** delete the contents of all three tables and throw away any
        ** data in the pendingTerms hash table.
        */

  }

  if( p->bHasDocsize ){
    fts3UpdateDocTotals(&rc, p, aSzIns, aSzDel, nChng);
  }

  sqlite3_free(aSzIns);
  sqlite3Fts3SegmentsClose(p);
  return rc;
}

/* 
** Flush any data in the pending-terms hash table to disk. If successful,
** merge all segments in the database (including the new segment, if 
** there was any data to flush) into a single segment. 

        sqlite3Fts3PendingTermsClear(p);
      }
    }else{
      sqlite3_exec(p->db, "ROLLBACK TO fts3", 0, 0, 0);
      sqlite3_exec(p->db, "RELEASE fts3", 0, 0, 0);
    }
  }
  sqlite3Fts3SegmentsClose(p);
  return rc;
}

#endif

#--------------------------------------------------------------------------
# This script contains several sub-programs used to test FTS3/FTS4 
# performance. It does not run the queries directly, but generates SQL
# scripts that can be run using the shell tool.
#
# The following cases are tested:
#
#   1. Inserting documents into an FTS3 table.
#   2. Optimizing an FTS3 table (i.e. "INSERT INTO t1 VALUES('optimize')").
#   3. Deleting documents from an FTS3 table.
#   4. Querying FTS3 tables.
#

# Number of tokens in vocabulary. And number of tokens in each document.
#
set VOCAB_SIZE  2000
set DOC_SIZE     100

set NUM_INSERTS 100000
set NUM_SELECTS 1000

# Force everything in this script to be deterministic.
#
expr {srand(0)}

proc usage {} {
  puts stderr "Usage: $::argv0 <rows> <selects>"
  exit -1
}

proc sql {sql} {
  puts $::fd $sql
}


# Return a list of $nWord randomly generated tokens each between 2 and 10
# characters in length.
#
proc build_vocab {nWord} {
  set ret [list]
  set chars [list a b c d e f g h i j k l m n o p q r s t u v w x y z]
  for {set i 0} {$i<$nWord} {incr i} {
    set len [expr {int((rand()*9.0)+2)}]
    set term ""
    for {set j 0} {$j<$len} {incr j} {
      append term [lindex $chars [expr {int(rand()*[llength $chars])}]]
    }
    lappend ret $term
  }
  set ret
}

proc select_term {} {
  set n [llength $::vocab]
  set t [expr int(rand()*$n*3)]
  if {$t>=2*$n} { set t [expr {($t-2*$n)/100}] }
  if {$t>=$n} { set t [expr {($t-$n)/10}] }
  lindex $::vocab $t
}

proc select_doc {nTerm} {
  set ret [list]
  for {set i 0} {$i<$nTerm} {incr i} {
    lappend ret [select_term]
  }
  set ret
}

proc test_1 {nInsert} {
  sql "PRAGMA synchronous = OFF;"
  sql "DROP TABLE IF EXISTS t1;"
  sql "CREATE VIRTUAL TABLE t1 USING fts4;"
  for {set i 0} {$i < $nInsert} {incr i} {
    set doc [select_doc $::DOC_SIZE]
    sql "INSERT INTO t1 VALUES('$doc');"
  }
}

proc test_2 {} {
  sql "INSERT INTO t1(t1) VALUES('optimize');"
}

proc test_3 {nSelect} {
  for {set i 0} {$i < $nSelect} {incr i} {
    sql "SELECT count(*) FROM t1 WHERE t1 MATCH '[select_term]';"
  }
}

proc test_4 {nSelect} {
  for {set i 0} {$i < $nSelect} {incr i} {
    sql "SELECT count(*) FROM t1 WHERE t1 MATCH '[select_term] [select_term]';"
  }
}

if {[llength $argv]!=0} usage

set ::vocab [build_vocab $::VOCAB_SIZE]

set ::fd [open fts3speed_insert.sql w]
test_1 $NUM_INSERTS
close $::fd

set ::fd [open fts3speed_select.sql w]
test_3 $NUM_SELECTS
close $::fd

set ::fd [open fts3speed_select2.sql w]
test_4 $NUM_SELECTS
close $::fd

set ::fd [open fts3speed_optimize.sql w]
test_2
close $::fd

puts "Success. Created files:"
puts "  fts3speed_insert.sql"
puts "  fts3speed_select.sql"
puts "  fts3speed_select2.sql"
puts "  fts3speed_optimize.sql"

** (stored in BtCursor.aOverflow[]) is allocated and used by function
** accessPayload() (the worker function for sqlite3BtreeData() and
** sqlite3BtreePutData()).
*/
void sqlite3BtreeCacheOverflow(BtCursor *pCur){
  assert( cursorHoldsMutex(pCur) );
  assert( sqlite3_mutex_held(pCur->pBtree->db->mutex) );
  assert(!pCur->isIncrblobHandle);
  assert(!pCur->aOverflow);
  invalidateOverflowCache(pCur);
  pCur->isIncrblobHandle = 1;
}
#endif

/*
** Set both the "read version" (single byte at byte offset 18) and 
** "write version" (single byte at byte offset 19) fields in the database

  const char *zTable,
  const char *zColumn,
  sqlite3_int64 iRow,
  int flags,
  sqlite3_blob **ppBlob
);

/*
** CAPI3REF: Move a BLOB Handle to a New Row
**
** This function is used to move an existing blob handle so that it points
** to a different row of the same database table. The new row is identified
** by the rowid value passed as the second argument. Only the row can be
** changed, the database, table and column on which the blob handle is open
** remain the same. Moving an existing blob handle to a new row can be
** faster than closing the existing handle and opening a new one.
**
** The new row must meet the same criteria as for [sqlite3_blob_open()] -
** it must exist and there must be either a blob or text value stored in
** the nominated column. If the new row is not present in the table, or if
** it does not contain a blob or text value, or if another error occurs, an
** SQLite error code is returned and the blob handle is considered aborted.
** All subsequent calls to [sqlite3_blob_read()], [sqlite3_blob_write()] or
** [sqlite3_blob_reopen()] on an aborted blob handle immediately return
** SQLITE_ABORT.
**
** This function sets the database handle error code and message.
*/
SQLITE_EXPERIMENTAL int sqlite3_blob_reopen(sqlite3_blob *, sqlite3_int64);

/*
** CAPI3REF: Close A BLOB Handle
**
** ^Closes an open [BLOB handle].
**
** ^Closing a BLOB shall cause the current transaction to commit
** if there are no other BLOBs, no pending prepared statements, and the

  Tcl_SetObjResult(interp, pRet);

  return TCL_OK;
}
#endif

#ifndef SQLITE_OMIT_INCRBLOB

static int blobHandleFromObj(
  Tcl_Interp *interp, 
  Tcl_Obj *pObj,
  sqlite3_blob **ppBlob
){
  char *z;
  int n;

  z = Tcl_GetStringFromObj(pObj, &n);
  if( n==0 ){
    *ppBlob = 0;
  }else{
    int notUsed;
    Tcl_Channel channel;
    ClientData instanceData;
    
    channel = Tcl_GetChannel(interp, z, &notUsed);
    if( !channel ) return TCL_ERROR;

    Tcl_Flush(channel);
    Tcl_Seek(channel, 0, SEEK_SET);

    instanceData = Tcl_GetChannelInstanceData(channel);
    *ppBlob = *((sqlite3_blob **)instanceData);
  }

  return TCL_OK;
}

/*
** sqlite3_blob_bytes  CHANNEL
*/
static int test_blob_bytes(
  ClientData clientData, /* Not used */
  Tcl_Interp *interp,    /* The TCL interpreter that invoked this command */
  int objc,              /* Number of arguments */
  Tcl_Obj *CONST objv[]  /* Command arguments */
){
  sqlite3_blob *pBlob;
  int nByte;
  
  if( objc!=2 ){
    Tcl_WrongNumArgs(interp, 1, objv, "CHANNEL");
    return TCL_ERROR;
  }

  if( blobHandleFromObj(interp, objv[1], &pBlob) ) return TCL_ERROR;
  nByte = sqlite3_blob_bytes(pBlob);
  Tcl_SetObjResult(interp, Tcl_NewIntObj(nByte));

  return TCL_OK;
}

/*
** sqlite3_blob_close  CHANNEL
*/
static int test_blob_close(
  ClientData clientData, /* Not used */
  Tcl_Interp *interp,    /* The TCL interpreter that invoked this command */
  int objc,              /* Number of arguments */
  Tcl_Obj *CONST objv[]  /* Command arguments */
){
  sqlite3_blob *pBlob;
  int nByte;
  
  if( objc!=2 ){
    Tcl_WrongNumArgs(interp, 1, objv, "CHANNEL");
    return TCL_ERROR;
  }

  if( blobHandleFromObj(interp, objv[1], &pBlob) ) return TCL_ERROR;
  sqlite3_blob_close(pBlob);

  return TCL_OK;
}

/*
** sqlite3_blob_read  CHANNEL OFFSET N
**
**   This command is used to test the sqlite3_blob_read() in ways that
**   the Tcl channel interface does not. The first argument should
**   be the name of a valid channel created by the [incrblob] method

*/
static int test_blob_read(
  ClientData clientData, /* Not used */
  Tcl_Interp *interp,    /* The TCL interpreter that invoked this command */
  int objc,              /* Number of arguments */
  Tcl_Obj *CONST objv[]  /* Command arguments */
){
  Tcl_Channel channel;
  ClientData instanceData;
  sqlite3_blob *pBlob;
  int notUsed;
  int nByte;
  int iOffset;
  unsigned char *zBuf;
  int rc;
  
  if( objc!=4 ){
    Tcl_WrongNumArgs(interp, 1, objv, "CHANNEL OFFSET N");
    return TCL_ERROR;
  }

  channel = Tcl_GetChannel(interp, Tcl_GetString(objv[1]), &notUsed);
  if( !channel
   || TCL_OK!=Tcl_GetIntFromObj(interp, objv[2], &iOffset)
  if( blobHandleFromObj(interp, objv[1], &pBlob) ) return TCL_ERROR;
  if( TCL_OK!=Tcl_GetIntFromObj(interp, objv[2], &iOffset)
   || TCL_OK!=Tcl_GetIntFromObj(interp, objv[3], &nByte)
   || nByte<0 || iOffset<0
  ){ 
    return TCL_ERROR;
  }

  instanceData = Tcl_GetChannelInstanceData(channel);
  pBlob = *((sqlite3_blob **)instanceData);

  zBuf = (unsigned char *)Tcl_Alloc(nByte);
  rc = sqlite3_blob_read(pBlob, zBuf, nByte, iOffset);
  if( rc==SQLITE_OK ){
    Tcl_SetObjResult(interp, Tcl_NewByteArrayObj(zBuf, nByte));
  }else{
    Tcl_SetResult(interp, (char *)sqlite3TestErrorName(rc), TCL_VOLATILE);
  }

*/
static int test_blob_write(
  ClientData clientData, /* Not used */
  Tcl_Interp *interp,    /* The TCL interpreter that invoked this command */
  int objc,              /* Number of arguments */
  Tcl_Obj *CONST objv[]  /* Command arguments */
){
  Tcl_Channel channel;
  ClientData instanceData;
  sqlite3_blob *pBlob;
  int notUsed;
  int iOffset;
  int rc;

  unsigned char *zBuf;
  int nBuf;
  
  if( objc!=4 && objc!=5 ){
    Tcl_WrongNumArgs(interp, 1, objv, "CHANNEL OFFSET DATA ?NDATA?");
    return TCL_ERROR;
  }

  channel = Tcl_GetChannel(interp, Tcl_GetString(objv[1]), &notUsed);
  if( !channel || TCL_OK!=Tcl_GetIntFromObj(interp, objv[2], &iOffset) ){ 
  if( blobHandleFromObj(interp, objv[1], &pBlob) ) return TCL_ERROR;
  if( TCL_OK!=Tcl_GetIntFromObj(interp, objv[2], &iOffset) ){ 
    return TCL_ERROR;
  }

  instanceData = Tcl_GetChannelInstanceData(channel);
  pBlob = *((sqlite3_blob **)instanceData);

  zBuf = Tcl_GetByteArrayFromObj(objv[3], &nBuf);
  if( objc==5 && Tcl_GetIntFromObj(interp, objv[4], &nBuf) ){
    return TCL_ERROR;
  }
  rc = sqlite3_blob_write(pBlob, zBuf, nBuf, iOffset);
  if( rc!=SQLITE_OK ){
    Tcl_SetResult(interp, (char *)sqlite3TestErrorName(rc), TCL_VOLATILE);
  }

  return (rc==SQLITE_OK ? TCL_OK : TCL_ERROR);
}

static int test_blob_reopen(
  ClientData clientData, /* Not used */
  Tcl_Interp *interp,    /* The TCL interpreter that invoked this command */
  int objc,              /* Number of arguments */
  Tcl_Obj *CONST objv[]  /* Command arguments */
){
  Tcl_WideInt iRowid;
  sqlite3_blob *pBlob;
  int rc;

  unsigned char *zBuf;
  int nBuf;
  
  if( objc!=3 ){
    Tcl_WrongNumArgs(interp, 1, objv, "CHANNEL ROWID");
    return TCL_ERROR;
  }

  if( blobHandleFromObj(interp, objv[1], &pBlob) ) return TCL_ERROR;
  if( Tcl_GetWideIntFromObj(interp, objv[2], &iRowid) ) return TCL_ERROR;

  rc = sqlite3_blob_reopen(pBlob, iRowid);
  if( rc!=SQLITE_OK ){
    Tcl_SetResult(interp, (char *)sqlite3TestErrorName(rc), TCL_VOLATILE);
  }

  return (rc==SQLITE_OK ? TCL_OK : TCL_ERROR);
}

#endif

/*
** Usage: sqlite3_create_collation_v2 DB-HANDLE NAME CMP-PROC DEL-PROC
**
**   This Tcl proc is used for testing the experimental
**   sqlite3_create_collation_v2() interface.

     { "sqlite3_shared_cache_report", sqlite3BtreeSharedCacheReport, 0},
#endif
     { "sqlite3_libversion_number", test_libversion_number, 0  },
#ifdef SQLITE_ENABLE_COLUMN_METADATA
     { "sqlite3_table_column_metadata", test_table_column_metadata, 0  },
#endif
#ifndef SQLITE_OMIT_INCRBLOB
     { "sqlite3_blob_read",  test_blob_read, 0  },
     { "sqlite3_blob_write", test_blob_write, 0  },
     { "sqlite3_blob_read",   test_blob_read, 0  },
     { "sqlite3_blob_write",  test_blob_write, 0  },
     { "sqlite3_blob_reopen", test_blob_reopen, 0  },
     { "sqlite3_blob_bytes",  test_blob_bytes, 0  },
     { "sqlite3_blob_close",  test_blob_close, 0  },
#endif
     { "pcache_stats",       test_pcache_stats, 0  },
#ifdef SQLITE_ENABLE_UNLOCK_NOTIFY
     { "sqlite3_unlock_notify", test_unlock_notify, 0  },
#endif
     { "sqlite3_wal_checkpoint", test_wal_checkpoint, 0  },
     { "test_sqlite3_log",     test_sqlite3_log, 0  },

** Valid sqlite3_blob* handles point to Incrblob structures.
*/
typedef struct Incrblob Incrblob;
struct Incrblob {
  int flags;              /* Copy of "flags" passed to sqlite3_blob_open() */
  int nByte;              /* Size of open blob, in bytes */
  int iOffset;            /* Byte offset of blob in cursor data */
  int iCol;               /* Table column this handle is open on */
  BtCursor *pCsr;         /* Cursor pointing at blob row */
  sqlite3_stmt *pStmt;    /* Statement holding cursor open */
  sqlite3 *db;            /* The associated database */
};


/*
** This function is used by both blob_open() and blob_reopen(). It seeks
** the b-tree cursor associated with blob handle p to point to row iRow.
** If successful, SQLITE_OK is returned and subsequent calls to
** sqlite3_blob_read() or sqlite3_blob_write() access the specified row.
**
** If an error occurs, or if the specified row does not exist or does not
** contain a value of type TEXT or BLOB in the column nominated when the
** blob handle was opened, then an error code is returned and *pzErr may
** be set to point to a buffer containing an error message. It is the
** responsibility of the caller to free the error message buffer using
** sqlite3DbFree().
**
** If an error does occur, then the b-tree cursor is closed. All subsequent
** calls to sqlite3_blob_read(), blob_write() or blob_reopen() will 
** immediately return SQLITE_ABORT.
*/
static int blobSeekToRow(Incrblob *p, sqlite3_int64 iRow, char **pzErr){
  int rc;                         /* Error code */
  char *zErr = 0;                 /* Error message */
  Vdbe *v = (Vdbe *)p->pStmt;

  /* Set the value of the SQL statements only variable to integer iRow. 
  ** This is done directly instead of using sqlite3_bind_int64() to avoid 
  ** triggering asserts related to mutexes.
  */
  assert( v->aVar[0].flags&MEM_Int );
  v->aVar[0].u.i = iRow;

  rc = sqlite3_step(p->pStmt);
  if( rc==SQLITE_ROW ){
    u32 type = v->apCsr[0]->aType[p->iCol];
    if( type<12 ){
      zErr = sqlite3MPrintf(p->db, "cannot open value of type %s",
          type==0?"null": type==7?"real": "integer"
      );
      rc = SQLITE_ERROR;
      sqlite3_finalize(p->pStmt);
      p->pStmt = 0;
    }else{
      p->iOffset = v->apCsr[0]->aOffset[p->iCol];
      p->nByte = sqlite3VdbeSerialTypeLen(type);
      p->pCsr =  v->apCsr[0]->pCursor;
      sqlite3BtreeEnterCursor(p->pCsr);
      sqlite3BtreeCacheOverflow(p->pCsr);
      sqlite3BtreeLeaveCursor(p->pCsr);
    }
  }

  if( rc==SQLITE_ROW ){
    rc = SQLITE_OK;
  }else if( p->pStmt ){
    rc = sqlite3_finalize(p->pStmt);
    p->pStmt = 0;
    if( rc==SQLITE_OK ){
      zErr = sqlite3MPrintf(p->db, "no such rowid: %lld", iRow);
      rc = SQLITE_ERROR;
    }else{
      zErr = sqlite3MPrintf(p->db, "%s", sqlite3_errmsg(p->db));
    }
  }

  assert( rc!=SQLITE_OK || zErr==0 );
  assert( rc!=SQLITE_ROW && rc!=SQLITE_DONE );

  *pzErr = zErr;
  return rc;
}

/*
** Open a blob handle.
*/
int sqlite3_blob_open(
  sqlite3* db,            /* The database connection */
  const char *zDb,        /* The attached database containing the blob */
  const char *zTable,     /* The table containing the blob */

    {OP_TableLock, 0, 0, 0},       /* 2: Acquire a read or write lock */

    /* One of the following two instructions is replaced by an OP_Noop. */
    {OP_OpenRead, 0, 0, 0},        /* 3: Open cursor 0 for reading */
    {OP_OpenWrite, 0, 0, 0},       /* 4: Open cursor 0 for read/write */

    {OP_Variable, 1, 1, 1},        /* 5: Push the rowid to the stack */
    {OP_NotExists, 0, 9, 1},       /* 6: Seek the cursor */
    {OP_NotExists, 0, 10, 1},      /* 6: Seek the cursor */
    {OP_Column, 0, 0, 1},          /* 7  */
    {OP_ResultRow, 1, 0, 0},       /* 8  */
    {OP_Goto, 0, 5, 0},            /* 9  */
    {OP_Close, 0, 0, 0},           /* 9  */
    {OP_Halt, 0, 0, 0},            /* 10 */
    {OP_Close, 0, 0, 0},           /* 10 */
    {OP_Halt, 0, 0, 0},            /* 11 */
  };

  Vdbe *v = 0;
  int rc = SQLITE_OK;
  char *zErr = 0;
  Table *pTab;
  Parse *pParse;
  Parse *pParse = 0;
  Incrblob *pBlob = 0;

  flags = !!flags;                /* flags = (flags ? 1 : 0); */
  *ppBlob = 0;

  sqlite3_mutex_enter(db->mutex);

  pBlob = (Incrblob *)sqlite3DbMallocZero(db, sizeof(Incrblob));
  if( !pBlob ) goto blob_open_out;
  pParse = sqlite3StackAllocRaw(db, sizeof(*pParse));
  if( pParse==0 ){
    rc = SQLITE_NOMEM;
    goto blob_open_out;
  }
  if( !pParse ) goto blob_open_out;

  do {
    memset(pParse, 0, sizeof(Parse));
    pParse->db = db;
    sqlite3DbFree(db, zErr);
    zErr = 0;

    sqlite3BtreeEnterAll(db);
    pTab = sqlite3LocateTable(pParse, 0, zTable, zDb);
    if( pTab && IsVirtual(pTab) ){
      pTab = 0;
      sqlite3ErrorMsg(pParse, "cannot open virtual table: %s", zTable);
    }

      }
      rc = SQLITE_ERROR;
      sqlite3BtreeLeaveAll(db);
      goto blob_open_out;
    }

    /* Now search pTab for the exact column. */
    for(iCol=0; iCol < pTab->nCol; iCol++) {
    for(iCol=0; iCol<pTab->nCol; iCol++) {
      if( sqlite3StrICmp(pTab->aCol[iCol].zName, zColumn)==0 ){
        break;
      }
    }
    if( iCol==pTab->nCol ){
      sqlite3DbFree(db, zErr);
      zErr = sqlite3MPrintf(db, "no such column: \"%s\"", zColumn);

        zErr = sqlite3MPrintf(db, "cannot open %s column for writing", zFault);
        rc = SQLITE_ERROR;
        sqlite3BtreeLeaveAll(db);
        goto blob_open_out;
      }
    }

    v = sqlite3VdbeCreate(db);
    if( v ){
    pBlob->pStmt = (sqlite3_stmt *)sqlite3VdbeCreate(db);
    assert( pBlob->pStmt || db->mallocFailed );
    if( pBlob->pStmt ){
      Vdbe *v = (Vdbe *)pBlob->pStmt;
      int iDb = sqlite3SchemaToIndex(db, pTab->pSchema);

      sqlite3VdbeAddOpList(v, sizeof(openBlob)/sizeof(VdbeOpList), openBlob);
      flags = !!flags;                 /* flags = (flags ? 1 : 0); */


      /* Configure the OP_Transaction */
      sqlite3VdbeChangeP1(v, 0, iDb);
      sqlite3VdbeChangeP2(v, 0, flags);

      /* Configure the OP_VerifyCookie */
      sqlite3VdbeChangeP1(v, 1, iDb);

      sqlite3VdbeChangeP4(v, 3+flags, SQLITE_INT_TO_PTR(pTab->nCol+1),P4_INT32);
      sqlite3VdbeChangeP2(v, 7, pTab->nCol);
      if( !db->mallocFailed ){
        sqlite3VdbeMakeReady(v, 1, 1, 1, 0, 0, 0);
      }
    }
   
    pBlob->flags = flags;
    pBlob->iCol = iCol;
    pBlob->db = db;
    sqlite3BtreeLeaveAll(db);
    if( db->mallocFailed ){
      goto blob_open_out;
    }

    sqlite3_bind_int64((sqlite3_stmt *)v, 1, iRow);
    sqlite3_bind_int64(pBlob->pStmt, 1, iRow);
    rc = sqlite3_step((sqlite3_stmt *)v);
    if( rc!=SQLITE_ROW ){
      nAttempt++;
      rc = sqlite3_finalize((sqlite3_stmt *)v);
      sqlite3DbFree(db, zErr);
    rc = blobSeekToRow(pBlob, iRow, &zErr);
      zErr = sqlite3MPrintf(db, "%s", sqlite3_errmsg(db));
      v = 0;
    }
  } while( nAttempt<5 && rc==SQLITE_SCHEMA );
  } while( (++nAttempt)<5 && rc==SQLITE_SCHEMA );

  if( rc==SQLITE_ROW ){
    /* The row-record has been opened successfully. Check that the
    ** column in question contains text or a blob. If it contains
    ** text, it is up to the caller to get the encoding right.
    */
    Incrblob *pBlob;
    u32 type = v->apCsr[0]->aType[iCol];

    if( type<12 ){
      sqlite3DbFree(db, zErr);
      zErr = sqlite3MPrintf(db, "cannot open value of type %s",
          type==0?"null": type==7?"real": "integer"
      );
      rc = SQLITE_ERROR;
      goto blob_open_out;
blob_open_out:
    }
    pBlob = (Incrblob *)sqlite3DbMallocZero(db, sizeof(Incrblob));
    if( db->mallocFailed ){
  if( rc==SQLITE_OK && db->mallocFailed==0 ){
      sqlite3DbFree(db, pBlob);
      goto blob_open_out;
    }
    pBlob->flags = flags;
    pBlob->pCsr =  v->apCsr[0]->pCursor;
    sqlite3BtreeEnterCursor(pBlob->pCsr);
    sqlite3BtreeCacheOverflow(pBlob->pCsr);
    sqlite3BtreeLeaveCursor(pBlob->pCsr);
    pBlob->pStmt = (sqlite3_stmt *)v;
    pBlob->iOffset = v->apCsr[0]->aOffset[iCol];
    pBlob->nByte = sqlite3VdbeSerialTypeLen(type);
    pBlob->db = db;
    *ppBlob = (sqlite3_blob *)pBlob;
    rc = SQLITE_OK;
  }else if( rc==SQLITE_OK ){
    sqlite3DbFree(db, zErr);
  }else{
    if( pBlob && pBlob->pStmt ) sqlite3VdbeFinalize((Vdbe *)pBlob->pStmt);
    sqlite3DbFree(db, pBlob);
    zErr = sqlite3MPrintf(db, "no such rowid: %lld", iRow);
    rc = SQLITE_ERROR;
  }

blob_open_out:
  if( v && (rc!=SQLITE_OK || db->mallocFailed) ){
    sqlite3VdbeFinalize(v);
  }
  sqlite3Error(db, rc, (zErr ? "%s" : 0), zErr);
  sqlite3DbFree(db, zErr);
  sqlite3StackFree(db, pParse);
  rc = sqlite3ApiExit(db, rc);
  sqlite3_mutex_leave(db->mutex);
  return rc;

  sqlite3_mutex_enter(db->mutex);
  v = (Vdbe*)p->pStmt;

  if( n<0 || iOffset<0 || (iOffset+n)>p->nByte ){
    /* Request is out of range. Return a transient error. */
    rc = SQLITE_ERROR;
    sqlite3Error(db, SQLITE_ERROR, 0);
  } else if( v==0 ){
  }else if( v==0 ){
    /* If there is no statement handle, then the blob-handle has
    ** already been invalidated. Return SQLITE_ABORT in this case.
    */
    rc = SQLITE_ABORT;
  }else{
    /* Call either BtreeData() or BtreePutData(). If SQLITE_ABORT is
    ** returned, clean-up the statement handle.

** The Incrblob.nByte field is fixed for the lifetime of the Incrblob
** so no mutex is required for access.
*/
int sqlite3_blob_bytes(sqlite3_blob *pBlob){
  Incrblob *p = (Incrblob *)pBlob;
  return p ? p->nByte : 0;
}

/*
** Move an existing blob handle to point to a different row of the same
** database table.
**
** If an error occurs, or if the specified row does not exist or does not
** contain a blob or text value, then an error code is returned and the
** database handle error code and message set. If this happens, then all 
** subsequent calls to sqlite3_blob_xxx() functions (except blob_close()) 
** immediately return SQLITE_ABORT.
*/
int sqlite3_blob_reopen(sqlite3_blob *pBlob, sqlite3_int64 iRow){
  int rc;
  Incrblob *p = (Incrblob *)pBlob;
  sqlite3 *db;

  if( p==0 ) return SQLITE_MISUSE_BKPT;
  db = p->db;
  sqlite3_mutex_enter(db->mutex);

  if( p->pStmt==0 ){
    /* If there is no statement handle, then the blob-handle has
    ** already been invalidated. Return SQLITE_ABORT in this case.
    */
    rc = SQLITE_ABORT;
  }else{
    char *zErr;
    rc = blobSeekToRow(p, iRow, &zErr);
    if( rc!=SQLITE_OK ){
      sqlite3Error(db, rc, (zErr ? "%s" : 0), zErr);
      sqlite3DbFree(db, zErr);
    }
    assert( rc!=SQLITE_SCHEMA );
  }

  rc = sqlite3ApiExit(db, rc);
  sqlite3_mutex_leave(db->mutex);
  return rc;
}

#endif /* #ifndef SQLITE_OMIT_INCRBLOB */

# 2006 October 31 (scaaarey)
# 2006 October 31 
#
# The author disclaims copyright to this source code.
# The author disclaims copyright to this source code.  In place of
# a legal notice, here is a blessing:
#
#    May you do good and not evil.
#    May you find forgiveness for yourself and forgive others.
#    May you share freely, never taking more than you give.
#
#*************************************************************************
# This file implements regression tests for SQLite library.  The focus
# here is testing correct handling of excessively long terms.
# here is testing correct handling of very long terms.
#
# $Id: fts3ah.test,v 1.1 2007/08/20 17:38:42 shess Exp $
#

set testdir [file dirname $argv0]
source $testdir/tester.tcl

# If SQLITE_ENABLE_FTS3 is defined, omit this file.
# If SQLITE_ENABLE_FTS3 is not defined, omit this file.
ifcapable !fts3 {
  finish_test
  return
}

# Generate a term of len copies of char.
proc bigterm {char len} {
  for {set term ""} {$len>0} {incr len -1} {
    append term $char
  }
  return $term
}

# Generate a document of bigterms based on characters from the list
# chars.
proc bigtermdoc {chars len} {
  set doc ""
  foreach char $chars {
    append doc " " [bigterm $char $len]
    append doc " " [string repeat $char $len]
  }
  return $doc
}

set len 5000
set doc1 [bigtermdoc {a b c d} $len]
set doc2 [bigtermdoc {b d e f} $len]
set doc3 [bigtermdoc {a c e} $len]

set aterm [bigterm a $len]
set bterm [bigterm b $len]
set xterm [bigterm x $len]
set aterm [string repeat a $len]
set bterm [string repeat b $len]
set xterm [string repeat x $len]

db eval {
  CREATE VIRTUAL TABLE t1 USING fts3(content);
  INSERT INTO t1 (rowid, content) VALUES(1, $doc1);
  INSERT INTO t1 (rowid, content) VALUES(2, $doc2);
  INSERT INTO t1 (rowid, content) VALUES(3, $doc3);
}

# No hits at all.  Returns empty doclists from termSelect().
do_test fts3ah-1.1 {
  execsql {SELECT rowid FROM t1 WHERE t1 MATCH 'something'}
} {}

do_test fts3ah-1.2 {
  execsql {SELECT rowid FROM t1 WHERE t1 MATCH $aterm}
} {1 3}

do_test fts3ah-1.2 {
do_test fts3ah-1.3 {
  execsql {SELECT rowid FROM t1 WHERE t1 MATCH $xterm}
} {}

do_test fts3ah-1.3 {
do_test fts3ah-1.4 {
  execsql "SELECT rowid FROM t1 WHERE t1 MATCH '$aterm -$xterm'"
} {1 3}

do_test fts3ah-1.4 {
do_test fts3ah-1.5 {
  execsql "SELECT rowid FROM t1 WHERE t1 MATCH '\"$aterm $bterm\"'"
} {1}

finish_test

source $testdir/tester.tcl

# If SQLITE_ENABLE_FTS3 is not defined, omit this file.
ifcapable !fts3 {
  finish_test
  return
}

set ::testprefix fts3ao

#---------------------------------------------------------------------
# These tests, fts3ao-1.*, test that ticket #2429 is fixed.
#
db eval {
  CREATE VIRTUAL TABLE t1 USING fts3(a, b, c);
  INSERT INTO t1(a, b, c) VALUES('one three four', 'one four', 'one four two');

      INSERT INTO t5 VALUES('Down came a jumbuck to drink at that billabong');
      ALTER TABLE t5 RENAME TO t6;
      INSERT INTO t6 VALUES('Down came the troopers, one, two, three');
    ROLLBACK;
    SELECT * FROM t5;
  }
} {{the quick brown fox} {jumped over the} {lazy dog}}

# Test that it is possible to rename an FTS4 table. Renaming an FTS4 table
# involves renaming the extra %_docsize and %_stat tables.
#
do_execsql_test 5.1 {
  CREATE VIRTUAL TABLE t7 USING FTS4;
  INSERT INTO t7 VALUES('coined by a German clinician');
  SELECT count(*) FROM sqlite_master WHERE name LIKE 't7%';
  SELECT count(*) FROM sqlite_master WHERE name LIKE 't8%';
} {6 0}
do_execsql_test 5.2 {
  ALTER TABLE t7 RENAME TO t8;
  SELECT count(*) FROM sqlite_master WHERE name LIKE 't7%';
  SELECT count(*) FROM sqlite_master WHERE name LIKE 't8%';
} {0 6}

finish_test

# 2010 October 27
#
#    May you do good and not evil.
#    May you find forgiveness for yourself and forgive others.
#    May you share freely, never taking more than you give.
#
#***********************************************************************
# Test that the FTS3 extension does not crash when it encounters a
# corrupt data structure on disk.
#


set testdir [file dirname $argv0]
source $testdir/tester.tcl

# If SQLITE_ENABLE_FTS3 is not defined, omit this file.
ifcapable !fts3 { finish_test ; return }

set ::testprefix fts3corrupt

do_execsql_test 1.0 {
  CREATE VIRTUAL TABLE t1 USING fts3;
  INSERT INTO t1 VALUES('hello');
} {}

do_test fts3corrupt-1.1 {
  set blob [db one {SELECT root from t1_segdir}]
  set blob [binary format a7ca* $blob 24 [string range $blob 8 end]]
  execsql { UPDATE t1_segdir SET root = $blob }
} {}

do_test fts3corrupt-1.2 {
  foreach w {a b c d e f g h i j k l m n o} {
    execsql { INSERT INTO t1 VALUES($w) }
  }
} {}

do_catchsql_test 1.3 {
  INSERT INTO t1 VALUES('world');
} {1 {database disk image is malformed}}

finish_test

# 2009 December 03
#
#    May you do good and not evil.
#    May you find forgiveness for yourself and forgive others.
#    May you share freely, never taking more than you give.
#
#***********************************************************************
#
# The tests in this file are structural coverage tests. They are designed
# The tests in this file are structural coverage tests for FTS3.
# to complement the tests in fts3rnd.test and fts3doc.test. Between them,
# the three files should provide full coverage of the fts3 extension code.
#

set testdir [file dirname $argv0]
source $testdir/tester.tcl

# If this build does not include FTS3, skip the tests in this file.
#
ifcapable !fts3 { finish_test ; return }
source $testdir/fts3_common.tcl
source $testdir/malloc_common.tcl

set DO_MALLOC_TEST 0
set testprefix fts3cov

#--------------------------------------------------------------------------
# When it first needs to read a block from the %_segments table, the FTS3 
# module compiles an SQL statement for that purpose. The statement is 
# stored and reused each subsequent time a block is read. This test case 
# tests the effects of an OOM error occuring while compiling the statement.
#

      INSERT INTO t1 VALUES('What makes her in the wood so late,');
      INSERT INTO t1 VALUES('A furlong from the castle gate?');
      INSERT INTO t1 VALUES('She had dreams all yesternight');
      INSERT INTO t1 VALUES('Of her own betrothed knight;');
      INSERT INTO t1 VALUES('And she in the midnight wood will pray');
      INSERT INTO t1 VALUES('For the weal of her lover that''s far away.');
    COMMIT;

  }
  execsql {
    INSERT INTO t1(t1) VALUES('optimize');
    SELECT substr(hex(root), 1, 2) FROM t1_segdir;
  }
} {03}

# Test the "missing entry" case:
do_test fts3cov-2.1 {
do_test fts3cov-2.2 {
  set root [db one {SELECT root FROM t1_segdir}]
  read_fts3varint [string range $root 1 end] left_child
  execsql { DELETE FROM t1_segments WHERE blockid = $left_child }
} {}
do_error_test fts3cov-2.2 {
do_error_test fts3cov-2.3 {
  SELECT * FROM t1 WHERE t1 MATCH 'c*'
} {database disk image is malformed}
} {SQL logic error or missing database}

# Test the "replaced with NULL" case:
do_test fts3cov-2.3 {
do_test fts3cov-2.4 {
  execsql { INSERT INTO t1_segments VALUES($left_child, NULL) }
} {}
do_error_test fts3cov-2.4 {
do_error_test fts3cov-2.5 {
  SELECT * FROM t1 WHERE t1 MATCH 'cloud'
} {database disk image is malformed}
} {SQL logic error or missing database}

#--------------------------------------------------------------------------
# The following tests are to test the effects of OOM errors while storing
# terms in the pending-hash table. Specifically, while creating doclist
# blobs to store in the table. More specifically, to test OOM errors while
# appending column numbers to doclists. For example, if a doclist consists
# of:

  INSERT INTO t13 VALUES('scalar two functions');
  INSERT INTO t13 VALUES('functions scalar two');
} -sqlbody {
  SELECT snippet(t13, '%%', '%%', '#') FROM t13 WHERE t13 MATCH 'two';
  SELECT snippet(t13, '%%', '%%') FROM t13 WHERE t13 MATCH 'two';
  SELECT snippet(t13, '%%') FROM t13 WHERE t13 MATCH 'two';
}

do_execsql_test 14.0 {
  CREATE VIRTUAL TABLE t14 USING fts4(a, b);
  INSERT INTO t14 VALUES('one two three', 'one three four');
  INSERT INTO t14 VALUES('a b c', 'd e a');
}
do_execsql_test 14.1 {
  SELECT rowid FROM t14 WHERE t14 MATCH '"one two three"'
} {1}
do_execsql_test 14.2 {
  SELECT rowid FROM t14 WHERE t14 MATCH '"one four"'
} {}
do_execsql_test 14.3 {
  SELECT rowid FROM t14 WHERE t14 MATCH '"e a"'
} {2}
do_execsql_test 14.5 {
  SELECT rowid FROM t14 WHERE t14 MATCH '"e b"'
} {}
do_catchsql_test 14.6 {
  SELECT rowid FROM t14 WHERE rowid MATCH 'one'
} {1 {unable to use function MATCH in the requested context}}
do_catchsql_test 14.7 {
  SELECT rowid FROM t14 WHERE docid MATCH 'one'
} {1 {unable to use function MATCH in the requested context}}

do_execsql_test 15.0 {
  CREATE VIRTUAL TABLE t15 USING fts4(a, b, c);
  INSERT INTO t15 VALUES('abc def ghi', 'abc2 def2 ghi2', 'abc3 def3 ghi3');
  INSERT INTO t15 VALUES('abc2 def2 ghi2', 'abc2 def2 ghi2', 'abc def3 ghi3');
}
do_execsql_test 15.1 {
  SELECT rowid FROM t15 WHERE t15 MATCH '"abc* def2"'
} {1 2}

# Test a corruption case.
#
do_execsql_test 16.1 {
  CREATE VIRTUAL TABLE t16 USING fts4;
  INSERT INTO t16 VALUES('theoretical work to examine the relationship');
  INSERT INTO t16 VALUES('solution of our problems on the invisible');
  DELETE FROM t16_content WHERE rowid = 2;
}
do_catchsql_test 16.2 {
  SELECT * FROM t16 WHERE t16 MATCH 'invisible'
} {1 {database disk image is malformed}}

# And another corruption test case.
#
do_execsql_test 17.1 {
  CREATE VIRTUAL TABLE t17 USING fts4;
  INSERT INTO t17(content) VALUES('one one one');
  UPDATE t17_segdir SET root = X'00036F6E65FFFFFFFFFFFFFFFFFFFFFF02030300'
} {}
do_catchsql_test 17.2 {
  SELECT * FROM t17 WHERE t17 MATCH 'one'
} {1 {database disk image is malformed}}




finish_test

# 2010 October 15
#
# The author disclaims copyright to this source code.  In place of
# a legal notice, here is a blessing:
#
#    May you do good and not evil.
#    May you find forgiveness for yourself and forgive others.
#    May you share freely, never taking more than you give.
#
#***********************************************************************

set testdir [file dirname $argv0]
source $testdir/tester.tcl
source $testdir/malloc_common.tcl

ifcapable !fts3 {
  finish_test
  return
}

set sqlite_fts3_enable_parentheses 1

set ::testprefix fts3defer

#--------------------------------------------------------------------------
# Test cases fts3defer-1.* are the "warm body" cases. The database contains
# one row with 15000 instances of the token "a". This makes the doclist for
# "a" so large that FTS3 will avoid loading it in most cases.
#
# To show this, test cases fts3defer-1.2.* execute a bunch of FTS3 queries
# involving token "a". Then, fts3defer-1.3.* replaces the doclist for token
# "a" with all zeroes and fts3defer-1.4.* repeats the tests from 1.2. If
# the tests still work, we can conclude that the doclist for "a" was not
# used.
# 

set aaa [string repeat "a " 15000]

do_execsql_test 1.1 {
  CREATE VIRTUAL TABLE t1 USING fts4;
  BEGIN;
    INSERT INTO t1 VALUES('this is a dog');
    INSERT INTO t1 VALUES('an instance of a phrase');
    INSERT INTO t1 VALUES('an instance of a longer phrase');
    INSERT INTO t1 VALUES($aaa);
  COMMIT;
} {}

set tests {
  1  {SELECT rowid FROM t1 WHERE t1 MATCH '"a dog"'}                 {1}
  2  {SELECT rowid FROM t1 WHERE t1 MATCH '"is a dog"'}              {1}
  3  {SELECT rowid FROM t1 WHERE t1 MATCH '"a longer phrase"'}       {3}
  4  {SELECT snippet(t1) FROM t1 WHERE t1 MATCH '"a longer phrase"'}  
     {"an instance of <b>a</b> <b>longer</b> <b>phrase</b>"}
  5  {SELECT rowid FROM t1 WHERE t1 MATCH 'a dog'}                   {1}
}

do_select_tests 1.2 $tests

do_execsql_test 1.3 {
  SELECT count(*) FROM t1_segments WHERE length(block)>10000;
  UPDATE t1_segments 
    SET block = zeroblob(length(block)) 
    WHERE length(block)>10000;
} {1}

do_select_tests 1.4 $tests

# Drop the table. It is corrupt now anyhow, so not useful for subsequent tests.
#
do_execsql_test 1.5 { DROP TABLE t1 }

#--------------------------------------------------------------------------
# These tests - fts3defer-2.* - are more rigorous. They test that for a
# variety of queries, FTS3 and FTS4 return the same results. And that 
# zeroing the very large doclists that FTS4 does not load does not change
# the results.
#
# They use the following pseudo-randomly generated document data. The
# tokens "zm" and "jk" are especially common in this dataset. Additionally,
# two documents are added to the pseudo-random data before it is loaded
# into FTS4 containing 100,000 instances of the "zm" and "jk" tokens. This
# makes the doclists for those tokens so large that FTS4 avoids loading them
# into memory if possible.
#
set data [list]
lappend data [string repeat "zm " 100000]
lappend data [string repeat "jk " 100000]
lappend data {*}{
  "zm zm agmckuiu uhzq nsab jk rrkx duszemmzl hyq jk"
  "jk uhzq zm zm rgpzmlnmd zm zk jk jk zm"
  "duszemmzl zm jk xldlpy zm jk sbptoa xh jk xldlpy"
  "zm xh zm xqf azavwm jk jk trqd rgpzmlnmd jk"
  "zm vwq urvysbnykk ubwrfqnbjf zk lsz jk doiwavhwwo jk jk"
  "jk xduvfhk orpfawpx zkhdvkw jk mjpavjuhw zm jk duszemmzl zm"
  "jk igju jk jk zm hmjf xh zm gwdfhwurx zk"
  "vgsld jk jk zm hrlipdm jn zm zsmhnf vgsld duszemmzl"
  "gtuiexzsu aayxpmve zm zm zm drir scpgna xh azavwm uhzq"
  "farlehdhq hkfoudzftq igju duszemmzl xnxhf ewle zm hrlipdm urvysbnykk kn"
  "xnxhf jk jk agmckuiu duszemmzl jk zm zm jk vgsld"
  "zm zm zm jk jk urvysbnykk ogttbykvt zm zm jk"
  "iasrqgqv zm azavwm zidhxhbtv jk jk mjpavjuhw zm zm ajmvcydy"
  "rgpzmlnmd tmt mjpavjuhw xh igju jk azavwm fibokdry vgsld ofm"
  "zm jk vgsld jk xh jk csjqxhgj drir jk pmrb"
  "xh jk jk zm rrkx duszemmzl mjpavjuhw xldlpy igju zm"
  "jk hkfoudzftq zf rrkx wdmy jupk jk zm urvysbnykk npywgdvgz"
  "zm jk zm zm zhbrzadb uenvbm aayxpmve urvysbnykk duszemmzl jk"
  "uenvbm jk zm fxw xh bdilwmjw mjpavjuhw uv jk zm"
  "nk jk bnhc pahlds jk igju dzadnqzprr jk jk jk"
  "uhzq uv zm duszemmzl tlqix jk jk xh jk zm"
  "jk zm agmckuiu urvysbnykk jk jk zm zm jk jk"
  "azavwm mjpavjuhw lsgshn trqd xldlpy ogyavjvv agmckuiu ryvwwhlbc jk jk"
  "tmt jk zk zm azavwm ofm acpgim bvgimjik iasrqgqv wuvajhwqz"
  "igju ogyavjvv xrbdak rrkx fibokdry zf ujfhmrllq jk zm hxgwvib"
  "zm pahlds jk uenvbm aayxpmve iaf hmjf xph vnlyvtkgx zm"
  "jk xnxhf igju jk xh jk nvfasfh zm js jk"
  "zm zm rwaj igju xr rrkx xnxhf nvfasfh skxbsqzvmt xatbxeqq"
  "vgsld zm ujfhmrllq uhzq ogyavjvv nsab azavwm zm vgsld jmfiqhwnjg"
  "ymjoym duszemmzl urvysbnykk azavwm jk jmfiqhwnjg bu qcdziqomqk vnlyvtkgx"
  "zm nbilqcnz dzadnqzprr xh bkfgzsxn urvysbnykk xrujfzxqf zm zf agmckuiu"
  "jk urvysbnykk nvfasfh zf xh zm zm qcdziqomqk qvxtclg wdmy"
  "fibokdry jk urvysbnykk jk xr osff zm cvnnsl zm vgsld"
  "jk mjpavjuhw hkfoudzftq jk zm xh xqf urvysbnykk jk iasrqgqv"
  "jk csjqxhgj duszemmzl iasrqgqv aayxpmve zm brsuoqww jk qpmhtvl wluvgsw"
  "jk mj azavwm jk zm jn dzadnqzprr zm jk uhzq"
  "zk xqf jupk fxw nbilqcnz zm jk jcpiwj tznlvbfcv nvfasfh"
  "jk jcpiwj zm xnxhf zm mjpavjuhw mj drir pa pvjrjlas"
  "duszemmzl dzadnqzprr jk swc duszemmzl tmt jk jk pahlds jk"
  "zk zm jk zm zm eczkjblu zm hi pmrb jk"
  "azavwm zm iz agmckuiu jk sntk jk duszemmzl duszemmzl zm"
  "jk zm jk eczkjblu urvysbnykk sk gnl jk ttvgf hmjf"
  "jk bnhc jjrxpjkb mjpavjuhw fibokdry igju jk zm zm xh"
  "wxe ogttbykvt uhzq xr iaf zf urvysbnykk aayxpmve oacaxgjoo mjpavjuhw"
  "gazrt jk ephknonq myjp uenvbm wuvajhwqz jk zm xnxhf nvfasfh"
  "zm aayxpmve csjqxhgj xnxhf xr jk aayxpmve xnxhf zm zm"
  "sokcyf zm ogyavjvv jk zm fibokdry zm jk igju igju"
  "vgsld bvgimjik xuprtlyle jk akmikrqyt jk aayxpmve hkfoudzftq ddjj ithtir"
  "zm uhzq ovkyevlgv zk uenvbm csjqxhgj jk vgsld pgybs jk"
  "zm agmckuiu zexh fibokdry jk uhzq bu tugflixoex xnxhf sk"
  "zm zf uenvbm jk azavwm zm zm agmckuiu zm jk"
  "rrkx jk zf jt zm oacaxgjoo fibokdry wdmy igju csjqxhgj"
  "hi igju zm jk zidhxhbtv dzadnqzprr jk jk trqd duszemmzl"
  "zm zm mjpavjuhw xrbdak qrvbjruc jk qzzqdxq guwq cvnnsl zm"
  "ithtir jk jk qcdziqomqk zm farlehdhq zm zm xrbdak jk"
  "ixfipk csjqxhgj azavwm sokcyf ttvgf vgsld jk sk xh zk"
  "nvfasfh azavwm zm zm zm fxw nvfasfh zk gnl trqd"
  "zm fibokdry csjqxhgj ofm dzadnqzprr jk akmikrqyt orpfawpx duszemmzl vwq"
  "csjqxhgj jk jk vgsld urvysbnykk jk nxum jk jk nxum"
  "zm hkfoudzftq jk ryvwwhlbc mjpavjuhw ephknonq jk zm ogyavjvv zm"
  "lwa hi xnxhf qdyerbws zk njtc jk uhzq zm jk"
  "trqd zm dzadnqzprr zm urvysbnykk jk lsz jk mjpavjuhw cmnnkna"
  "duszemmzl zk jk jk fibokdry jseuhjnzo zm aayxpmve zk jk"
  "fibokdry jk sviq qvxtclg wdmy jk doiwavhwwo zexh jk zm"
  "jupk zm xh jk mjpavjuhw zm jk nsab npywgdvgz duszemmzl"
  "zm igju zm zm nvfasfh eh hkfoudzftq fibokdry fxw xkblf"
  "jk zm jk jk zm xh zk abthnzcv zf csjqxhgj"
  "zm zm jk nkaotm urvysbnykk sbptoa bq jk ktxdty ubwrfqnbjf"
  "nvfasfh aayxpmve xdcuz zm tugflixoex jcpiwj zm mjpavjuhw fibokdry doiwavhwwo"
  "iaf jk mjpavjuhw zm duszemmzl jk jk uhzq pahlds fibokdry"
  "ddjj zk azavwm jk swc zm gjtexkv jk xh jk"
  "igju jk csjqxhgj zm jk dzadnqzprr duszemmzl ulvcbv jk jk"
  "jk fibokdry zm csjqxhgj jn zm zm zm zf uhzq"
  "duszemmzl jk xkblf zk hrlipdm aayxpmve uenvbm uhzq jk zf"
  "dzadnqzprr jk zm zdu nvfasfh zm jk urvysbnykk hmjf jk"
  "jk aayxpmve aserrdxm acpgim fibokdry jk drir wxe brsuoqww rrkx"
  "uhzq csjqxhgj nvfasfh jk rrkx qbamok trqd uenvbm sntk zm"
  "ps azavwm zkhdvkw jk zm jk jk zm csjqxhgj xedlrcfo"
  "jk jk ogyavjvv jk zm farlehdhq duszemmzl jk agitgxamxe jk"
  "qzzqdxq rwaj jk jk zm xqf jk uenvbm jk zk"
  "zm hxgwvib akmikrqyt zf agmckuiu uenvbm bq npywgdvgz azavwm jk"
  "zf jmfiqhwnjg js igju zm aayxpmve zm mbxnljomiv csjqxhgj nvfasfh"
  "zm jk jk gazrt jk jk lkc jk nvfasfh jk"
  "xldlpy orpfawpx zkhdvkw jk zm igju zm urvysbnykk dzadnqzprr mbxnljomiv"
  "urvysbnykk jk zk igju zm uenvbm jk zm ithtir jk"
  "zm zk zm zf ofm zm xdcuz dzadnqzprr zm vgsld"
  "sbptoa jk tugflixoex jk zm zm vgsld zm xh zm"
  "uhzq jk zk evvivo vgsld vniqnuynvf agmckuiu jk zm zm"
  "zm nvfasfh zm zm zm abthnzcv uenvbm jk zk dzadnqzprr"
  "zm azavwm igju qzzqdxq jk xnxhf abthnzcv jk nvfasfh zm"
  "qbamok fxw vgsld igju cmnnkna xnxhf vniqnuynvf zk xh zm"
  "nvfasfh zk zm mjpavjuhw dzadnqzprr jk jk duszemmzl xldlpy nvfasfh"
  "xnxhf sviq nsab npywgdvgz osff vgsld farlehdhq fibokdry wjbkhzsa hhac"
  "zm azavwm scpgna jk jk bq jk duszemmzl fibokdry ovkyevlgv"
  "csjqxhgj zm jk jk duszemmzl zk xh zm jk zf"
  "urvysbnykk dzadnqzprr csjqxhgj mjpavjuhw ubwrfqnbjf nkaotm jk jk zm drir"
  "nvfasfh xh igju zm wluvgsw jk zm srwwnezqk ewle ovnq"
  "jk nvfasfh eh ktxdty urvysbnykk vgsld zm jk eh uenvbm"
  "orpfawpx pahlds jk uhzq hi zm zm zf jk dzadnqzprr"
  "srwwnezqk csjqxhgj rbwzuf nvfasfh jcpiwj xldlpy nvfasfh jk vgsld wjybxmieki"
}

proc add_empty_records {n} {
  execsql BEGIN
  for {set i 0} {$i < $n} {incr i} {
    execsql { INSERT INTO t1 VALUES('') }
  }
  execsql COMMIT
}


#set e [list]
#foreach d $data {set e [concat $e $d]}
#puts [lsort -unique $e]
#exit

set zero_long_doclists {
  UPDATE t1_segments SET block=zeroblob(length(block)) WHERE length(block)>10000
}

foreach {tn setup} {
  1 {
    set dmt_modes 0
    execsql { CREATE VIRTUAL TABLE t1 USING FTS3 }
    foreach doc $data { execsql { INSERT INTO t1 VALUES($doc) } }
  }
  2 {
    set dmt_modes 0
    execsql { CREATE VIRTUAL TABLE t1 USING FTS4 }
    foreach doc $data { execsql { INSERT INTO t1 VALUES($doc) } }
  }
  3 {
    set dmt_modes {0 1 2}
    execsql { CREATE VIRTUAL TABLE t1 USING FTS4 }
    foreach doc $data { execsql { INSERT INTO t1 VALUES($doc) } }
    add_empty_records 1000
    execsql $zero_long_doclists
  }
  4 {
    set dmt_modes 0
    execsql { CREATE VIRTUAL TABLE t1 USING FTS4 }
    foreach doc $data { execsql { INSERT INTO t1 VALUES($doc) } }
    add_empty_records 1000
    execsql "INSERT INTO t1(t1) VALUES('optimize')"
    execsql $zero_long_doclists
  }
} {

  execsql { DROP TABLE IF EXISTS t1 }
  eval $setup
  set ::testprefix fts3defer-2.$tn
  set DO_MALLOC_TEST 0

  do_execsql_test 0 { 
    SELECT count(*) FROM t1_segments WHERE length(block)>10000 
  } {2}

  do_select_test 1.1 {
    SELECT rowid FROM t1 WHERE t1 MATCH 'jk xnxhf'
  } {13 29 40 47 48 52 63 92}
  do_select_test 1.2 {
    SELECT rowid FROM t1 WHERE t1 MATCH 'jk eh'
  } {100}
if {$tn==3} breakpoint
  do_select_test 1.3 {
    SELECT rowid FROM t1 WHERE t1 MATCH 'jk ubwrfqnbjf'
  } {7 70 98}
  do_select_test 1.4 {
    SELECT rowid FROM t1 WHERE t1 MATCH 'duszemmzl jk'
  } {3 5 8 10 13 18 20 23 32 37 41 43 55 60 65 67 72 74 76 81 94 96 97}
  do_select_test 1.5 {
    SELECT rowid FROM t1 WHERE t1 MATCH 'ubwrfqnbjf jk'
  } {7 70 98}
  do_select_test 1.6 {
    SELECT rowid FROM t1 WHERE t1 MATCH 'jk ubwrfqnbjf jk jk jk jk'
  } {7 70 98}
  do_select_test 1.7 {
    SELECT rowid FROM t1 WHERE t1 MATCH 'zm xnxhf'
  } {12 13 29 30 40 47 48 52 63 92 93}
  do_select_test 1.8 {
    SELECT rowid FROM t1 WHERE t1 MATCH 'zm eh'
  } {68 100}
  do_select_test 1.9 {
    SELECT rowid FROM t1 WHERE t1 MATCH 'zm ubwrfqnbjf'
  } {7 70 98}
  do_select_test 1.10 {
    SELECT rowid FROM t1 WHERE t1 MATCH 'z* vgsld'
  } {10 13 17 31 35 51 58 88 89 90 93 100}
  do_select_test 1.11 {
    SELECT rowid FROM t1 
    WHERE t1 MATCH '(
      zdu OR zexh OR zf OR zhbrzadb OR zidhxhbtv OR 
      zk OR zkhdvkw OR zm OR zsmhnf
    ) vgsld'
  } {10 13 17 31 35 51 58 88 89 90 93 100}

  do_select_test 2.1 {
    SELECT rowid FROM t1 WHERE t1 MATCH '"zm agmckuiu"'
  } {3 24 52 53}
  do_select_test 2.2 {
    SELECT rowid FROM t1 WHERE t1 MATCH '"zm zf"'
  } {33 53 75 88 101}
  do_select_test 2.3 {
    SELECT rowid FROM t1 WHERE t1 MATCH '"zm aayxpmve"'
  } {48 65 84}
  do_select_test 2.4 {
    SELECT rowid FROM t1 WHERE t1 MATCH '"aayxpmve zm"'
  } {11 37 84}
  do_select_test 2.5 {
    SELECT rowid FROM t1 WHERE t1 MATCH '"jk azavwm"'
  } {16 53}
  do_select_test 2.6 {
    SELECT rowid FROM t1 WHERE t1 MATCH '"xh jk jk"'
  } {18}
  do_select_test 2.7 {
    SELECT rowid FROM t1 WHERE t1 MATCH '"zm jk vgsld"'
  } {13 17}
  do_select_test 2.8 {
    SELECT rowid FROM t1 WHERE t1 MATCH '"zm jk vgsld lkjlkjlkj"'
  } {}

  do_select_test 3.1 {
    SELECT snippet(t1, '[', ']') FROM t1 WHERE t1 MATCH '"zm agmckuiu"'
  } {
    {zm [zm] [agmckuiu] uhzq nsab jk rrkx duszemmzl hyq jk} 
    {jk [zm] [agmckuiu] urvysbnykk jk jk zm zm jk jk} 
    {[zm] [agmckuiu] zexh fibokdry jk uhzq bu tugflixoex xnxhf sk} 
    {zm zf uenvbm jk azavwm zm [zm] [agmckuiu] zm jk}
  }

  do_select_test 3.2 {
    SELECT snippet(t1, '[', ']') FROM t1 WHERE t1 MATCH 'xnxhf jk'
  } {
    {[xnxhf] [jk] [jk] agmckuiu duszemmzl [jk] zm zm [jk] vgsld} 
    {[jk] [xnxhf] igju [jk] xh [jk] nvfasfh zm js [jk]} 
    {[jk] jcpiwj zm [xnxhf] zm mjpavjuhw mj drir pa pvjrjlas} 
    {gazrt [jk] ephknonq myjp uenvbm wuvajhwqz [jk] zm [xnxhf] nvfasfh} 
    {zm aayxpmve csjqxhgj [xnxhf] xr [jk] aayxpmve [xnxhf] zm zm} 
    {zm agmckuiu zexh fibokdry [jk] uhzq bu tugflixoex [xnxhf] sk} 
    {lwa hi [xnxhf] qdyerbws zk njtc [jk] uhzq zm [jk]} 
    {zm azavwm igju qzzqdxq [jk] [xnxhf] abthnzcv [jk] nvfasfh zm}
  }

  do_select_test 4.1 {
    SELECT offsets(t1) FROM t1 WHERE t1 MATCH '"jk uenvbm"'
  } {
    {0 0 10 2 0 1 13 6} {0 0 26 2 0 1 29 6}
  }

  do_select_test 4.2 {
    SELECT offsets(t1) FROM t1 WHERE t1 MATCH 'duszemmzl jk fibokdry'
  } {
    {0 2 3 8 0 1 36 2 0 0 58 9} 
    {0 0 0 9 0 1 13 2 0 1 16 2 0 2 19 8 0 1 53 2} 
    {0 1 4 2 0 0 20 9 0 1 30 2 0 1 33 2 0 2 48 8} 
    {0 1 17 2 0 1 20 2 0 1 26 2 0 0 29 9 0 2 39 8}
  }

  do_select_test 4.3 {
    SELECT offsets(t1) FROM t1 
    WHERE t1 MATCH 'vgsld (hrlipdm OR (aapmve NEAR duszemmzl))'
  } {{0 0 0 5 0 1 15 7 0 0 36 5}}

  # The following block of tests runs normally with FTS3 or FTS4 without the
  # long doclists zeroed. And with OOM-injection for FTS4 with long doclists
  # zeroed. Change this by messing with the [set dmt_modes] commands above.
  #
  foreach DO_MALLOC_TEST $dmt_modes {
    
    # Phrase search.
    do_select_test 5.$DO_MALLOC_TEST.1 {
      SELECT rowid FROM t1 WHERE t1 MATCH '"jk mjpavjuhw"'
    } {8 15 36 64 67 72}

    # Multiple tokens search.
    do_select_test 5.$DO_MALLOC_TEST.2 {
      SELECT rowid FROM t1 WHERE t1 MATCH 'duszemmzl zm'
    } {3 5 8 10 12 13 18 20 23 37 43 55 60 65 67 72 74 81 94 96 97}

    # snippet() function with phrase.
    do_select_test 5.$DO_MALLOC_TEST.3 {
      SELECT snippet(t1, '[', ']') FROM t1 WHERE t1 MATCH '"zm aayxpmve"'
    } {
      {[zm] [aayxpmve] csjqxhgj xnxhf xr jk aayxpmve xnxhf zm zm} 
      {duszemmzl zk jk jk fibokdry jseuhjnzo [zm] [aayxpmve] zk jk} 
      {zf jmfiqhwnjg js igju [zm] [aayxpmve] zm mbxnljomiv csjqxhgj nvfasfh}
    }
    
    # snippet() function with multiple tokens.
    do_select_test 5.$DO_MALLOC_TEST.4 {
      SELECT snippet(t1, '[', ']') FROM t1 WHERE t1 MATCH 'zm zhbrzadb'
    } {
      {[zm] jk [zm] [zm] [zhbrzadb] uenvbm aayxpmve urvysbnykk duszemmzl jk}
    }
    
    # snippet() function with phrase.
    do_select_test 5.$DO_MALLOC_TEST.5 {
      SELECT offsets(t1) FROM t1 WHERE t1 MATCH '"zm aayxpmve"'
    } {
      {0 0 0 2 0 1 3 8} {0 0 38 2 0 1 41 8} {0 0 22 2 0 1 25 8}
    }
    
    # snippet() function with multiple tokens.
    do_select_test 5.$DO_MALLOC_TEST.6 {
      SELECT offsets(t1) FROM t1 WHERE t1 MATCH 'zm zhbrzadb'
    } {
      {0 0 0 2 0 0 6 2 0 0 9 2 0 1 12 8}
    }

    set DO_MALLOC_TEST 0
  }

  do_select_test 6.1 {
    SELECT rowid FROM t1 
    WHERE t1 MATCH 'vgsld (hrlipdm OR (aayxpmve duszemmzl))'
  } {10}
  do_select_test 6.2.1 {
    SELECT rowid FROM t1 WHERE t1 MATCH '"jk xduvfhk"'
  } {8}
  do_select_test 6.2.2 {
    SELECT rowid FROM t1 WHERE t1 MATCH '"zm azavwm"'
  } {15 26 92 96}
  do_select_test 6.2.3 {
    SELECT rowid FROM t1 WHERE t1 MATCH '"jk xduvfhk" OR "zm azavwm"'
  } {8 15 26 92 96}
}

set testprefix fts3defer

do_execsql_test 3.1 {
  CREATE VIRTUAL TABLE x1 USING fts4(a, b);
  INSERT INTO x1 VALUES('a b c', 'd e f');
  INSERT INTO x1 SELECT * FROM x1;
  INSERT INTO x1 SELECT * FROM x1;
  INSERT INTO x1 SELECT * FROM x1;
  INSERT INTO x1 SELECT * FROM x1;
}
do_execsql_test 3.2 "
  INSERT INTO x1 VALUES(
    '[string repeat {d } 3000]', '[string repeat {f } 30000]'
  );
  INSERT INTO x1(x1) VALUES('optimize');
"

do_execsql_test 3.3 {
  SELECT count(*) FROM x1 WHERE x1 MATCH '"d e f"'
} {16}


finish_test