SQLite

  if( rc!=SQLITE_OK ){
    sqlite3_result_error_code(pCtx, rc);
  }
}
/*
** End of highlight() implementation.
**************************************************************************/

/*
** Context object passed to the fts5SentenceFinderCb() function.
*/
typedef struct Fts5SFinder Fts5SFinder;
struct Fts5SFinder {
  int iPos;                       /* Current token position */
  int nFirstAlloc;                /* Allocated size of aFirst[] */
  int nFirst;                     /* Number of entries in aFirst[] */
  int *aFirst;                    /* Array of first token in each sentence */
  const char *zDoc;               /* Document being tokenized */
};

/*
** Add an entry to the Fts5SFinder.aFirst[] array. Grow the array if
** necessary. Return SQLITE_OK if successful, or SQLITE_NOMEM if an
** error occurs.
*/
static int fts5SentenceFinderAdd(Fts5SFinder *p, int iAdd){
  if( p->nFirstAlloc==p->nFirst ){
    int nNew = p->nFirstAlloc ? p->nFirstAlloc*2 : 64;
    int *aNew;

    aNew = (int*)sqlite3_realloc(p->aFirst, nNew*sizeof(int));
    if( aNew==0 ) return SQLITE_NOMEM;
    p->aFirst = aNew;
    p->nFirstAlloc = nNew;
  }
  p->aFirst[p->nFirst++] = iAdd;
  return SQLITE_OK;
}

/*
** This function is an xTokenize() callback used by the auxiliary snippet()
** function. Its job is to identify tokens that are the first in a sentence.
** For each such token, an entry is added to the SFinder.aFirst[] array.
*/
static int fts5SentenceFinderCb(
  void *pContext,                 /* Pointer to HighlightContext object */
  int tflags,                     /* Mask of FTS5_TOKEN_* flags */
  const char *pToken,             /* Buffer containing token */
  int nToken,                     /* Size of token in bytes */
  int iStartOff,                  /* Start offset of token */
  int iEndOff                     /* End offset of token */
){
  int rc = SQLITE_OK;

  if( (tflags & FTS5_TOKEN_COLOCATED)==0 ){
    Fts5SFinder *p = (Fts5SFinder*)pContext;
    if( p->iPos>0 ){
      int i;
      char c = 0;
      for(i=iStartOff-1; i>=0; i--){
        c = p->zDoc[i];
        if( c!=' ' && c!='\t' && c!='\n' && c!='\r' ) break;
      }
      if( i!=iStartOff-1 && (c=='.' || c==':') ){
        rc = fts5SentenceFinderAdd(p, p->iPos);
      }
    }else{
      rc = fts5SentenceFinderAdd(p, 0);
    }
    p->iPos++;
  }
  return rc;
}

static int fts5SnippetScore(
  const Fts5ExtensionApi *pApi,   /* API offered by current FTS version */
  Fts5Context *pFts,              /* First arg to pass to pApi functions */
  int nDocsize,                   /* Size of column in tokens */
  unsigned char *aSeen,           /* Array with one element per query phrase */
  int iCol,                       /* Column to score */
  int iPos,                       /* Starting offset to score */
  int nToken,                     /* Max tokens per snippet */
  int *pnScore,                   /* OUT: Score */
  int *piPos                      /* OUT: Adjusted offset */
){
  int rc;
  int i;
  int ip = 0;
  int ic = 0;
  int iOff = 0;
  int iFirst = -1;
  int nInst;
  int nScore = 0;
  int iLast = 0;

  rc = pApi->xInstCount(pFts, &nInst);
  for(i=0; i<nInst && rc==SQLITE_OK; i++){
    rc = pApi->xInst(pFts, i, &ip, &ic, &iOff);
    if( rc==SQLITE_OK && ic==iCol && iOff>=iPos && iOff<(iPos+nToken) ){
      nScore += (aSeen[ip] ? 1 : 1000);
      aSeen[ip] = 1;
      if( iFirst<0 ) iFirst = iOff;
      iLast = iOff + pApi->xPhraseSize(pFts, ip);
    }
  }

  *pnScore = nScore;
  if( piPos ){
    int iAdj = iFirst - (nToken - (iLast-iFirst)) / 2;
    if( (iAdj+nToken)>nDocsize ) iAdj = nDocsize - nToken;
    if( iAdj<0 ) iAdj = 0;
    *piPos = iAdj;
  }

  return rc;
}

/*
** Implementation of snippet() function.
*/
static void fts5SnippetFunction(
  const Fts5ExtensionApi *pApi,   /* API offered by current FTS version */
  Fts5Context *pFts,              /* First arg to pass to pApi functions */

  int nToken;                     /* 5th argument to snippet() */
  int nInst = 0;                  /* Number of instance matches this row */
  int i;                          /* Used to iterate through instances */
  int nPhrase;                    /* Number of phrases in query */
  unsigned char *aSeen;           /* Array of "seen instance" flags */
  int iBestCol;                   /* Column containing best snippet */
  int iBestStart = 0;             /* First token of best snippet */

  int nBestScore = 0;             /* Score of best snippet */
  int nColSize = 0;               /* Total size of iBestCol in tokens */
  Fts5SFinder sFinder;            /* Used to find the beginnings of sentences */
  int nCol;

  if( nVal!=5 ){
    const char *zErr = "wrong number of arguments to function snippet()";
    sqlite3_result_error(pCtx, zErr, -1);
    return;
  }

  nCol = pApi->xColumnCount(pFts);
  memset(&ctx, 0, sizeof(HighlightContext));
  iCol = sqlite3_value_int(apVal[0]);
  ctx.zOpen = (const char*)sqlite3_value_text(apVal[1]);
  ctx.zClose = (const char*)sqlite3_value_text(apVal[2]);
  zEllips = (const char*)sqlite3_value_text(apVal[3]);
  nToken = sqlite3_value_int(apVal[4]);


  iBestCol = (iCol>=0 ? iCol : 0);
  nPhrase = pApi->xPhraseCount(pFts);
  aSeen = sqlite3_malloc(nPhrase);
  if( aSeen==0 ){
    rc = SQLITE_NOMEM;
  }

  if( rc==SQLITE_OK ){
    rc = pApi->xInstCount(pFts, &nInst);
  }

  memset(&sFinder, 0, sizeof(Fts5SFinder));
  for(i=0; i<nCol; i++){
    if( iCol<0 || iCol==i ){
      int nDoc;
      int nDocsize;
      int ii;
      sFinder.iPos = 0;
      sFinder.nFirst = 0;
      rc = pApi->xColumnText(pFts, i, &sFinder.zDoc, &nDoc);
      if( rc!=SQLITE_OK ) break;
      rc = pApi->xTokenize(pFts, 
          sFinder.zDoc, nDoc, (void*)&sFinder,fts5SentenceFinderCb
      );
      if( rc!=SQLITE_OK ) break;
      rc = pApi->xColumnSize(pFts, i, &nDocsize);
      if( rc!=SQLITE_OK ) break;

      for(ii=0; rc==SQLITE_OK && ii<nInst; ii++){
        int ip, ic, io;
        int iAdj;
        int nScore;

        int jj;

        rc = pApi->xInst(pFts, ii, &ip, &ic, &io);
        if( ic!=i || rc!=SQLITE_OK ) continue;
        memset(aSeen, 0, nPhrase);
        rc = fts5SnippetScore(pApi, pFts, nDocsize, aSeen, i,
            io, nToken, &nScore, &iAdj

        );

        if( rc==SQLITE_OK && nScore>nBestScore ){
          nBestScore = nScore;
          iBestCol = i;
          iBestStart = iAdj;
          nColSize = nDocsize;
        }

        if( rc==SQLITE_OK && sFinder.nFirst && nDocsize>nToken ){
          for(jj=0; jj<(sFinder.nFirst-1); jj++){
            if( sFinder.aFirst[jj+1]>io ) break;
          }

          if( sFinder.aFirst[jj]<io ){
            int nScore;
            memset(aSeen, 0, nPhrase);
            rc = fts5SnippetScore(pApi, pFts, nDocsize, aSeen, i, 
              sFinder.aFirst[jj], nToken, &nScore, 0
            );

            nScore += (sFinder.aFirst[jj]==0 ? 120 : 100);
            if( rc==SQLITE_OK && nScore>nBestScore ){
              nBestScore = nScore;
              iBestCol = i;
              iBestStart = sFinder.aFirst[jj];

              nColSize = nDocsize;
            }
          }
        }
      }
    }
  }

  if( rc==SQLITE_OK ){
    rc = pApi->xColumnText(pFts, iBestCol, &ctx.zIn, &ctx.nIn);
  }
  if( rc==SQLITE_OK && nColSize==0 ){
    rc = pApi->xColumnSize(pFts, iBestCol, &nColSize);
  }
  if( ctx.zIn ){
    if( rc==SQLITE_OK ){
      rc = fts5CInstIterInit(pApi, pFts, iBestCol, &ctx.iter);
    }









    ctx.iRangeStart = iBestStart;
    ctx.iRangeEnd = iBestStart + nToken - 1;

    if( iBestStart>0 ){
      fts5HighlightAppend(&rc, &ctx, zEllips, -1);
    }

      rc = pApi->xTokenize(pFts, ctx.zIn, ctx.nIn, (void*)&ctx,fts5HighlightCb);
    }
    if( ctx.iRangeEnd>=(nColSize-1) ){
      fts5HighlightAppend(&rc, &ctx, &ctx.zIn[ctx.iOff], ctx.nIn - ctx.iOff);
    }else{
      fts5HighlightAppend(&rc, &ctx, zEllips, -1);
    }
  }
  if( rc==SQLITE_OK ){
    sqlite3_result_text(pCtx, (const char*)ctx.zOut, -1, SQLITE_TRANSIENT);
  }else{
    sqlite3_result_error_code(pCtx, rc);
  }
  sqlite3_free(ctx.zOut);

  sqlite3_free(aSeen);
  sqlite3_free(sFinder.aFirst);
}

/************************************************************************/

/*
** The first time the bm25() function is called for a query, an instance
** of the following structure is allocated and populated.

  1.6 {o o o o o X o} {o o o o o [X] o}
  1.7 {o o o o o o X} {o o o o o o [X]}

  2.1 {X o o o o o o o} {[X] o o o o o o...}
  2.2 {o X o o o o o o} {o [X] o o o o o...}
  2.3 {o o X o o o o o} {o o [X] o o o o...}
  2.4 {o o o X o o o o} {o o o [X] o o o...}
  2.5 {o o o o X o o o} {o o o o [X] o o...}
  2.6 {o o o o o X o o} {o o o o o [X] o...}
  2.7 {o o o o o o X o} {o o o o o o [X]...}
  2.8 {o o o o o o o X} {...o o o o o o [X]}

  2.9  {o o o o o o o X o}       {...o o o o o [X] o}
  2.10 {o o o o o o o X o o}     {...o o o o [X] o o}
  2.11 {o o o o o o o X o o o}   {...o o o [X] o o o}
  2.12 {o o o o o o o X o o o o} {...o o o [X] o o o...}


  3.1 {X o o o o o o o o} {[X] o o o o o o...}
  3.2 {o X o o o o o o o} {o [X] o o o o o...}
  3.3 {o o X o o o o o o} {o o [X] o o o o...}
  3.4 {o o o X o o o o o} {o o o [X] o o o...}

  3.5 {o o o o o o o X o o o o} {...o o o [X] o o o...}
  3.6 {o o o o o o o o X o o o} {...o o o [X] o o o}
  3.7 {o o o o o o o o o X o o} {...o o o o [X] o o}
  3.8 {o o o o o o o o o o X o} {...o o o o o [X] o}
  3.9 {o o o o o o o o o o o X} {...o o o o o o [X]}

  4.1 {X o o o o o X o o} {[X] o o o o o [X]...}
  4.2 {o o o o o o o X o o o o o X o} {...[X] o o o o o [X]...}
  4.3 {o o o o o o o o X o o o o o X} {...[X] o o o o o [X]}

  5.1 {X o o o o X o o o} {[X] o o o o [X] o...}
  5.2 {o o o o o o o X o o o o X o o} {...[X] o o o o [X] o...}
  5.3 {o o o o o o o o X o o o o X o} {...[X] o o o o [X] o}
  5.4 {o o o o o o o o o X o o o o X} {...o [X] o o o o [X]}

  6.1 {X o o o X o o o} {[X] o o o [X] o o...}
  6.2 {o X o o o X o o o} {o [X] o o o [X] o...}
  6.3 {o o o o o o o X o o o X o o} {...o [X] o o o [X] o...}
  6.4 {o o o o o o o o X o o o X o} {...o [X] o o o [X] o}
  6.5 {o o o o o o o o o X o o o X} {...o o [X] o o o [X]}

  7.1 {X o o X o o o o o} {[X] o o [X] o o o...}
  7.2 {o X o o X o o o o} {o [X] o o [X] o o...}
  7.3 {o o o o o o o X o o X o o o} {...o [X] o o [X] o o...}
  7.4 {o o o o o o o o X o o X o o} {...o [X] o o [X] o o}
  7.5 {o o o o o o o o o X o o X o} {...o o [X] o o [X] o}
  7.6 {o o o o o o o o o o X o o X} {...o o o [X] o o [X]}

  8.1 {o o o o o o o o o X o o o o o o o o o o o o o o o o X X X o o o}
      {...o o [X] [X] [X] o o...}
  8.2 {o o o o o o o. o o X o o o o o o o o o o o o o o o o X X X o o o} 
      {...o o [X] o o o o...}
  8.3 {o o o o X o o o o o o o o o o o o o o o o o o o o o X X X o o o} 
      {o o o o [X] o o...}
} {
  do_snippet_test 1.$tn $doc X $res
}

if {[detail_is_full]} {
  foreach {tn doc res} {
    1.1 {X Y o o o o o} {[X Y] o o o o o}
    1.2 {o X Y o o o o} {o [X Y] o o o o}
    1.3 {o o X Y o o o} {o o [X Y] o o o}
    1.4 {o o o X Y o o} {o o o [X Y] o o}
    1.5 {o o o o X Y o} {o o o o [X Y] o}
    1.6 {o o o o o X Y} {o o o o o [X Y]}

    2.1 {X Y o o o o o o} {[X Y] o o o o o...}
    2.2 {o X Y o o o o o} {o [X Y] o o o o...}
    2.3 {o o X Y o o o o} {o o [X Y] o o o...}
    2.4 {o o o o o o o X Y o o o} {...o o [X Y] o o o}
    2.5 {o o o o o o o o X Y o o} {...o o o [X Y] o o}
    2.6 {o o o o o o o o o X Y o} {...o o o o [X Y] o}
    2.7 {o o o o o o o o o o X Y} {...o o o o o [X Y]}

    3.1 {X Y o o o o o o o} {[X Y] o o o o o...}
    3.2 {o X Y o o o o o o} {o [X Y] o o o o...}
    3.3 {o o X Y o o o o o} {o o [X Y] o o o...}
    3.4 {o o o o o o o X Y o o o o} {...o o [X Y] o o o...}
    3.5 {o o o o o o o o X Y o o o} {...o o [X Y] o o o}
    3.6 {o o o o o o o o o X Y o o} {...o o o [X Y] o o}
    3.7 {o o o o o o o o o o X Y o} {...o o o o [X Y] o}
    3.8 {o o o o o o o o o o o X Y} {...o o o o o [X Y]}
  } {
    do_snippet_test 2.$tn $doc "X + Y" $res
  }
}

do_execsql_test 4.0 {
  CREATE VIRTUAL TABLE x1 USING fts5(a, b);
  INSERT INTO x1 VALUES('xyz', '1 2 3 4 5 6 7 8 9 10 11 12 13');
  SELECT snippet(x1, 1, '[', ']', '...', 5) FROM x1('xyz');
} {
  {1 2 3 4 5...}
}

do_execsql_test 5.0 {
  CREATE VIRTUAL TABLE p1 USING fts5(a, b);
  INSERT INTO p1 VALUES(
    'x a a a a a a a a a a',
    'a a a a a a a a a a a a a a a a a a a x'
  );
}
do_execsql_test 5.1 {
  SELECT snippet(p1, 0, '[', ']', '...', 6) FROM p1('x');
} {{[x] a a a a a...}}

} ;# foreach_detail_mode 

finish_test

     the maximum x value.
  }
  3 "ROW" {
     ...returns the value of y on the same [row] that contains 
     the maximum x value.
  }
  4 "rollback" {
     Pending statements no longer block [ROLLBACK]. Instead, the pending
     statement will return SQLITE_ABORT upon...
  }
  5 "rOllback" {
     Pending statements no longer block [ROLLBACK]. Instead, the pending
     statement will return SQLITE_ABORT upon...
  }
  6 "lang*" {
     Added support for the FTS4 [languageid] option.
  }
} {
  do_test 2.$tn {
    set q [mapdoc $query]

    );
    DELETE FROM t2;
    INSERT INTO t2 VALUES(1,
        X'0000000000000000111111111111111122222222222222223333333FFF333333'
    );
  }

  4 {
    CREATE TABLE x1(a, b, c, PRIMARY KEY(a, b, c));
    INSERT INTO x1 VALUES('u', 'v', NULL);
    INSERT INTO x1 VALUES('x', 'y', 'z');
    INSERT INTO x1 VALUES('a', NULL, 'b');
  } {
    INSERT INTO x1 VALUES('a', 'b', 'c');
  }

} {
  catch { db close }

  forcedelete test.db test.db2
  sqlite3 db test.db
  db eval "$init"
  sqlite3 db test.db2

      db2 eval { INSERT INTO t1(t1) VALUES('integrity-check') }
    } {}

    db close
    db2 close
  }
}


finish_test

** Instead of a regular table, the RBU database may also contain virtual
** tables or view named using the data_<target> naming scheme. 
**
** Instead of the plain data_<target> naming scheme, RBU database tables 
** may also be named data<integer>_<target>, where <integer> is any sequence
** of zero or more numeric characters (0-9). This can be significant because
** tables within the RBU database are always processed in order sorted by 
** name. By judicious selection of the <integer> portion of the names
** of the RBU tables the user can therefore control the order in which they
** are processed. This can be useful, for example, to ensure that "external
** content" FTS4 tables are updated before their underlying content tables.
**
** If the target database table is a virtual table or a table that has no
** PRIMARY KEY declaration, the data_% table must also contain a column 
** named "rbu_rowid". This column is mapped to the tables implicit primary 

  memset(pCsr, 0, sizeof(RtreeCursor));
  pCsr->base.pVtab = (sqlite3_vtab*)pRtree;

  pCsr->iStrategy = idxNum;
  if( idxNum==1 ){
    /* Special case - lookup by rowid. */
    RtreeNode *pLeaf;        /* Leaf on which the required cell resides */
    RtreeSearchPoint *p;     /* Search point for the leaf */
    i64 iRowid = sqlite3_value_int64(argv[0]);
    i64 iNode = 0;
    rc = findLeafNode(pRtree, iRowid, &pLeaf, &iNode);
    if( rc==SQLITE_OK && pLeaf!=0 ){
      p = rtreeSearchPointNew(pCsr, RTREE_ZERO, 0);
      assert( p!=0 );  /* Always returns pCsr->sPoint */
      pCsr->aNode[0] = pLeaf;

proc do_common_sql {sql} {
  execsql $sql db
  execsql $sql db2
}

proc changeset_from_sql {sql {dbname main}} {
  if {$dbname == "main"} {
    return [sql_exec_changeset db $sql]
  }
  set rc [catch {
    sqlite3session S db $dbname
    db eval "SELECT name FROM $dbname.sqlite_master WHERE type = 'table'" {
      S attach $name
    }
    db eval $sql
    S changeset

  void *pB,                       /* Pointer to buffer containing changeset B */
  int *pnOut,                     /* OUT: Number of bytes in output changeset */
  void **ppOut                    /* OUT: Buffer containing output changeset */
);


/*
** CAPI3REF: Changegroup Handle
*/
typedef struct sqlite3_changegroup sqlite3_changegroup;

/*
** CAPI3REF: Create A New Changegroup Object
**
** An sqlite3_changegroup object is used to combine two or more changesets
** (or patchsets) into a single changeset (or patchset). A single changegroup
** object may combine changesets or patchsets, but not both. The output is
** always in the same format as the input.
**
** If successful, this function returns SQLITE_OK and populates (*pp) with

** As well as the regular sqlite3changegroup_add() and 
** sqlite3changegroup_output() functions, also available are the streaming
** versions sqlite3changegroup_add_strm() and sqlite3changegroup_output_strm().
*/
int sqlite3changegroup_new(sqlite3_changegroup **pp);

/*
** CAPI3REF: Add A Changeset To A Changegroup
**
** Add all changes within the changeset (or patchset) in buffer pData (size
** nData bytes) to the changegroup. 
**
** If the buffer contains a patchset, then all prior calls to this function
** on the same changegroup object must also have specified patchsets. Or, if
** the buffer contains a changeset, so must have the earlier calls to this
** function. Otherwise, SQLITE_ERROR is returned and no changes are added

** final contents of the changegroup is undefined.
**
** If no error occurs, SQLITE_OK is returned.
*/
int sqlite3changegroup_add(sqlite3_changegroup*, int nData, void *pData);

/*
** CAPI3REF: Obtain A Composite Changeset From A Changegroup
**
** Obtain a buffer containing a changeset (or patchset) representing the
** current contents of the changegroup. If the inputs to the changegroup
** were themselves changesets, the output is a changeset. Or, if the
** inputs were patchsets, the output is also a patchset.
**
** As with the output of the sqlite3session_changeset() and
** sqlite3session_patchset() functions, all changes related to a single

int sqlite3changegroup_output(
  sqlite3_changegroup*,
  int *pnData,                    /* OUT: Size of output buffer in bytes */
  void **ppData                   /* OUT: Pointer to output buffer */
);

/*
** CAPI3REF: Delete A Changegroup Object
*/
void sqlite3changegroup_delete(sqlite3_changegroup*);

/*
** CAPI3REF: Apply A Changeset To A Database
**
** Apply a changeset to a database. This function attempts to update the

typedef struct TestStreamInput TestStreamInput;
struct TestStreamInput {
  int nStream;                    /* Maximum chunk size */
  unsigned char *aData;           /* Pointer to buffer containing data */
  int nData;                      /* Size of buffer aData in bytes */
  int iData;                      /* Bytes of data already read by sessions */
};

/*
** Extract an sqlite3* db handle from the object passed as the second
** argument. If successful, set *pDb to point to the db handle and return
** TCL_OK. Otherwise, return TCL_ERROR.
*/
static int dbHandleFromObj(Tcl_Interp *interp, Tcl_Obj *pObj, sqlite3 **pDb){
  Tcl_CmdInfo info;
  if( 0==Tcl_GetCommandInfo(interp, Tcl_GetString(pObj), &info) ){
    Tcl_AppendResult(interp, "no such handle: ", Tcl_GetString(pObj), 0);
    return TCL_ERROR;
  }

  *pDb = *(sqlite3 **)info.objClientData;
  return TCL_OK;
}

/*************************************************************************
** The following code is copied byte-for-byte from the sessions module
** documentation.  It is used by some of the sessions modules tests to
** ensure that the example in the documentation does actually work.
*/ 
/*
** Argument zSql points to a buffer containing an SQL script to execute 
** against the database handle passed as the first argument. As well as
** executing the SQL script, this function collects a changeset recording
** all changes made to the "main" database file. Assuming no error occurs,
** output variables (*ppChangeset) and (*pnChangeset) are set to point
** to a buffer containing the changeset and the size of the changeset in
** bytes before returning SQLITE_OK. In this case it is the responsibility
** of the caller to eventually free the changeset blob by passing it to
** the sqlite3_free function.
**
** Or, if an error does occur, return an SQLite error code. The final
** value of (*pChangeset) and (*pnChangeset) are undefined in this case.
*/
int sql_exec_changeset(
  sqlite3 *db,                  /* Database handle */
  const char *zSql,             /* SQL script to execute */
  int *pnChangeset,             /* OUT: Size of changeset blob in bytes */
  void **ppChangeset            /* OUT: Pointer to changeset blob */
){
  sqlite3_session *pSession = 0;
  int rc;

  /* Create a new session object */
  rc = sqlite3session_create(db, "main", &pSession);

  /* Configure the session object to record changes to all tables */
  if( rc==SQLITE_OK ) rc = sqlite3session_attach(pSession, NULL);

  /* Execute the SQL script */
  if( rc==SQLITE_OK ) rc = sqlite3_exec(db, zSql, 0, 0, 0);

  /* Collect the changeset */
  if( rc==SQLITE_OK ){
    rc = sqlite3session_changeset(pSession, pnChangeset, ppChangeset);
  }

  /* Delete the session object */
  sqlite3session_delete(pSession);

  return rc;
}
/************************************************************************/

/*
** Tclcmd: sql_exec_changeset DB SQL
*/
static int SQLITE_TCLAPI test_sql_exec_changeset(
  void * clientData,
  Tcl_Interp *interp,
  int objc,
  Tcl_Obj *CONST objv[]
){
  const char *zSql;
  sqlite3 *db;
  void *pChangeset;
  int nChangeset;
  int rc;

  if( objc!=3 ){
    Tcl_WrongNumArgs(interp, 1, objv, "DB SQL");
    return TCL_ERROR;
  }
  if( dbHandleFromObj(interp, objv[1], &db) ) return TCL_ERROR;
  zSql = (const char*)Tcl_GetString(objv[2]);

  rc = sql_exec_changeset(db, zSql, &nChangeset, &pChangeset);
  if( rc!=SQLITE_OK ){
    Tcl_ResetResult(interp);
    Tcl_AppendResult(interp, "error in sql_exec_changeset()", 0);
    return TCL_ERROR;
  }

  Tcl_SetObjResult(interp, Tcl_NewByteArrayObj(pChangeset, nChangeset));
  sqlite3_free(pChangeset);
  return TCL_OK;
}



#define SESSION_STREAM_TCL_VAR "sqlite3session_streams"

/*
** Attempt to find the global variable zVar within interpreter interp
** and extract an integer value from it. Return this value.
**

    return test_session_error(interp, rc, 0);
  }

  return TCL_OK;
}

int TestSession_Init(Tcl_Interp *interp){
  struct Cmd {
    const char *zCmd;
    Tcl_ObjCmdProc *xProc;
  } aCmd[] = {
    { "sqlite3session", test_sqlite3session },

    { "sqlite3session_foreach", test_sqlite3session_foreach },


    { "sqlite3changeset_invert", test_sqlite3changeset_invert },


    { "sqlite3changeset_concat", test_sqlite3changeset_concat },


    { "sqlite3changeset_apply", test_sqlite3changeset_apply },


    { "sqlite3changeset_apply_replace_all", 
      test_sqlite3changeset_apply_replace_all },
    { "sql_exec_changeset", test_sql_exec_changeset },
  };
  int i;

  for(i=0; i<sizeof(aCmd)/sizeof(struct Cmd); i++){
    struct Cmd *p = &aCmd[i];
    Tcl_CreateObjCommand(interp, p->zCmd, p->xProc, 0, 0);
  }

  return TCL_OK;
}

#endif /* SQLITE_TEST && SQLITE_SESSION && SQLITE_PREUPDATE_HOOK */

    p->pDest = findBtree(pDestDb, pDestDb, zDestDb);
    p->pDestDb = pDestDb;
    p->pSrcDb = pSrcDb;
    p->iNext = 1;
    p->isAttached = 0;

    if( 0==p->pSrc || 0==p->pDest 

     || checkReadTransaction(pDestDb, p->pDest)!=SQLITE_OK 
     ){
      /* One (or both) of the named databases did not exist or an OOM
      ** error was hit. Or there is a transaction open on the destination
      ** database. The error has already been written into the pDestDb 
      ** handle. All that is left to do here is free the sqlite3_backup 
      ** structure.  */

    */
    if( p->pDestDb && p->pSrc->pBt->inTransaction==TRANS_WRITE ){
      rc = SQLITE_BUSY;
    }else{
      rc = SQLITE_OK;
    }









    /* If there is no open read-transaction on the source database, open
    ** one now. If a transaction is opened here, then it will be closed
    ** before this function exits.
    */
    if( rc==SQLITE_OK && 0==sqlite3BtreeIsInReadTrans(p->pSrc) ){
      rc = sqlite3BtreeBeginTrans(p->pSrc, 0);
      bCloseTrans = 1;
    }

    /* If the destination database has not yet been locked (i.e. if this
    ** is the first call to backup_step() for the current backup operation),
    ** try to set its page size to the same as the source database. This
    ** is especially important on ZipVFS systems, as in that case it is
    ** not possible to create a database file that uses one page size by
    ** writing to it with another.  */
    if( p->bDestLocked==0 && rc==SQLITE_OK && setDestPgsz(p)==SQLITE_NOMEM ){
      rc = SQLITE_NOMEM;
    }

    /* Lock the destination database, if it is not locked already. */
    if( SQLITE_OK==rc && p->bDestLocked==0
     && SQLITE_OK==(rc = sqlite3BtreeBeginTrans(p->pDest, 2)) 
    ){
      p->bDestLocked = 1;
      sqlite3BtreeGetMeta(p->pDest, BTREE_SCHEMA_VERSION, &p->iDestSchema);
    }

    /* Do not allow backup if the destination database is in WAL mode
    ** and the page sizes are different between source and destination */
    pgszSrc = sqlite3BtreeGetPageSize(p->pSrc);
    pgszDest = sqlite3BtreeGetPageSize(p->pDest);
    destMode = sqlite3PagerGetJournalMode(sqlite3BtreePager(p->pDest));
    if( SQLITE_OK==rc && destMode==PAGER_JOURNALMODE_WAL && pgszSrc!=pgszDest ){

  /* Register all built-in functions, but do not attempt to read the
  ** database schema yet. This is delayed until the first time the database
  ** is accessed.
  */
  sqlite3Error(db, SQLITE_OK);
  sqlite3RegisterPerConnectionBuiltinFunctions(db);
  rc = sqlite3_errcode(db);

#ifdef SQLITE_ENABLE_FTS5
  /* Register any built-in FTS5 module before loading the automatic
  ** extensions. This allows automatic extensions to register FTS5 
  ** tokenizers and auxiliary functions.  */
  if( !db->mallocFailed && rc==SQLITE_OK ){
    rc = sqlite3Fts5Init(db);
  }
#endif

  /* Load automatic extensions - extensions that have been registered
  ** using the sqlite3_automatic_extension() API.
  */

  if( rc==SQLITE_OK ){
    sqlite3AutoLoadExtensions(db);
    rc = sqlite3_errcode(db);
    if( rc!=SQLITE_OK ){
      goto opendb_out;
    }
  }

  }
#endif

#ifdef SQLITE_ENABLE_FTS3 /* automatically defined by SQLITE_ENABLE_FTS4 */
  if( !db->mallocFailed && rc==SQLITE_OK ){
    rc = sqlite3Fts3Init(db);
  }






#endif

#ifdef SQLITE_ENABLE_ICU
  if( !db->mallocFailed && rc==SQLITE_OK ){
    rc = sqlite3IcuInit(db);
  }
#endif

** then savepoint iSavepoint is also destroyed.
**
** This function may return SQLITE_NOMEM if a memory allocation fails,
** or an IO error code if an IO error occurs while rolling back a 
** savepoint. If no errors occur, SQLITE_OK is returned.
*/ 
int sqlite3PagerSavepoint(Pager *pPager, int op, int iSavepoint){
  int rc = pPager->errCode;
  
#ifdef SQLITE_ENABLE_ZIPVFS
  if( op==SAVEPOINT_RELEASE ) rc = SQLITE_OK;
#endif

  assert( op==SAVEPOINT_RELEASE || op==SAVEPOINT_ROLLBACK );
  assert( iSavepoint>=0 || op==SAVEPOINT_ROLLBACK );

  if( rc==SQLITE_OK && iSavepoint<pPager->nSavepoint ){
    int ii;            /* Iterator variable */
    int nNew;          /* Number of remaining savepoints after this op. */

    ** the database file, so the playback operation can be skipped.
    */
    else if( pagerUseWal(pPager) || isOpen(pPager->jfd) ){
      PagerSavepoint *pSavepoint = (nNew==0)?0:&pPager->aSavepoint[nNew-1];
      rc = pagerPlaybackSavepoint(pPager, pSavepoint);
      assert(rc!=SQLITE_DONE);
    }
    
#ifdef SQLITE_ENABLE_ZIPVFS
    /* If the cache has been modified but the savepoint cannot be rolled 
    ** back journal_mode=off, put the pager in the error state. This way,
    ** if the VFS used by this pager includes ZipVFS, the entire transaction
    ** can be rolled back at the ZipVFS level.  */
    else if( 
        pPager->journalMode==PAGER_JOURNALMODE_OFF 
     && pPager->eState>=PAGER_WRITER_CACHEMOD
    ){
      pPager->errCode = SQLITE_ABORT;
      pPager->eState = PAGER_ERROR;
    }
#endif
  }

  return rc;
}

/*
** Return the full pathname of the database file.

    }
    sqlite3TreeViewPop(pView);
  }
}


/*
** Generate a human-readable description of a Select object.
*/
void sqlite3TreeViewSelect(TreeView *pView, const Select *p, u8 moreToFollow){
  int n = 0;
  int cnt = 0;
  pView = sqlite3TreeViewPush(pView, moreToFollow);
  if( p->pWith ){
    sqlite3TreeViewWith(pView, p->pWith, 1);

  sqlite3VtabLock(pVTab);
}

/*
** This function is invoked by the vdbe to call the xCreate method
** of the virtual table named zTab in database iDb. 
**
** If an error occurs, *pzErr is set to point to an English language
** description of the error and an SQLITE_XXX error code is returned.
** In this case the caller must call sqlite3DbFree(db, ) on *pzErr.
*/
int sqlite3VtabCallCreate(sqlite3 *db, int iDb, const char *zTab, char **pzErr){
  int rc = SQLITE_OK;
  Table *pTab;
  Module *pMod;

  if {$rc && ($errcode == "SQLITE_NOMEM" || $errcode == "SQLITE_IOERR_NOMEM")} {
    error "out of memory"
  }
} -cleanup {
  catch { B finish }
  db2 close
}

reset_db
do_execsql_test 3.0 {
  PRAGMA page_size = 16384;
  BEGIN;
  CREATE TABLE t1(a, b);
  INSERT INTO t1 VALUES(1, 2);
  COMMIT;
}

do_faultsim_test 3 -faults oom* -prep {
  catch { db close }

  forcedelete test2.db
  sqlite3 db2 test2.db
  sqlite3 db test.db
  sqlite3_backup B db2 main db main
} -body {

  set rc [B step 50]
  if {$rc == "SQLITE_NOMEM" || $rc == "SQLITE_IOERR_NOMEM"} {
    error "out of memory"
  }

} -test {
  faultsim_test_result {0 {}} 
  faultsim_integrity_check
  
  # Finalize the backup.
  catch { B finish }
}

finish_test

  strPrintf(pSql, "SELECT ");
  strPrintfArray(pSql, ", ", "%s", azCol, -1);
  strPrintf(pSql, ", 0, ");       /* Set ota_control to 0 for an insert */
  strPrintfArray(pSql, ", ", "NULL", azCol, -1);
  strPrintf(pSql, " FROM aux.%Q AS n WHERE NOT EXISTS (\n", zTab);
  strPrintf(pSql, "    SELECT 1 FROM ", zTab);
  strPrintf(pSql, " main.%Q AS o WHERE ", zTab);
  strPrintfArray(pSql, " AND ", "(n.%Q = o.%Q)", azCol, nPK);
  strPrintf(pSql, "\n) AND ");
  strPrintfArray(pSql, " AND ", "(n.%Q IS NOT NULL)", azCol, nPK);

  /* Deleted rows: */
  strPrintf(pSql, "\nUNION ALL\nSELECT ");
  strPrintfArray(pSql, ", ", "%s", azCol, nPK);
  if( azCol[nPK] ){
    strPrintf(pSql, ", ");
    strPrintfArray(pSql, ", ", "NULL", &azCol[nPK], -1);
  }
  strPrintf(pSql, ", 1, ");       /* Set ota_control to 1 for a delete */
  strPrintfArray(pSql, ", ", "NULL", azCol, -1);
  strPrintf(pSql, " FROM main.%Q AS n WHERE NOT EXISTS (\n", zTab);
  strPrintf(pSql, "    SELECT 1 FROM ", zTab);
  strPrintf(pSql, " aux.%Q AS o WHERE ", zTab);
  strPrintfArray(pSql, " AND ", "(n.%Q = o.%Q)", azCol, nPK);
  strPrintf(pSql, "\n) AND ");
  strPrintfArray(pSql, " AND ", "(n.%Q IS NOT NULL)", azCol, nPK);

  /* Updated rows. If all table columns are part of the primary key, there 
  ** can be no updates. In this case this part of the compound SELECT can
  ** be omitted altogether. */
  if( azCol[nPK] ){
    strPrintf(pSql, "\nUNION ALL\nSELECT ");
    strPrintfArray(pSql, ", ", "n.%s", azCol, nPK);

    strPrintfArray(pSql, ", ", "NULL", azCol, nPK);
    strPrintf(pSql, ",\n");
    strPrintfArray(pSql, " ,\n", 
        "    CASE WHEN n.%s IS o.%s THEN NULL ELSE o.%s END", &azCol[nPK], -1
    );

    strPrintf(pSql, "\nFROM main.%Q AS o, aux.%Q AS n\nWHERE ", zTab, zTab);
    strPrintfArray(pSql, " AND ", "(n.%Q = o.%Q)", azCol, nPK);
    strPrintf(pSql, " AND ota_control LIKE '%%x%%'");
  }

  /* Now add an ORDER BY clause to sort everything by PK. */
  strPrintf(pSql, "\nORDER BY ");
  for(i=1; i<=nPK; i++) strPrintf(pSql, "%s%d", ((i>1)?", ":""), i);
}