}
  }

  /* If a content=xxx option was specified, the following:
  **
  **   1. Ignore any compress= and uncompress= options.
  **
  **   2. Ignore any column names that were specified as part of the 
  **      the CREATE VIRTUAL TABLE statement.
  **
  **   3. Determine the actual column names to use for the FTS table 
  **      based on the columns of the content= table.
  */
  if( rc==SQLITE_OK && zContent ){
    sqlite3_free(aCol); 
    sqlite3_free(zCompress); 
    sqlite3_free(zUncompress); 
    zCompress = 0;
    zUncompress = 0;


    aCol = 0;
    rc = fts3ContentColumns(db, argv[1], zContent, &aCol, &nCol, &nString);

    assert( rc!=SQLITE_OK || nCol>0 );
  }
  if( rc!=SQLITE_OK ) goto fts3_init_out;

  if( nCol==0 ){
    assert( nString==0 );
    aCol[0] = "content";
................................................................................
  sqlite3Fts3FreeDeferredTokens(pCsr);
  sqlite3_free(pCsr->aDoclist);
  sqlite3_free(pCsr->aMatchinfo);
  assert( ((Fts3Table *)pCsr->base.pVtab)->pSegments==0 );
  sqlite3_free(pCsr);
  return SQLITE_OK;
}


























/*
** Position the pCsr->pStmt statement so that it is on the row
** of the %_content table that contains the last match.  Return
** SQLITE_OK on success.  
*/
static int fts3CursorSeek(sqlite3_context *pContext, Fts3Cursor *pCsr){

  if( pCsr->isRequireSeek ){




    sqlite3_bind_int64(pCsr->pStmt, 1, pCsr->iPrevId);
    pCsr->isRequireSeek = 0;
    if( SQLITE_ROW==sqlite3_step(pCsr->pStmt) ){
      return SQLITE_OK;
    }else{
      int rc = sqlite3_reset(pCsr->pStmt);
      if( rc==SQLITE_OK ){
        Fts3Table *p = (Fts3Table *)pCsr->base.pVtab;
        if( p->zContentTbl==0 ){
          /* If no row was found and no error has occured, then the %_content
          ** table is missing a row that is present in the full-text index.
          ** The data structures are corrupt.
          */
          rc = SQLITE_CORRUPT_VTAB;
        }else{
          return SQLITE_OK;

        }
      }
      pCsr->isEof = 1;



      if( pContext ){
        sqlite3_result_error_code(pContext, rc);
      }
      return rc;
    }
  }else{
    return SQLITE_OK;
  }
}

/*
** 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.
................................................................................

  /* 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.
  */
  if( idxNum==FTS3_FULLSCAN_SEARCH ){
    const char *zTmpl = "SELECT %s ORDER BY rowid %s";
    zSql = sqlite3_mprintf(zTmpl, 

        p->zReadExprlist, (pCsr->bDesc ? "DESC" : "ASC")
    );
  }else{
    const char *zTmpl = "SELECT %s WHERE rowid = ?";
    zSql = sqlite3_mprintf(zTmpl, p->zReadExprlist);
  }
  if( !zSql ) return SQLITE_NOMEM;
  rc = sqlite3_prepare_v2(p->db, zSql, -1, &pCsr->pStmt, 0);
  sqlite3_free(zSql);
  if( rc!=SQLITE_OK ) return rc;



  if( idxNum==FTS3_DOCID_SEARCH ){


    rc = sqlite3_bind_value(pCsr->pStmt, 1, apVal[0]);
    if( rc!=SQLITE_OK ) return rc;
  }



  return fts3NextMethod(pCursor);
}

/* 
** This is the xEof method of the virtual table. SQLite calls this 
** routine to find out if it has reached the end of a result set.
*/

    }
  }

  /* If a content=xxx option was specified, the following:
  **
  **   1. Ignore any compress= and uncompress= options.
  **
  **   2. If no column names were specified as part of the CREATE VIRTUAL
  **      TABLE statement, use all columns from the content table.



  */
  if( rc==SQLITE_OK && zContent ){

    sqlite3_free(zCompress); 
    sqlite3_free(zUncompress); 
    zCompress = 0;
    zUncompress = 0;
    if( nCol==0 ){
      sqlite3_free(aCol); 
      aCol = 0;
      rc = fts3ContentColumns(db, argv[1], zContent, &aCol, &nCol, &nString);
    }
    assert( rc!=SQLITE_OK || nCol>0 );
  }
  if( rc!=SQLITE_OK ) goto fts3_init_out;

  if( nCol==0 ){
    assert( nString==0 );
    aCol[0] = "content";
................................................................................
  sqlite3Fts3FreeDeferredTokens(pCsr);
  sqlite3_free(pCsr->aDoclist);
  sqlite3_free(pCsr->aMatchinfo);
  assert( ((Fts3Table *)pCsr->base.pVtab)->pSegments==0 );
  sqlite3_free(pCsr);
  return SQLITE_OK;
}

/*
** If pCsr->pStmt has not been prepared (i.e. if pCsr->pStmt==0), then
** compose and prepare an SQL statement of the form:
**
**    "SELECT <columns> FROM %_content WHERE rowid = ?"
**
** (or the equivalent for a content=xxx table) and set pCsr->pStmt to
** it. If an error occurs, return an SQLite error code.
**
** Otherwise, set *ppStmt to point to pCsr->pStmt and return SQLITE_OK.
*/
static int fts3CursorSeekStmt(Fts3Cursor *pCsr, sqlite3_stmt **ppStmt){
  int rc = SQLITE_OK;
  if( pCsr->pStmt==0 ){
    Fts3Table *p = (Fts3Table *)pCsr->base.pVtab;
    char *zSql;
    zSql = sqlite3_mprintf("SELECT %s WHERE rowid = ?", p->zReadExprlist);
    if( !zSql ) return SQLITE_NOMEM;
    rc = sqlite3_prepare_v2(p->db, zSql, -1, &pCsr->pStmt, 0);
    sqlite3_free(zSql);
  }
  *ppStmt = pCsr->pStmt;
  return rc;
}

/*
** Position the pCsr->pStmt statement so that it is on the row
** of the %_content table that contains the last match.  Return
** SQLITE_OK on success.  
*/
static int fts3CursorSeek(sqlite3_context *pContext, Fts3Cursor *pCsr){
  int rc = SQLITE_OK;
  if( pCsr->isRequireSeek ){
    sqlite3_stmt *pStmt = 0;

    rc = fts3CursorSeekStmt(pCsr, &pStmt);
    if( rc==SQLITE_OK ){
      sqlite3_bind_int64(pCsr->pStmt, 1, pCsr->iPrevId);
      pCsr->isRequireSeek = 0;
      if( SQLITE_ROW==sqlite3_step(pCsr->pStmt) ){
        return SQLITE_OK;
      }else{
        rc = sqlite3_reset(pCsr->pStmt);

        if( rc==SQLITE_OK && ((Fts3Table *)pCsr->base.pVtab)->zContentTbl==0 ){

          /* If no row was found and no error has occured, then the %_content
          ** table is missing a row that is present in the full-text index.
          ** The data structures are corrupt.  */

          rc = SQLITE_CORRUPT_VTAB;


          pCsr->isEof = 1;
        }
      }

    }
  }

  if( rc!=SQLITE_OK && pContext ){
    sqlite3_result_error_code(pContext, rc);
  }
  return rc;




}

/*
** 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.
................................................................................

  /* 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.
  */
  if( idxNum==FTS3_FULLSCAN_SEARCH ){

    zSql = sqlite3_mprintf(
        "SELECT %s ORDER BY rowid %s",
        p->zReadExprlist, (pCsr->bDesc ? "DESC" : "ASC")
    );
    if( zSql ){




      rc = sqlite3_prepare_v2(p->db, zSql, -1, &pCsr->pStmt, 0);
      sqlite3_free(zSql);

    }else{
      rc = SQLITE_NOMEM;
    }
  }else if( idxNum==FTS3_DOCID_SEARCH ){
    rc = fts3CursorSeekStmt(pCsr, &pCsr->pStmt);
    if( rc==SQLITE_OK ){
      rc = sqlite3_bind_value(pCsr->pStmt, 1, apVal[0]);

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

  return fts3NextMethod(pCursor);
}

/* 
** This is the xEof method of the virtual table. SQLite calls this 
** routine to find out if it has reached the end of a result set.
*/

** write-locks on the %_segments and %_segdir ** tables). 
**
** We try to avoid this because if FTS3 returns any error when committing
** a transaction, the whole transaction will be rolled back. And this is
** not what users expect when they get SQLITE_LOCKED_SHAREDCACHE. It can
** still happen if the user reads data directly from the %_segments or
** %_segdir tables instead of going through FTS3 though.


*/
int sqlite3Fts3ReadLock(Fts3Table *p){
  int rc;                         /* Return code */
  sqlite3_stmt *pStmt;            /* Statement used to obtain lock */


  rc = fts3SqlStmt(p, SQL_SELECT_CONTENT_BY_ROWID, &pStmt, 0);
  if( rc==SQLITE_OK ){
    sqlite3_bind_null(pStmt, 1);
    sqlite3_step(pStmt);
    rc = sqlite3_reset(pStmt);
  }




  return rc;
}

/*
** Set *ppStmt to a statement handle that may be used to iterate through
** all rows in the %_segdir table, from oldest to newest. If successful,
** return SQLITE_OK. If an error occurs while preparing the statement, 

** write-locks on the %_segments and %_segdir ** tables). 
**
** We try to avoid this because if FTS3 returns any error when committing
** a transaction, the whole transaction will be rolled back. And this is
** not what users expect when they get SQLITE_LOCKED_SHAREDCACHE. It can
** still happen if the user reads data directly from the %_segments or
** %_segdir tables instead of going through FTS3 though.
**
** This reasoning does not apply to a content=xxx table.
*/
int sqlite3Fts3ReadLock(Fts3Table *p){
  int rc;                         /* Return code */
  sqlite3_stmt *pStmt;            /* Statement used to obtain lock */

  if( p->zContentTbl==0 ){
    rc = fts3SqlStmt(p, SQL_SELECT_CONTENT_BY_ROWID, &pStmt, 0);
    if( rc==SQLITE_OK ){
      sqlite3_bind_null(pStmt, 1);
      sqlite3_step(pStmt);
      rc = sqlite3_reset(pStmt);
    }
  }else{
    rc = SQLITE_OK;
  }

  return rc;
}

/*
** Set *ppStmt to a statement handle that may be used to iterate through
** all rows in the %_segdir table, from oldest to newest. If successful,
** return SQLITE_OK. If an error occurs while preparing the statement, 

#   5.* - Check that CREATE TABLE, DROP TABLE and ALTER TABLE correctly
#         ignore any %_content table when used with the content=xxx option.
#
#   6.* - Test the effects of messing with the schema of table xxx after
#         creating a content=xxx FTS index.
#

do_execsql_test 1.1 {
  CREATE TABLE t1(a, b, c);
  INSERT INTO t1 VALUES('w x', 'x y', 'y z');
  CREATE VIRTUAL TABLE ft1 USING fts4(content=t1);
}

do_execsql_test 1.2 {
  PRAGMA table_info(ft1);
} {
  0 a {} 0 {} 0 
  1 b {} 0 {} 0 
  2 c {} 0 {} 0
}

do_execsql_test 1.3 { SELECT *, rowid FROM ft1 } {{w x} {x y} {y z} 1}
do_execsql_test 1.4 { SELECT a, c FROM ft1 WHERE rowid=1 } {{w x} {y z}}

do_execsql_test 1.5 { INSERT INTO ft1(ft1) VALUES('rebuild') } {}
do_execsql_test 1.6 { SELECT rowid FROM ft1 WHERE ft1 MATCH 'x' } {1}
do_execsql_test 1.7 { SELECT rowid FROM ft1 WHERE ft1 MATCH 'a' } {}












#-------------------------------------------------------------------------
# The following block of tests - 2.* - test that a content=xxx FTS table
# can be queried. Also tested are cases where rows identified in the FTS
# are missing from the content table, and cases where the index is 
# inconsistent with the content table.
# 
................................................................................
} {2}

do_execsql_test 6.2.7 {
  DROP TABLE t7;
  CREATE TABLE t7(x);
}
do_catchsql_test 6.2.8 {
  SELECT rowid FROM ft7 WHERE ft7 MATCH '"A A"';
} {1 {SQL logic error or missing database}}
do_catchsql_test 6.2.9 {
  SELECT rowid FROM ft7 WHERE ft7 MATCH '"A A"';
} {1 {SQL logic error or missing database}}

db close
sqlite3 db test.db
do_catchsql_test 6.2.10 {
  SELECT rowid FROM ft7 WHERE ft7 MATCH '"A A"';
} {0 2}
do_catchsql_test 6.2.11 {
  SELECT rowid, * FROM ft7 WHERE ft7 MATCH '"A A"';
} {0 {2 {}}}

















finish_test

#   5.* - Check that CREATE TABLE, DROP TABLE and ALTER TABLE correctly
#         ignore any %_content table when used with the content=xxx option.
#
#   6.* - Test the effects of messing with the schema of table xxx after
#         creating a content=xxx FTS index.
#

do_execsql_test 1.1.1 {
  CREATE TABLE t1(a, b, c);
  INSERT INTO t1 VALUES('w x', 'x y', 'y z');
  CREATE VIRTUAL TABLE ft1 USING fts4(content=t1);
}

do_execsql_test 1.1.2 {
  PRAGMA table_info(ft1);
} {
  0 a {} 0 {} 0 
  1 b {} 0 {} 0 
  2 c {} 0 {} 0
}

do_execsql_test 1.1.3 { SELECT *, rowid FROM ft1 } {{w x} {x y} {y z} 1}
do_execsql_test 1.1.4 { SELECT a, c FROM ft1 WHERE rowid=1 } {{w x} {y z}}

do_execsql_test 1.1.5 { INSERT INTO ft1(ft1) VALUES('rebuild') } {}
do_execsql_test 1.1.6 { SELECT rowid FROM ft1 WHERE ft1 MATCH 'x' } {1}
do_execsql_test 1.1.7 { SELECT rowid FROM ft1 WHERE ft1 MATCH 'a' } {}

do_execsql_test 1.2.1 {
  DROP TABLE ft1;
  CREATE VIRTUAL TABLE ft1 USING fts4(content=t1, b);
  PRAGMA table_info(ft1);
} {
  0 b {} 0 {} 0 
}
do_execsql_test 1.2.2 { 
  SELECT *, rowid FROM ft1 
} {{x y} 1}

#-------------------------------------------------------------------------
# The following block of tests - 2.* - test that a content=xxx FTS table
# can be queried. Also tested are cases where rows identified in the FTS
# are missing from the content table, and cases where the index is 
# inconsistent with the content table.
# 
................................................................................
} {2}

do_execsql_test 6.2.7 {
  DROP TABLE t7;
  CREATE TABLE t7(x);
}
do_catchsql_test 6.2.8 {
  SELECT * FROM ft7 WHERE ft7 MATCH '"A A"';
} {1 {SQL logic error or missing database}}
do_catchsql_test 6.2.9 {
  SELECT * FROM ft7 WHERE ft7 MATCH '"A A"';
} {1 {SQL logic error or missing database}}

db close
sqlite3 db test.db
do_catchsql_test 6.2.10 {
  SELECT rowid FROM ft7 WHERE ft7 MATCH '"A A"';
} {0 2}
do_catchsql_test 6.2.11 {
  SELECT rowid, * FROM ft7 WHERE ft7 MATCH '"A A"';
} {0 {2 {}}}

#-------------------------------------------------------------------------
# Test cases 7.*
# 
do_execsql_test 7.1.1 {
  CREATE VIRTUAL TABLE ft8 USING fts4(content=nosuchtable, x);
  INSERT INTO ft8(docid, x) VALUES(13, 'U O N X G');
  INSERT INTO ft8(docid, x) VALUES(14, 'C J J U B');
  INSERT INTO ft8(docid, x) VALUES(15, 'N J Y G X');
  INSERT INTO ft8(docid, x) VALUES(16, 'R Y D O R');
  INSERT INTO ft8(docid, x) VALUES(17, 'I Y T Q O');
}

do_execsql_test 7.1.2 {
  SELECT docid FROM ft8 WHERE ft8 MATCH 'N';
} {13 15}

finish_test