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Overview
Comment:Candidate fix for ticket [6bfb98dfc0c]: Make sure invalid cursors drop all references to database pages prior to doing any insert or update.
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SHA1:322a5f086d9ee46017f750df81527799a54ae258
User & Date: drh 2013-03-27 03:15:23
Context
2013-03-27
17:20
In order to optimize out the ORDER BY clause, outer loops must generate values for ORDER BY terms that are unique or else the inner loops must generate no more than a single row. Fix for ticket [a179fe7465]. check-in: 2936f746 user: drh tags: trunk
15:04
A fix and test-case for the ORDER BY problem identified by ticket [a179fe7465]. This change causes sorting to occur in some cases where it is not strictly necessary. Further work is needed to avoid those extra sorts. check-in: 488089e6 user: drh tags: orderby-fix
03:15
Candidate fix for ticket [6bfb98dfc0c]: Make sure invalid cursors drop all references to database pages prior to doing any insert or update. check-in: 322a5f08 user: drh tags: trunk
2013-03-25
12:02
Add a second test for [38b1ae018f]. check-in: 5062db67 user: dan tags: trunk
Changes
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Changes to src/btree.c.

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** Clear (destroy) the BtShared.pHasContent bitvec. This should be
** invoked at the conclusion of each write-transaction.
*/
static void btreeClearHasContent(BtShared *pBt){
  sqlite3BitvecDestroy(pBt->pHasContent);
  pBt->pHasContent = 0;
}














/*
** Save the current cursor position in the variables BtCursor.nKey 
** and BtCursor.pKey. The cursor's state is set to CURSOR_REQUIRESEEK.
**
** The caller must ensure that the cursor is valid (has eState==CURSOR_VALID)
** prior to calling this routine.  
................................................................................
    }else{
      rc = SQLITE_NOMEM;
    }
  }
  assert( !pCur->apPage[0]->intKey || !pCur->pKey );

  if( rc==SQLITE_OK ){
    int i;
    for(i=0; i<=pCur->iPage; i++){
      releasePage(pCur->apPage[i]);
      pCur->apPage[i] = 0;
    }
    pCur->iPage = -1;
    pCur->eState = CURSOR_REQUIRESEEK;
  }

  invalidateOverflowCache(pCur);
  return rc;
}

................................................................................
** pExcept is used to modify the table (BtreeDelete() or BtreeInsert()).
*/
static int saveAllCursors(BtShared *pBt, Pgno iRoot, BtCursor *pExcept){
  BtCursor *p;
  assert( sqlite3_mutex_held(pBt->mutex) );
  assert( pExcept==0 || pExcept->pBt==pBt );
  for(p=pBt->pCursor; p; p=p->pNext){
    if( p!=pExcept && (0==iRoot || p->pgnoRoot==iRoot) && 
        p->eState==CURSOR_VALID ){
      int rc = saveCursorPosition(p);
      if( SQLITE_OK!=rc ){
        return rc;




      }
    }
  }
  return SQLITE_OK;
}

/*







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** Clear (destroy) the BtShared.pHasContent bitvec. This should be
** invoked at the conclusion of each write-transaction.
*/
static void btreeClearHasContent(BtShared *pBt){
  sqlite3BitvecDestroy(pBt->pHasContent);
  pBt->pHasContent = 0;
}

/*
** Release all of the apPage[] pages for a cursor.
*/
static void btreeReleaseAllCursorPages(BtCursor *pCur){
  int i;
  for(i=0; i<=pCur->iPage; i++){
    releasePage(pCur->apPage[i]);
    pCur->apPage[i] = 0;
  }
  pCur->iPage = -1;
}


/*
** Save the current cursor position in the variables BtCursor.nKey 
** and BtCursor.pKey. The cursor's state is set to CURSOR_REQUIRESEEK.
**
** The caller must ensure that the cursor is valid (has eState==CURSOR_VALID)
** prior to calling this routine.  
................................................................................
    }else{
      rc = SQLITE_NOMEM;
    }
  }
  assert( !pCur->apPage[0]->intKey || !pCur->pKey );

  if( rc==SQLITE_OK ){
    btreeReleaseAllCursorPages(pCur);





    pCur->eState = CURSOR_REQUIRESEEK;
  }

  invalidateOverflowCache(pCur);
  return rc;
}

................................................................................
** pExcept is used to modify the table (BtreeDelete() or BtreeInsert()).
*/
static int saveAllCursors(BtShared *pBt, Pgno iRoot, BtCursor *pExcept){
  BtCursor *p;
  assert( sqlite3_mutex_held(pBt->mutex) );
  assert( pExcept==0 || pExcept->pBt==pBt );
  for(p=pBt->pCursor; p; p=p->pNext){
    if( p!=pExcept && (0==iRoot || p->pgnoRoot==iRoot) ){
      if( p->eState==CURSOR_VALID ){
        int rc = saveCursorPosition(p);
        if( SQLITE_OK!=rc ){
          return rc;
        }
      }else{
        testcase( p->iPage>0 );
        btreeReleaseAllCursorPages(p);
      }
    }
  }
  return SQLITE_OK;
}

/*

Added test/tkt-6bfb98dfc0.test.



























































































































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# 2013 March 27
#
# 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. Specifically,
# it tests that ticket [6bfb98dfc0]
#
# The final INSERT in the script below reports that the database is
# corrupt (SQLITE_CORRUPT) and aborts even though the database is not
# corrupt.
#
#    PRAGMA page_size=512;
#    CREATE TABLE t1(x INTEGER PRIMARY KEY, y);
#    INSERT INTO t1 VALUES(1,randomblob(400));
#    INSERT INTO t1 VALUES(2,randomblob(400));
#    INSERT INTO t1 SELECT x+2, randomblob(400) FROM t1;
#    INSERT INTO t1 SELECT x+4, randomblob(400) FROM t1;
#    INSERT INTO t1 SELECT x+8, randomblob(400) FROM t1;
#    INSERT INTO t1 SELECT x+16, randomblob(400) FROM t1;
#    INSERT INTO t1 SELECT x+32, randomblob(400) FROM t1;
#    INSERT INTO t1 SELECT x+64, randomblob(400) FROM t1 WHERE x<10;
#    CREATE TRIGGER r1 AFTER INSERT ON t1 WHEN new.x=74 BEGIN
#      DELETE FROM t1;
#      INSERT INTO t1 VALUES(75, randomblob(400));
#      INSERT INTO t1 VALUES(76, randomblob(400));
#    END;
#    INSERT INTO t1 VALUES(74, randomblob(400));
#

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

do_test tkt-6bfb98dfc0.100 {
  db eval {
    PRAGMA page_size=512;
    CREATE TABLE t1(x INTEGER PRIMARY KEY, y);
    INSERT INTO t1 VALUES(1,randomblob(400));
    INSERT INTO t1 VALUES(2,randomblob(400));
    INSERT INTO t1 SELECT x+2, randomblob(400) FROM t1;
    INSERT INTO t1 SELECT x+4, randomblob(400) FROM t1;
    INSERT INTO t1 SELECT x+8, randomblob(400) FROM t1;
    INSERT INTO t1 SELECT x+16, randomblob(400) FROM t1;
    INSERT INTO t1 SELECT x+32, randomblob(400) FROM t1;
    INSERT INTO t1 SELECT x+64, randomblob(400) FROM t1 WHERE x<10;
    CREATE TRIGGER r1 AFTER INSERT ON t1 WHEN new.x=74 BEGIN
      DELETE FROM t1;
      INSERT INTO t1 VALUES(75, randomblob(400));
      INSERT INTO t1 VALUES(76, randomblob(400));
    END;
    INSERT INTO t1 VALUES(74, randomblob(400));
    SELECT x, length(y) FROM t1 ORDER BY x;
  }
} {75 400 76 400}
    
finish_test