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Comment:When an incremental blob cursor is invalidated (occurs when an SQL statement modifies or deletes the row the blob cursor points to) release all page references held by the cursor. Otherwise, the presence of these references may cause other code in btree.c to incorrectly infer that the database is corrupt.
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SHA1:82c3f2ba42f2c75ba6951cc2743148886a4dc0bc
User & Date: dan 2012-03-23 11:09:59
Context
2012-03-23
13:40
Fix another test case issue in trace2.test. check-in: 02a8e423 user: dan tags: fts4-incr-merge
11:09
When an incremental blob cursor is invalidated (occurs when an SQL statement modifies or deletes the row the blob cursor points to) release all page references held by the cursor. Otherwise, the presence of these references may cause other code in btree.c to incorrectly infer that the database is corrupt. check-in: 82c3f2ba user: dan tags: fts4-incr-merge
11:07
Update a couple of existing test cases. check-in: dcb8fa0f user: dan tags: fts4-incr-merge
Changes
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Changes to src/btree.c.

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  /* Assert that the caller has been consistent. If this cursor was opened
  ** expecting an index b-tree, then the caller should be inserting blob
  ** keys with no associated data. If the cursor was opened expecting an
  ** intkey table, the caller should be inserting integer keys with a
  ** blob of associated data.  */
  assert( (pKey==0)==(pCur->pKeyInfo==0) );

  /* If this is an insert into a table b-tree, invalidate any incrblob 
  ** cursors open on the row being replaced (assuming this is a replace
  ** operation - if it is not, the following is a no-op).  */
  if( pCur->pKeyInfo==0 ){
    invalidateIncrblobCursors(p, nKey, 0);
  }

  /* Save the positions of any other cursors open on this table.
  **
  ** In some cases, the call to btreeMoveto() below is a no-op. For
  ** example, when inserting data into a table with auto-generated integer
  ** keys, the VDBE layer invokes sqlite3BtreeLast() to figure out the 
  ** integer key to use. It then calls this function to actually insert the 
  ** data into the intkey B-Tree. In this case btreeMoveto() recognizes
  ** that the cursor is already where it needs to be and returns without
  ** doing any work. To avoid thwarting these optimizations, it is important
  ** not to clear the cursor here.
  */
  rc = saveAllCursors(pBt, pCur->pgnoRoot, pCur);
  if( rc ) return rc;








  if( !loc ){
    rc = btreeMoveto(pCur, pKey, nKey, appendBias, &loc);
    if( rc ) return rc;
  }
  assert( pCur->eState==CURSOR_VALID || (pCur->eState==CURSOR_INVALID && loc) );

  pPage = pCur->apPage[pCur->iPage];
................................................................................

  if( NEVER(pCur->aiIdx[pCur->iPage]>=pCur->apPage[pCur->iPage]->nCell) 
   || NEVER(pCur->eState!=CURSOR_VALID)
  ){
    return SQLITE_ERROR;  /* Something has gone awry. */
  }

  /* If this is a delete operation to remove a row from a table b-tree,
  ** invalidate any incrblob cursors open on the row being deleted.  */
  if( pCur->pKeyInfo==0 ){
    invalidateIncrblobCursors(p, pCur->info.nKey, 0);
  }

  iCellDepth = pCur->iPage;
  iCellIdx = pCur->aiIdx[iCellDepth];
  pPage = pCur->apPage[iCellDepth];
  pCell = findCell(pPage, iCellIdx);

  /* If the page containing the entry to delete is not a leaf page, move
  ** the cursor to the largest entry in the tree that is smaller than
................................................................................
  /* Save the positions of any other cursors open on this table before
  ** making any modifications. Make the page containing the entry to be 
  ** deleted writable. Then free any overflow pages associated with the 
  ** entry and finally remove the cell itself from within the page.  
  */
  rc = saveAllCursors(pBt, pCur->pgnoRoot, pCur);
  if( rc ) return rc;







  rc = sqlite3PagerWrite(pPage->pDbPage);
  if( rc ) return rc;
  rc = clearCell(pPage, pCell);
  dropCell(pPage, iCellIdx, cellSizePtr(pPage, pCell), &rc);
  if( rc ) return rc;

  /* If the cell deleted was not located on a leaf page, then the cursor
................................................................................
*/
int sqlite3BtreeClearTable(Btree *p, int iTable, int *pnChange){
  int rc;
  BtShared *pBt = p->pBt;
  sqlite3BtreeEnter(p);
  assert( p->inTrans==TRANS_WRITE );




  /* Invalidate all incrblob cursors open on table iTable (assuming iTable
  ** is the root of a table b-tree - if it is not, the following call is
  ** a no-op).  */
  invalidateIncrblobCursors(p, 0, 1);

  rc = saveAllCursors(pBt, (Pgno)iTable, 0);
  if( SQLITE_OK==rc ){
    rc = clearDatabasePage(pBt, (Pgno)iTable, 0, pnChange);
  }
  sqlite3BtreeLeave(p);
  return rc;
}

/*







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  /* Assert that the caller has been consistent. If this cursor was opened
  ** expecting an index b-tree, then the caller should be inserting blob
  ** keys with no associated data. If the cursor was opened expecting an
  ** intkey table, the caller should be inserting integer keys with a
  ** blob of associated data.  */
  assert( (pKey==0)==(pCur->pKeyInfo==0) );








  /* Save the positions of any other cursors open on this table.
  **
  ** In some cases, the call to btreeMoveto() below is a no-op. For
  ** example, when inserting data into a table with auto-generated integer
  ** keys, the VDBE layer invokes sqlite3BtreeLast() to figure out the 
  ** integer key to use. It then calls this function to actually insert the 
  ** data into the intkey B-Tree. In this case btreeMoveto() recognizes
  ** that the cursor is already where it needs to be and returns without
  ** doing any work. To avoid thwarting these optimizations, it is important
  ** not to clear the cursor here.
  */
  rc = saveAllCursors(pBt, pCur->pgnoRoot, pCur);
  if( rc ) return rc;

  /* If this is an insert into a table b-tree, invalidate any incrblob 
  ** cursors open on the row being replaced (assuming this is a replace
  ** operation - if it is not, the following is a no-op).  */
  if( pCur->pKeyInfo==0 ){
    invalidateIncrblobCursors(p, nKey, 0);
  }

  if( !loc ){
    rc = btreeMoveto(pCur, pKey, nKey, appendBias, &loc);
    if( rc ) return rc;
  }
  assert( pCur->eState==CURSOR_VALID || (pCur->eState==CURSOR_INVALID && loc) );

  pPage = pCur->apPage[pCur->iPage];
................................................................................

  if( NEVER(pCur->aiIdx[pCur->iPage]>=pCur->apPage[pCur->iPage]->nCell) 
   || NEVER(pCur->eState!=CURSOR_VALID)
  ){
    return SQLITE_ERROR;  /* Something has gone awry. */
  }







  iCellDepth = pCur->iPage;
  iCellIdx = pCur->aiIdx[iCellDepth];
  pPage = pCur->apPage[iCellDepth];
  pCell = findCell(pPage, iCellIdx);

  /* If the page containing the entry to delete is not a leaf page, move
  ** the cursor to the largest entry in the tree that is smaller than
................................................................................
  /* Save the positions of any other cursors open on this table before
  ** making any modifications. Make the page containing the entry to be 
  ** deleted writable. Then free any overflow pages associated with the 
  ** entry and finally remove the cell itself from within the page.  
  */
  rc = saveAllCursors(pBt, pCur->pgnoRoot, pCur);
  if( rc ) return rc;

  /* If this is a delete operation to remove a row from a table b-tree,
  ** invalidate any incrblob cursors open on the row being deleted.  */
  if( pCur->pKeyInfo==0 ){
    invalidateIncrblobCursors(p, pCur->info.nKey, 0);
  }

  rc = sqlite3PagerWrite(pPage->pDbPage);
  if( rc ) return rc;
  rc = clearCell(pPage, pCell);
  dropCell(pPage, iCellIdx, cellSizePtr(pPage, pCell), &rc);
  if( rc ) return rc;

  /* If the cell deleted was not located on a leaf page, then the cursor
................................................................................
*/
int sqlite3BtreeClearTable(Btree *p, int iTable, int *pnChange){
  int rc;
  BtShared *pBt = p->pBt;
  sqlite3BtreeEnter(p);
  assert( p->inTrans==TRANS_WRITE );

  rc = saveAllCursors(pBt, (Pgno)iTable, 0);

  if( SQLITE_OK==rc ){
    /* Invalidate all incrblob cursors open on table iTable (assuming iTable
    ** is the root of a table b-tree - if it is not, the following call is
    ** a no-op).  */
    invalidateIncrblobCursors(p, 0, 1);



    rc = clearDatabasePage(pBt, (Pgno)iTable, 0, pnChange);
  }
  sqlite3BtreeLeave(p);
  return rc;
}

/*

Added test/incrblob4.test.





















































































































































































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# 2012 March 23
#
# 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
ifcapable {!incrblob} { finish_test ; return }
set testprefix incrblob4

proc create_t1 {} {
  execsql {
    PRAGMA page_size = 1024;
    CREATE TABLE t1(k INTEGER PRIMARY KEY, v);
  }
}

proc populate_t1 {} {
  set data [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]
  foreach d $data {
    set blob [string repeat $d 900]
    execsql { INSERT INTO t1(v) VALUES($blob) }
  }
}


do_test 1.1 { 
  create_t1
  populate_t1 
} {}

do_test 1.2 {
  set blob [db incrblob t1 v 5]
  read $blob 10
} {eeeeeeeeee}

do_test 1.3 {
  execsql { DELETE FROM t1 }
  populate_t1
} {}



do_test 2.1 { 
  reset_db
  create_t1
  populate_t1 
} {}

do_test 2.2 {
  set blob [db incrblob t1 v 10]
  read $blob 10
} {jjjjjjjjjj}

do_test 2.3 {
  set new [string repeat % 900]
  execsql { DELETE FROM t1 WHERE k=10 }
  execsql { DELETE FROM t1 WHERE k=9 }
  execsql { INSERT INTO t1(v) VALUES($new) }
} {}



do_test 3.1 {
  reset_db
  create_t1
  populate_t1 
} {}

do_test 3.2 {
  set blob [db incrblob t1 v 20]
  read $blob 10
} {tttttttttt}

do_test 3.3 {
  set new [string repeat % 900]
  execsql { UPDATE t1 SET v = $new WHERE k = 20 }
  execsql { DELETE FROM t1 WHERE k=19 }
  execsql { INSERT INTO t1(v) VALUES($new) }
} {}

finish_test