Experimental change to use a single-pass approach for DELETE statements on non-virtual tables that do not fire triggers or require foriegn-key processing.

FossilOrigin-Name: eaeb2b80f6f8f83679c8323a81bb39570ec946fe

manifest

@@ -1,5 +1,5 @@
-C Import\scommon\schanges\sfrom\sthe\smutex\sinitialization\sbranch.
+C Experimental\schange\sto\suse\sa\ssingle-pass\sapproach\sfor\sDELETE\sstatements\son\snon-virtual\stables\sthat\sdo\snot\sfire\striggers\sor\srequire\sforiegn-key\sprocessing.
-D 2015-09-12T18:57:45.818
+D 2015-09-12T19:26:11.066
 F Makefile.arm-wince-mingw32ce-gcc d6df77f1f48d690bd73162294bbba7f59507c72f
 F Makefile.in f85066ce844a28b671aaeeff320921cd0ce36239
 F Makefile.linux-gcc 91d710bdc4998cb015f39edf3cb314ec4f4d7e23
@@ -282,8 +282,8 @@ F src/auth.c b56c78ebe40a2110fd361379f7e8162d23f92240
 F src/backup.c 4d9134dc988a87838c06056c89c0e8c4700a0452
 F src/bitvec.c d1f21d7d91690747881f03940584f4cc548c9d3d
 F src/btmutex.c 45a968cc85afed9b5e6cf55bf1f42f8d18107f79
-F src/btree.c 4084d9eed2817331f6e6a82230ba30e448cad497
+F src/btree.c 38ed0262d1c66d21bb084f086650e6106ae43d98
-F src/btree.h 969adc948e89e449220ff0ff724c94bb2a52e9f1
+F src/btree.h 40189aefdc2b830d25c8b58fd7d56538481bfdd7
 F src/btreeInt.h 8177c9ab90d772d6d2c6c517e05bed774b7c92c0
 F src/build.c f81380bc4d5d239c18b42982a9866a94489fd444
 F src/callback.c 7b44ce59674338ad48b0e84e7b72f935ea4f68b0
@@ -291,7 +291,7 @@ F src/complete.c addcd8160b081131005d5bc2d34adf20c1c5c92f
 F src/ctime.c 5a0b735dc95604766f5dac73973658eef782ee8b
 F src/date.c fb1c99172017dcc8e237339132c91a21a0788584
 F src/dbstat.c e637e7a7ff40ef32132a418c6fdf1cfb63aa27c7
-F src/delete.c 6792c80d7fb54c4df9f7680413952600e7439492
+F src/delete.c d5a2dc4a4663225abbcab042478dc37a5749b7d7
 F src/expr.c 3a76afcdac925294c39903b7002ddb9e5fd29863
 F src/fault.c 160a0c015b6c2629d3899ed2daf63d75754a32bb
 F src/fkey.c 83e1baba999bed3144ea5a2143fc922edf51135f
@@ -300,7 +300,7 @@ F src/global.c 508e4087f7b41d688e4762dcf4d4fe28cfbc87f9
 F src/hash.c 4263fbc955f26c2e8cdc0cf214bc42435aa4e4f5
 F src/hash.h c8f3c31722cf3277d03713909761e152a5b81094
 F src/hwtime.h d32741c8f4df852c7d959236615444e2b1063b08
-F src/insert.c 076dc5876e261a9908603d54cfc5344cd680166c
+F src/insert.c db8a34cf8ba600ac1cebb3c03e93c92154d0fc4c
 F src/journal.c b4124532212b6952f42eb2c12fa3c25701d8ba8d
 F src/legacy.c ba1863ea58c4c840335a84ec276fc2b25e22bc4e
 F src/lempar.c d344a95d60c24e2f490ee59db9784b1b17439012
@@ -345,7 +345,7 @@ F src/shell.c 6332ef06db1390ef812cfdff1fc97b4fd76cdd42
 F src/sqlite.h.in dbaf8c3796e80221de4395b5f4f872abddb5f89f
 F src/sqlite3.rc 992c9f5fb8285ae285d6be28240a7e8d3a7f2bad
 F src/sqlite3ext.h 64350bf36833a56ad675e27392a913f417c5c308
-F src/sqliteInt.h b3e590f374b376a793b93e2387b8d5aca0fc92c4
+F src/sqliteInt.h 91bf09de55402157d1476a61df46ef6cfbc0bbc3
 F src/sqliteLimit.h 216557999cb45f2e3578ed53ebefe228d779cb46
 F src/status.c f266ad8a2892d659b74f0f50cb6a88b6e7c12179
 F src/table.c 51b46b2a62d1b3a959633d593b89bab5e2c9155e
@@ -399,11 +399,11 @@ F src/threads.c 6bbcc9fe50c917864d48287b4792d46d6e873481
 F src/tokenize.c 83c6ed569423a3af83a83973b444cf7123be33a6
 F src/treeview.c 154f0acc622fa3514de8777dcedf4c8a8802b4ce
 F src/trigger.c 322f23aad694e8f31d384dcfa386d52a48d3c52f
-F src/update.c 3c5bc9570df3bfafa0db36828406a8a14e4c426e
+F src/update.c eb7ab3ff2928628692a4f14be397c95f4a681d97
 F src/utf.c fc6b889ba0779b7722634cdeaa25f1930d93820c
 F src/util.c fc612367108b74573c5fd13a85d0a23027f438bd
 F src/vacuum.c 2ddd5cad2a7b9cef7f9e431b8c7771634c6b1701
-F src/vdbe.c 6d85be995bd2308a5aa2a68c7b564c5d4cc1a6fb
+F src/vdbe.c 5587d76bd5a4fb4f7ca023f161a6c6adbb1de26c
 F src/vdbe.h 4bc88bd0e06f8046ee6ab7487c0015e85ad949ad
 F src/vdbeInt.h 8b867eac234e28627ffcace3cd4b4b79bbec664b
 F src/vdbeapi.c 0d890f57caf143b114a95ce699e59af51359c508
@@ -417,7 +417,7 @@ F src/vxworks.h c18586c8edc1bddbc15c004fa16aeb1e1342b4fb
 F src/wal.c 18b0ed49830cf04fe2d68224b41838a73ac6cd24
 F src/wal.h df01efe09c5cb8c8e391ff1715cca294f89668a4
 F src/walker.c 2e14d17f592d176b6dc879c33fbdec4fbccaa2ba
-F src/where.c 1227687e7892d4009f3c3433e974eb9c9e3c4d6a
+F src/where.c 98cbedead64380fc26a098350f43d92237c8fa17
 F src/whereInt.h 292d3ac90da4eab1e03ac8452f1add746bcafaa1
 F src/wherecode.c 6ac8599523f4840d9efac335329f627ebf3f79fd
 F src/whereexpr.c 2473e4350e30f9b55d1c6a8f66ca23c689f23f1d
@@ -569,9 +569,10 @@ F test/date.test 42973251b9429f2c41b77eb98a7b0b0ba2d3b2c0
 F test/dbstatus.test 8de104bb5606f19537d23cd553b41349b5ab1204
 F test/dbstatus2.test 10418e62b3db5dca070f0c3eef3ea13946f339c2
 F test/default.test 0cb49b1c315a0d81c81d775e407f66906a2a604d
-F test/delete.test a065b05d2ebf60fd16639c579a4adfb7c381c701
+F test/delete.test e1bcdf8926234e27aac24b346ad83d3329ec8b6f
 F test/delete2.test 3a03f2cca1f9a67ec469915cb8babd6485db43fa
 F test/delete3.test 555e84a00a99230b7d049d477a324a631126a6ab
+F test/delete4.test d9e7d553a939597b27d205b022d769469f361c1f
 F test/descidx1.test 6d03b44c8538fe0eb4924e19fba10cdd8f3c9240
 F test/descidx2.test 9f1a0c83fd57f8667c82310ca21b30a350888b5d
 F test/descidx3.test 09ddbe3f5295f482d2f8b687cf6db8bad7acd9a2
@@ -782,7 +783,7 @@ F test/index4.test ab92e736d5946840236cd61ac3191f91a7856bf6
 F test/index5.test 8621491915800ec274609e42e02a97d67e9b13e7
 F test/index6.test 7102ec371414c42dfb1d5ca37eb4519aa9edc23a
 F test/index7.test 9c6765a74fc3fcde7aebc5b3bd40d98df14a527c
-F test/indexedby.test 69d2292dfdabe85aa7c5df577c71bb4325607ec2
+F test/indexedby.test 9c4cd331224e57f79fbf411ae245e6272d415985
 F test/indexexpr1.test 4feec154aadacb033b41acc1760a18edc4c60470
 F test/indexfault.test 31d4ab9a7d2f6e9616933eb079722362a883eb1d
 F test/init.test 15c823093fdabbf7b531fe22cf037134d09587a7
@@ -1386,7 +1387,10 @@ F tool/vdbe_profile.tcl 67746953071a9f8f2f668b73fe899074e2c6d8c1
 F tool/warnings-clang.sh f6aa929dc20ef1f856af04a730772f59283631d4
 F tool/warnings.sh 48bd54594752d5be3337f12c72f28d2080cb630b
 F tool/win/sqlite.vsix deb315d026cc8400325c5863eef847784a219a2f
-P 86781093bdb4c4fdedd228cb1c8961db48a483bb
+P 334720c01722478af0d3dfd6fe8bafd88ba09f49
-R 65cef7a212785e2c4ed01bbc55ee07c1
+R 7f7d9f32d96ad1f6004a92150fc6799e
-U mistachkin
+T *branch * onepass-delete
-Z 122b4ea017ab904cde327a85d32df791
+T *sym-onepass-delete *
+T -sym-trunk *
+U dan
+Z 9a0d15a0b8fdf4a99fe6f2640c27db22

manifest.uuid

@@ -1 +1 @@
-334720c01722478af0d3dfd6fe8bafd88ba09f49
+eaeb2b80f6f8f83679c8323a81bb39570ec946fe

src/btree.c

@@ -591,6 +591,49 @@ static void btreeReleaseAllCursorPages(BtCursor *pCur){
   pCur->iPage = -1;
 }
 
+/*
+** The cursor passed as the only argument must point to a valid entry
+** when this function is called (i.e. have eState==CURSOR_VALID). This
+** function saves the current cursor key in variables pCur->nKey and
+** pCur->pKey. SQLITE_OK is returned if successful or an SQLite error 
+** code otherwise.
+**
+** If the cursor is open on an intkey table, then the integer key
+** (the rowid) is stored in pCur->nKey and pCur->pKey is left set to
+** NULL. If the cursor is open on a non-intkey table, then pCur->pKey is 
+** set to point to a malloced buffer pCur->nKey bytes in size containing 
+** the key.
+*/
+static int saveCursorKey(BtCursor *pCur){
+  int rc;
+  assert( CURSOR_VALID==pCur->eState );
+  assert( 0==pCur->pKey );
+  assert( cursorHoldsMutex(pCur) );
+
+  rc = sqlite3BtreeKeySize(pCur, &pCur->nKey);
+  assert( rc==SQLITE_OK );  /* KeySize() cannot fail */
+
+  /* If this is an intKey table, then the above call to BtreeKeySize()
+  ** stores the integer key in pCur->nKey. In this case this value is
+  ** all that is required. Otherwise, if pCur is not open on an intKey
+  ** table, then malloc space for and store the pCur->nKey bytes of key 
+  ** data.  */
+  if( 0==pCur->curIntKey ){
+    void *pKey = sqlite3Malloc( pCur->nKey );
+    if( pKey ){
+      rc = sqlite3BtreeKey(pCur, 0, (int)pCur->nKey, pKey);
+      if( rc==SQLITE_OK ){
+        pCur->pKey = pKey;
+      }else{
+        sqlite3_free(pKey);
+      }
+    }else{
+      rc = SQLITE_NOMEM;
+    }
+  }
+  assert( !pCur->curIntKey || !pCur->pKey );
+  return rc;
+}
 
 /*
 ** Save the current cursor position in the variables BtCursor.nKey 
@@ -611,30 +654,8 @@ static int saveCursorPosition(BtCursor *pCur){
   }else{
     pCur->skipNext = 0;
   }
-  rc = sqlite3BtreeKeySize(pCur, &pCur->nKey);
-  assert( rc==SQLITE_OK );  /* KeySize() cannot fail */
-
-  /* If this is an intKey table, then the above call to BtreeKeySize()
-  ** stores the integer key in pCur->nKey. In this case this value is
-  ** all that is required. Otherwise, if pCur is not open on an intKey
-  ** table, then malloc space for and store the pCur->nKey bytes of key 
-  ** data.
-  */
-  if( 0==pCur->curIntKey ){
-    void *pKey = sqlite3Malloc( pCur->nKey );
-    if( pKey ){
-      rc = sqlite3BtreeKey(pCur, 0, (int)pCur->nKey, pKey);
-      if( rc==SQLITE_OK ){
-        pCur->pKey = pKey;
-      }else{
-        sqlite3_free(pKey);
-      }
-    }else{
-      rc = SQLITE_NOMEM;
-    }
-  }
-  assert( !pCur->curIntKey || !pCur->pKey );
 
+  rc = saveCursorKey(pCur);
   if( rc==SQLITE_OK ){
     btreeReleaseAllCursorPages(pCur);
     pCur->eState = CURSOR_REQUIRESEEK;
@@ -8026,10 +8047,15 @@ end_insert:
 }
 
 /*
-** Delete the entry that the cursor is pointing to.  The cursor
+** Delete the entry that the cursor is pointing to. 
-** is left pointing at an arbitrary location.
+**
+** If the second parameter is zero, then the cursor is left pointing at an
+** arbitrary location after the delete. If it is non-zero, then the cursor 
+** is left in a state such that the next call to BtreeNext() or BtreePrev()
+** moves it to the same row as it would if the call to BtreeDelete() had
+** been omitted.
 */
-int sqlite3BtreeDelete(BtCursor *pCur){
+int sqlite3BtreeDelete(BtCursor *pCur, int bPreserve){
   Btree *p = pCur->pBtree;
   BtShared *pBt = p->pBt;              
   int rc;                              /* Return code */
@@ -8038,6 +8064,7 @@ int sqlite3BtreeDelete(BtCursor *pCur){
   int iCellIdx;                        /* Index of cell to delete */
   int iCellDepth;                      /* Depth of node containing pCell */ 
   u16 szCell;                          /* Size of the cell being deleted */
+  int bSkipnext = 0;                   /* Leaf cursor in SKIPNEXT state */
 
   assert( cursorHoldsMutex(pCur) );
   assert( pBt->inTransaction==TRANS_WRITE );
@@ -8067,10 +8094,7 @@ int sqlite3BtreeDelete(BtCursor *pCur){
   }
 
   /* Save the positions of any other cursors open on this table before
-  ** making any modifications. Make the page containing the entry to be 
+  ** making any modifications.  */
-  ** deleted writable. Then free any overflow pages associated with the 
-  ** entry and finally remove the cell itself from within the page.  
-  */
   if( pCur->curFlags & BTCF_Multiple ){
     rc = saveAllCursors(pBt, pCur->pgnoRoot, pCur);
     if( rc ) return rc;
@@ -8082,6 +8106,31 @@ int sqlite3BtreeDelete(BtCursor *pCur){
     invalidateIncrblobCursors(p, pCur->info.nKey, 0);
   }
 
+  /* If the bPreserve flag is set to true, then the cursor position must
+  ** be preserved following this delete operation. If the current delete
+  ** will cause a b-tree rebalance, then this is done by saving the cursor
+  ** key and leaving the cursor in CURSOR_REQUIRESEEK state before 
+  ** returning. 
+  **
+  ** Or, if the current delete will not cause a rebalance, then the cursor
+  ** will be left in CURSOR_SKIPNEXT state pointing to the entry immediately
+  ** before or after the deleted entry. In this case set bSkipnext to true.  */
+  if( bPreserve ){
+    if( !pPage->leaf 
+     || (pPage->nFree + cellSizePtr(pPage, pCell) + 2)>(pBt->usableSize*2/3)
+    ){
+      /* A b-tree rebalance will be required after deleting this entry.
+      ** Save the cursor key.  */
+      rc = saveCursorKey(pCur);
+      if( rc ) return rc;
+    }else{
+      bSkipnext = 1;
+    }
+  }
+
+  /* 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 = sqlite3PagerWrite(pPage->pDbPage);
   if( rc ) return rc;
   rc = clearCell(pPage, pCell, &szCell);
@@ -8135,7 +8184,22 @@ int sqlite3BtreeDelete(BtCursor *pCur){
   }
 
   if( rc==SQLITE_OK ){
-    moveToRoot(pCur);
+    if( bSkipnext ){
+      assert( bPreserve && pCur->iPage==iCellDepth );
+      assert( pPage->nCell>0 && iCellIdx<=pPage->nCell );
+      pCur->eState = CURSOR_SKIPNEXT;
+      if( iCellIdx>=pPage->nCell ){
+        pCur->skipNext = -1;
+        pCur->aiIdx[iCellDepth] = pPage->nCell-1;
+      }else{
+        pCur->skipNext = 1;
+      }
+    }else{
+      rc = moveToRoot(pCur);
+      if( bPreserve ){
+        pCur->eState = CURSOR_REQUIRESEEK;
+      }
+    }
   }
   return rc;
 }

src/btree.h

@@ -185,7 +185,7 @@ int sqlite3BtreeMovetoUnpacked(
 );
 int sqlite3BtreeCursorHasMoved(BtCursor*);
 int sqlite3BtreeCursorRestore(BtCursor*, int*);
-int sqlite3BtreeDelete(BtCursor*);
+int sqlite3BtreeDelete(BtCursor*, int);
 int sqlite3BtreeInsert(BtCursor*, const void *pKey, i64 nKey,
                                   const void *pData, int nData,
                                   int nZero, int bias, int seekResult);

src/delete.c

@@ -235,7 +235,7 @@ void sqlite3DeleteFrom(
   int iDb;               /* Database number */
   int memCnt = -1;       /* Memory cell used for change counting */
   int rcauth;            /* Value returned by authorization callback */
-  int okOnePass;         /* True for one-pass algorithm without the FIFO */
+  int eOnePass;          /* Non-zero for one-pass algorithm without the FIFO */
   int aiCurOnePass[2];   /* The write cursors opened by WHERE_ONEPASS */
   u8 *aToOpen = 0;       /* Open cursor iTabCur+j if aToOpen[j] is true */
   Index *pPk;            /* The PRIMARY KEY index on the table */
@@ -253,6 +253,7 @@ void sqlite3DeleteFrom(
 #ifndef SQLITE_OMIT_TRIGGER
   int isView;                  /* True if attempting to delete from a view */
   Trigger *pTrigger;           /* List of table triggers, if required */
+  int bComplex;                /* True if there are either triggers or FKs */
 #endif
 
   memset(&sContext, 0, sizeof(sContext));
@@ -276,9 +277,11 @@ void sqlite3DeleteFrom(
 #ifndef SQLITE_OMIT_TRIGGER
   pTrigger = sqlite3TriggersExist(pParse, pTab, TK_DELETE, 0, 0);
   isView = pTab->pSelect!=0;
+  bComplex = pTrigger || sqlite3FkRequired(pParse, pTab, 0, 0);
 #else
 # define pTrigger 0
 # define isView 0
+# define bComplex 0
 #endif
 #ifdef SQLITE_OMIT_VIEW
 # undef isView
@@ -359,9 +362,7 @@ void sqlite3DeleteFrom(
   ** It is easier just to erase the whole table. Prior to version 3.6.5,
   ** this optimization caused the row change count (the value returned by 
   ** API function sqlite3_count_changes) to be set incorrectly.  */
-  if( rcauth==SQLITE_OK && pWhere==0 && !pTrigger && !IsVirtual(pTab) 
+  if( rcauth==SQLITE_OK && pWhere==0 && !bComplex && !IsVirtual(pTab) ){
-   && 0==sqlite3FkRequired(pParse, pTab, 0, 0)
-  ){
     assert( !isView );
     sqlite3TableLock(pParse, iDb, pTab->tnum, 1, pTab->zName);
     if( HasRowid(pTab) ){
@@ -375,6 +376,8 @@ void sqlite3DeleteFrom(
   }else
 #endif /* SQLITE_OMIT_TRUNCATE_OPTIMIZATION */
   {
+    u16 wcf = WHERE_ONEPASS_DESIRED|WHERE_DUPLICATES_OK;
+    wcf |= (bComplex ? 0 : WHERE_ONEPASS_MULTIROW);
     if( HasRowid(pTab) ){
       /* For a rowid table, initialize the RowSet to an empty set */
       pPk = 0;
@@ -395,13 +398,17 @@ void sqlite3DeleteFrom(
     }
   
     /* Construct a query to find the rowid or primary key for every row
-    ** to be deleted, based on the WHERE clause.
+    ** to be deleted, based on the WHERE clause. Set variable eOnePass
+    ** to indicate the strategy used to implement this delete:
+    **
+    **   0: Two-pass approach - use a FIFO for rowids/PK values.
+    **   1: One-pass approach - at most one row deleted.
+    **   2: One-pass approach - any number of rows may be deleted.
     */
-    pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, 0, 0, 
+    pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, 0, 0, wcf, iTabCur+1);
-                               WHERE_ONEPASS_DESIRED|WHERE_DUPLICATES_OK,
-                               iTabCur+1);
     if( pWInfo==0 ) goto delete_from_cleanup;
-    okOnePass = sqlite3WhereOkOnePass(pWInfo, aiCurOnePass);
+    eOnePass = sqlite3WhereOkOnePass(pWInfo, aiCurOnePass);
+    assert( IsVirtual(pTab)==0 || eOnePass==0 );
   
     /* Keep track of the number of rows to be deleted */
     if( db->flags & SQLITE_CountRows ){
@@ -422,11 +429,10 @@ void sqlite3DeleteFrom(
       if( iKey>pParse->nMem ) pParse->nMem = iKey;
     }
   
-    if( okOnePass ){
+    if( eOnePass ){
       /* For ONEPASS, no need to store the rowid/primary-key. There is only
       ** one, so just keep it in its register(s) and fall through to the
-      ** delete code.
+      ** delete code.  */
-      */
       nKey = nPk; /* OP_Found will use an unpacked key */
       aToOpen = sqlite3DbMallocRaw(db, nIdx+2);
       if( aToOpen==0 ){
@@ -438,27 +444,27 @@ void sqlite3DeleteFrom(
       if( aiCurOnePass[0]>=0 ) aToOpen[aiCurOnePass[0]-iTabCur] = 0;
       if( aiCurOnePass[1]>=0 ) aToOpen[aiCurOnePass[1]-iTabCur] = 0;
       if( addrEphOpen ) sqlite3VdbeChangeToNoop(v, addrEphOpen);
-      addrDelete = sqlite3VdbeAddOp0(v, OP_Goto); /* Jump to DELETE logic */
+    }else{
-    }else if( pPk ){
+      if( pPk ){
-      /* Construct a composite key for the row to be deleted and remember it */
+        /* Add the PK key for this row to the temporary table */
         iKey = ++pParse->nMem;
         nKey = 0;   /* Zero tells OP_Found to use a composite key */
         sqlite3VdbeAddOp4(v, OP_MakeRecord, iPk, nPk, iKey,
             sqlite3IndexAffinityStr(pParse->db, pPk), nPk);
         sqlite3VdbeAddOp2(v, OP_IdxInsert, iEphCur, iKey);
       }else{
-      /* Get the rowid of the row to be deleted and remember it in the RowSet */
+        /* Add the rowid of the row to be deleted to the RowSet */
         nKey = 1;  /* OP_Seek always uses a single rowid */
         sqlite3VdbeAddOp2(v, OP_RowSetAdd, iRowSet, iKey);
       }
+    }
   
-    /* End of the WHERE loop */
+    /* If this DELETE cannot use the ONEPASS strategy, this is the 
-    sqlite3WhereEnd(pWInfo);
+    ** end of the WHERE loop */
-    if( okOnePass ){
+    if( eOnePass ){
-      /* Bypass the delete logic below if the WHERE loop found zero rows */
       addrBypass = sqlite3VdbeMakeLabel(v);
-      sqlite3VdbeGoto(v, addrBypass);
+    }else{
-      sqlite3VdbeJumpHere(v, addrDelete);
+      sqlite3WhereEnd(pWInfo);
     }
   
     /* Unless this is a view, open cursors for the table we are 
@@ -467,20 +473,21 @@ void sqlite3DeleteFrom(
     ** triggers.
     */
     if( !isView ){
+      int iAddrOnce;
+      if( eOnePass==2 ) iAddrOnce = sqlite3CodeOnce(pParse);
       testcase( IsVirtual(pTab) );
       sqlite3OpenTableAndIndices(pParse, pTab, OP_OpenWrite, iTabCur, aToOpen,
                                  &iDataCur, &iIdxCur);
       assert( pPk || IsVirtual(pTab) || iDataCur==iTabCur );
       assert( pPk || IsVirtual(pTab) || iIdxCur==iDataCur+1 );
+      if( eOnePass==2 ) sqlite3VdbeJumpHere(v, iAddrOnce);
     }
   
     /* Set up a loop over the rowids/primary-keys that were found in the
     ** where-clause loop above.
     */
-    if( okOnePass ){
+    if( eOnePass ){
-      /* Just one row.  Hence the top-of-loop is a no-op */
       assert( nKey==nPk );  /* OP_Found will use an unpacked key */
-      assert( !IsVirtual(pTab) );
       if( aToOpen[iDataCur-iTabCur] ){
         assert( pPk!=0 || pTab->pSelect!=0 );
         sqlite3VdbeAddOp4Int(v, OP_NotFound, iDataCur, addrBypass, iKey, nKey);
@@ -508,13 +515,18 @@ void sqlite3DeleteFrom(
 #endif
     {
       int count = (pParse->nested==0);    /* True to count changes */
+      int iIdxNoSeek = -1;
+      if( bComplex==0 && aiCurOnePass[1]!=iDataCur ){
+        iIdxNoSeek = aiCurOnePass[1];
+      }
       sqlite3GenerateRowDelete(pParse, pTab, pTrigger, iDataCur, iIdxCur,
-                               iKey, nKey, count, OE_Default, okOnePass);
+          iKey, nKey, count, OE_Default, eOnePass, iIdxNoSeek);
     }
   
     /* End of the loop over all rowids/primary-keys. */
-    if( okOnePass ){
+    if( eOnePass ){
       sqlite3VdbeResolveLabel(v, addrBypass);
+      sqlite3WhereEnd(pWInfo);
     }else if( pPk ){
       sqlite3VdbeAddOp2(v, OP_Next, iEphCur, addrLoop+1); VdbeCoverage(v);
       sqlite3VdbeJumpHere(v, addrLoop);
@@ -586,6 +598,25 @@ delete_from_cleanup:
 **       sequence of nPk memory cells starting at iPk.  If nPk==0 that means
 **       that a search record formed from OP_MakeRecord is contained in the
 **       single memory location iPk.
+**
+** eMode:
+**   Parameter eMode may be passed either 0, 1 or 2. If it is passed a 
+**   non-zero value, then it is guaranteed that cursor iDataCur already 
+**   points to the row to delete. If it is passed 0, then this function 
+**   must seek iDataCur to the entry identified by iPk and nPk before
+**   reading from it.
+**
+**   If eMode is passed the value 2, then this call is being made as part
+**   of a ONEPASS delete that affects multiple rows. In this case, if 
+**   iIdxNoSeek is a valid cursor number (>=0), then its position should
+**   be preserved following the delete operation. Or, if iIdxNoSeek is not
+**   a valid cursor number, the position of iDataCur should be preserved
+**   instead.
+**
+** iIdxNoSeek:
+**   If iIdxNoSeek is a valid cursor number (>=0), then it identifies an
+**   index cursor (from within array of cursors starting at iIdxCur) that
+**   already points to the index entry to be deleted.
 */
 void sqlite3GenerateRowDelete(
   Parse *pParse,     /* Parsing context */
@@ -597,7 +628,8 @@ void sqlite3GenerateRowDelete(
   i16 nPk,           /* Number of PRIMARY KEY memory cells */
   u8 count,          /* If non-zero, increment the row change counter */
   u8 onconf,         /* Default ON CONFLICT policy for triggers */
-  u8 bNoSeek         /* iDataCur is already pointing to the row to delete */
+  u8 eMode,          /* See explanation above */
+  int iIdxNoSeek     /* Cursor number of cursor that does not need seeking */
 ){
   Vdbe *v = pParse->pVdbe;        /* Vdbe */
   int iOld = 0;                   /* First register in OLD.* array */
@@ -614,7 +646,7 @@ void sqlite3GenerateRowDelete(
   ** not attempt to delete it or fire any DELETE triggers.  */
   iLabel = sqlite3VdbeMakeLabel(v);
   opSeek = HasRowid(pTab) ? OP_NotExists : OP_NotFound;
-  if( !bNoSeek ){
+  if( eMode==0 ){
     sqlite3VdbeAddOp4Int(v, opSeek, iDataCur, iLabel, iPk, nPk);
     VdbeCoverageIf(v, opSeek==OP_NotExists);
     VdbeCoverageIf(v, opSeek==OP_NotFound);
@@ -674,11 +706,15 @@ void sqlite3GenerateRowDelete(
   ** a view (in which case the only effect of the DELETE statement is to
   ** fire the INSTEAD OF triggers).  */ 
   if( pTab->pSelect==0 ){
-    sqlite3GenerateRowIndexDelete(pParse, pTab, iDataCur, iIdxCur, 0);
+    sqlite3GenerateRowIndexDelete(pParse, pTab, iDataCur, iIdxCur,0,iIdxNoSeek);
     sqlite3VdbeAddOp2(v, OP_Delete, iDataCur, (count?OPFLAG_NCHANGE:0));
     if( count ){
       sqlite3VdbeChangeP4(v, -1, pTab->zName, P4_TRANSIENT);
     }
+    if( iIdxNoSeek>=0 ){
+      sqlite3VdbeAddOp1(v, OP_Delete, iIdxNoSeek);
+    }
+    sqlite3VdbeChangeP5(v, eMode==2);
   }
 
   /* Do any ON CASCADE, SET NULL or SET DEFAULT operations required to
@@ -721,7 +757,8 @@ void sqlite3GenerateRowIndexDelete(
   Table *pTab,       /* Table containing the row to be deleted */
   int iDataCur,      /* Cursor of table holding data. */
   int iIdxCur,       /* First index cursor */
-  int *aRegIdx       /* Only delete if aRegIdx!=0 && aRegIdx[i]>0 */
+  int *aRegIdx,      /* Only delete if aRegIdx!=0 && aRegIdx[i]>0 */
+  int iIdxNoSeek     /* Do not delete from this cursor */
 ){
   int i;             /* Index loop counter */
   int r1 = -1;       /* Register holding an index key */
@@ -737,6 +774,7 @@ void sqlite3GenerateRowIndexDelete(
     assert( iIdxCur+i!=iDataCur || pPk==pIdx );
     if( aRegIdx!=0 && aRegIdx[i]==0 ) continue;
     if( pIdx==pPk ) continue;
+    if( iIdxCur+i==iIdxNoSeek ) continue;
     VdbeModuleComment((v, "GenRowIdxDel for %s", pIdx->zName));
     r1 = sqlite3GenerateIndexKey(pParse, pIdx, iDataCur, 0, 1,
         &iPartIdxLabel, pPrior, r1);

src/insert.c

@@ -1347,10 +1347,10 @@ void sqlite3GenerateConstraintChecks(
         if( pTrigger || sqlite3FkRequired(pParse, pTab, 0, 0) ){
           sqlite3MultiWrite(pParse);
           sqlite3GenerateRowDelete(pParse, pTab, pTrigger, iDataCur, iIdxCur,
-                                   regNewData, 1, 0, OE_Replace, 1);
+                                   regNewData, 1, 0, OE_Replace, 1, -1);
         }else if( pTab->pIndex ){
           sqlite3MultiWrite(pParse);
-          sqlite3GenerateRowIndexDelete(pParse, pTab, iDataCur, iIdxCur, 0);
+          sqlite3GenerateRowIndexDelete(pParse, pTab, iDataCur, iIdxCur, 0, -1);
         }
         seenReplace = 1;
         break;
@@ -1528,7 +1528,7 @@ void sqlite3GenerateConstraintChecks(
           pTrigger = sqlite3TriggersExist(pParse, pTab, TK_DELETE, 0, 0);
         }
         sqlite3GenerateRowDelete(pParse, pTab, pTrigger, iDataCur, iIdxCur,
-                                 regR, nPkField, 0, OE_Replace, pIdx==pPk);
+            regR, nPkField, 0, OE_Replace, pIdx==pPk, -1);
         seenReplace = 1;
         break;
       }

src/sqliteInt.h

@@ -2352,6 +2352,7 @@ struct SrcList {
 #define WHERE_WANT_DISTINCT    0x0400 /* All output needs to be distinct */
 #define WHERE_SORTBYGROUP      0x0800 /* Support sqlite3WhereIsSorted() */
 #define WHERE_REOPEN_IDX       0x1000 /* Try to use OP_ReopenIdx */
+#define WHERE_ONEPASS_MULTIROW 0x2000 /* ONEPASS is ok with multiple rows */
 
 /* Allowed return values from sqlite3WhereIsDistinct()
 */
@@ -3440,8 +3441,9 @@ int sqlite3ExprIsInteger(Expr*, int*);
 int sqlite3ExprCanBeNull(const Expr*);
 int sqlite3ExprNeedsNoAffinityChange(const Expr*, char);
 int sqlite3IsRowid(const char*);
-void sqlite3GenerateRowDelete(Parse*,Table*,Trigger*,int,int,int,i16,u8,u8,u8);
+void sqlite3GenerateRowDelete(
-void sqlite3GenerateRowIndexDelete(Parse*, Table*, int, int, int*);
+    Parse*,Table*,Trigger*,int,int,int,i16,u8,u8,u8,int);
+void sqlite3GenerateRowIndexDelete(Parse*, Table*, int, int, int*, int);
 int sqlite3GenerateIndexKey(Parse*, Index*, int, int, int, int*,Index*,int);
 void sqlite3ResolvePartIdxLabel(Parse*,int);
 void sqlite3GenerateConstraintChecks(Parse*,Table*,int*,int,int,int,int,

src/update.c

@@ -587,7 +587,7 @@ void sqlite3Update(
       }
       VdbeCoverageNeverTaken(v);
     }
-    sqlite3GenerateRowIndexDelete(pParse, pTab, iDataCur, iIdxCur, aRegIdx);
+    sqlite3GenerateRowIndexDelete(pParse, pTab, iDataCur, iIdxCur, aRegIdx, -1);
   
     /* If changing the record number, delete the old record.  */
     if( hasFK || chngKey || pPk!=0 ){

src/vdbe.c

@@ -4274,14 +4274,15 @@ case OP_InsertInt: {
   break;
 }
 
-/* Opcode: Delete P1 P2 * P4 *
+/* Opcode: Delete P1 P2 * P4 P5
 **
 ** Delete the record at which the P1 cursor is currently pointing.
 **
-** The cursor will be left pointing at either the next or the previous
+** If the P5 parameter is non-zero, the cursor will be left pointing at 
-** record in the table. If it is left pointing at the next record, then
+** either the next or the previous record in the table. If it is left 
-** the next Next instruction will be a no-op.  Hence it is OK to delete
+** pointing at the next record, then the next Next instruction will be a 
-** a record from within a Next loop.
+** no-op. As a result, in this case it is OK to delete a record from within a
+** Next loop. If P5 is zero, then the cursor is left in an undefined state.
 **
 ** If the OPFLAG_NCHANGE flag of P2 is set, then the row change count is
 ** incremented (otherwise not).
@@ -4301,20 +4302,26 @@ case OP_Delete: {
   pC = p->apCsr[pOp->p1];
   assert( pC!=0 );
   assert( pC->pCursor!=0 );  /* Only valid for real tables, no pseudotables */
-  assert( pC->deferredMoveto==0 );
+
+  if( pC->deferredMoveto ){
+    rc = sqlite3VdbeCursorMoveto(pC);
+    if( rc!=SQLITE_OK ) goto abort_due_to_error;
+  }else if( pOp->p5 && db->xUpdateCallback && pOp->p4.z && pC->isTable ){
+    sqlite3BtreeKeySize(pC->pCursor, &pC->movetoTarget);
+  }
 
 #ifdef SQLITE_DEBUG
   /* The seek operation that positioned the cursor prior to OP_Delete will
   ** have also set the pC->movetoTarget field to the rowid of the row that
   ** is being deleted */
-  if( pOp->p4.z && pC->isTable ){
+  if( pOp->p4.z && pC->isTable && pOp->p5==0 ){
     i64 iKey = 0;
     sqlite3BtreeKeySize(pC->pCursor, &iKey);
     assert( pC->movetoTarget==iKey ); 
   }
 #endif
  
-  rc = sqlite3BtreeDelete(pC->pCursor);
+  rc = sqlite3BtreeDelete(pC->pCursor, pOp->p5);
   pC->cacheStatus = CACHE_STALE;
 
   /* Invoke the update-hook if required. */
@@ -4857,7 +4864,7 @@ case OP_IdxDelete: {
 #endif
   rc = sqlite3BtreeMovetoUnpacked(pCrsr, &r, 0, 0, &res);
   if( rc==SQLITE_OK && res==0 ){
-    rc = sqlite3BtreeDelete(pCrsr);
+    rc = sqlite3BtreeDelete(pCrsr, 0);
   }
   assert( pC->deferredMoveto==0 );
   pC->cacheStatus = CACHE_STALE;

src/where.c

@@ -3958,6 +3958,10 @@ WhereInfo *sqlite3WhereBegin(
   sqlite3 *db;               /* Database connection */
   int rc;                    /* Return code */
 
+  assert( (wctrlFlags & WHERE_ONEPASS_MULTIROW)==0 || (
+        (wctrlFlags & WHERE_ONEPASS_DESIRED)!=0 
+     && (wctrlFlags & WHERE_OMIT_OPEN_CLOSE)==0 
+  ));
 
   /* Variable initialization */
   db = pParse->db;
@@ -4199,13 +4203,18 @@ WhereInfo *sqlite3WhereBegin(
   ** the statement to update or delete a single row.
   */
   assert( (wctrlFlags & WHERE_ONEPASS_DESIRED)==0 || pWInfo->nLevel==1 );
-  if( (wctrlFlags & WHERE_ONEPASS_DESIRED)!=0 
+  if( (wctrlFlags & WHERE_ONEPASS_DESIRED)!=0 ){
-   && (pWInfo->a[0].pWLoop->wsFlags & WHERE_ONEROW)!=0 ){
+    int wsFlags = pWInfo->a[0].pWLoop->wsFlags;
-    pWInfo->okOnePass = 1;
+    int bOnerow = (wsFlags & WHERE_ONEROW)!=0;
+    if( bOnerow || ( (wctrlFlags & WHERE_ONEPASS_MULTIROW)
+       && 0==(wsFlags & WHERE_VIRTUALTABLE)
+    )){
+      pWInfo->okOnePass = bOnerow ? 1 : 2;
       if( HasRowid(pTabList->a[0].pTab) ){
         pWInfo->a[0].pWLoop->wsFlags &= ~WHERE_IDX_ONLY;
       }
     }
+  }
 
   /* Open all tables in the pTabList and any indices selected for
   ** searching those tables.

test/delete.test

@@ -68,7 +68,6 @@ do_test delete-3.1.7 {
 } {1 2 4 16}
 integrity_check delete-3.2
 
-
 # Semantic errors in the WHERE clause
 #
 do_test delete-4.1 {

test/delete4.test

@@ -0,0 +1,102 @@
+# 2005 August 24
+#
+# 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 of this script is a test of the DELETE command.
+#
+
+set testdir [file dirname $argv0]
+source $testdir/tester.tcl
+set testprefix delete4
+
+do_execsql_test 1.1 {
+  CREATE TABLE t1(x INTEGER PRIMARY KEY, y);
+  INSERT INTO t1 VALUES(1, 0);
+  INSERT INTO t1 VALUES(2, 1);
+  INSERT INTO t1 VALUES(3, 0);
+  INSERT INTO t1 VALUES(4, 1);
+  INSERT INTO t1 VALUES(5, 0);
+  INSERT INTO t1 VALUES(6, 1);
+  INSERT INTO t1 VALUES(7, 0);
+  INSERT INTO t1 VALUES(8, 1);
+}
+do_execsql_test 1.2 {
+  DELETE FROM t1 WHERE y=1;
+}
+do_execsql_test 1.3 {
+  SELECT x FROM t1;
+} {1 3 5 7}
+
+#-------------------------------------------------------------------------
+#
+reset_db
+do_execsql_test 2.1 {
+  CREATE TABLE t1(x INTEGER PRIMARY KEY, y, z);
+  INSERT INTO t1 VALUES(1, 0, randomblob(200));
+  INSERT INTO t1 VALUES(2, 1, randomblob(200));
+  INSERT INTO t1 VALUES(3, 0, randomblob(200));
+  INSERT INTO t1 VALUES(4, 1, randomblob(200));
+  INSERT INTO t1 VALUES(5, 0, randomblob(200));
+  INSERT INTO t1 VALUES(6, 1, randomblob(200));
+  INSERT INTO t1 VALUES(7, 0, randomblob(200));
+  INSERT INTO t1 VALUES(8, 1, randomblob(200));
+}
+do_execsql_test 2.2 {
+  DELETE FROM t1 WHERE y=1;
+}
+do_execsql_test 2.3 {
+  SELECT x FROM t1;
+} {1 3 5 7}
+
+
+#-------------------------------------------------------------------------
+#
+reset_db
+do_execsql_test 3.1 {
+  CREATE TABLE t1(a, b, PRIMARY KEY(a, b)) WITHOUT ROWID;
+  INSERT INTO t1 VALUES(1, 2);
+  INSERT INTO t1 VALUES(2, 4);
+  INSERT INTO t1 VALUES(1, 5);
+  DELETE FROM t1 WHERE a=1;
+  SELECT * FROM t1;
+} {2 4}
+
+#-------------------------------------------------------------------------
+# DELETE statement that uses the OR optimization
+#
+reset_db
+do_execsql_test 3.1 {
+  CREATE TABLE t1(i INTEGER PRIMARY KEY, a, b);
+  CREATE INDEX i1a ON t1(a);
+  CREATE INDEX i1b ON t1(b);
+  INSERT INTO t1 VALUES(1, 'one', 'i');
+  INSERT INTO t1 VALUES(2, 'two', 'ii');
+  INSERT INTO t1 VALUES(3, 'three', 'iii');
+  INSERT INTO t1 VALUES(4, 'four', 'iv');
+  INSERT INTO t1 VALUES(5, 'one', 'i');
+  INSERT INTO t1 VALUES(6, 'two', 'ii');
+  INSERT INTO t1 VALUES(7, 'three', 'iii');
+  INSERT INTO t1 VALUES(8, 'four', 'iv');
+} {}
+
+do_execsql_test 3.2 {
+  DELETE FROM t1 WHERE a='two' OR b='iv';
+}
+
+do_execsql_test 3.3 {
+  SELECT i FROM t1 ORDER BY i;
+} {1 3 5 7}
+
+do_execsql_test 3.4 { 
+  PRAGMA integrity_check; 
+} {ok}
+
+
+finish_test

test/indexedby.test

@@ -231,13 +231,13 @@ do_execsql_test indexedby-6.2 {
 # 
 do_execsql_test indexedby-7.1 {
   EXPLAIN QUERY PLAN DELETE FROM t1 WHERE a = 5 
-} {0 0 0 {SEARCH TABLE t1 USING COVERING INDEX i1 (a=?)}}
+} {0 0 0 {SEARCH TABLE t1 USING INDEX i1 (a=?)}}
 do_execsql_test indexedby-7.2 {
   EXPLAIN QUERY PLAN DELETE FROM t1 NOT INDEXED WHERE a = 5 
 } {0 0 0 {SCAN TABLE t1}}
 do_execsql_test indexedby-7.3 {
   EXPLAIN QUERY PLAN DELETE FROM t1 INDEXED BY i1 WHERE a = 5 
-} {0 0 0 {SEARCH TABLE t1 USING COVERING INDEX i1 (a=?)}}
+} {0 0 0 {SEARCH TABLE t1 USING INDEX i1 (a=?)}}
 do_execsql_test indexedby-7.4 {
   EXPLAIN QUERY PLAN DELETE FROM t1 INDEXED BY i1 WHERE a = 5 AND b = 10
 } {0 0 0 {SEARCH TABLE t1 USING INDEX i1 (a=?)}}