Use symbolic names ONEPASS_OFF, ONEPASS_SINGLE, and ONEPASS_MULTI for the

various modes of the one-pass optimization.

FossilOrigin-Name: 16e56bdadef903c6439a487f2683388aeeb0c625

6 files changed, 43 insertions, 35 deletions

diff --git a/src/delete.c b/src/delete.c
index caf73ab2b..7c2f3fcd0 100644
--- a/src/delete.c
+++ b/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 eOnePass;          /* Non-zero for one-pass algorithm without the FIFO */
+  int eOnePass;          /* ONEPASS_OFF or _SINGLE or _MULTI */
   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 */
@@ -400,14 +400,14 @@ void sqlite3DeleteFrom(
     ** 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.
+    **  ONEPASS_OFF:    Two-pass approach - use a FIFO for rowids/PK values.
+    **  ONEPASS_SINGLE: One-pass approach - at most one row deleted.
+    **  ONEPASS_MULTI:  One-pass approach - any number of rows may be deleted.
     */
     pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, 0, 0, wcf, iTabCur+1);
     if( pWInfo==0 ) goto delete_from_cleanup;
     eOnePass = sqlite3WhereOkOnePass(pWInfo, aiCurOnePass);
-    assert( IsVirtual(pTab)==0 || eOnePass==0 );
+    assert( IsVirtual(pTab)==0 || eOnePass==ONEPASS_OFF );
   
     /* Keep track of the number of rows to be deleted */
     if( db->flags & SQLITE_CountRows ){
@@ -428,7 +428,7 @@ void sqlite3DeleteFrom(
       if( iKey>pParse->nMem ) pParse->nMem = iKey;
     }
   
-    if( eOnePass ){
+    if( eOnePass!=ONEPASS_OFF ){
       /* 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.  */
@@ -460,7 +460,7 @@ void sqlite3DeleteFrom(
   
     /* If this DELETE cannot use the ONEPASS strategy, this is the 
     ** end of the WHERE loop */
-    if( eOnePass ){
+    if( eOnePass!=ONEPASS_OFF ){
       addrBypass = sqlite3VdbeMakeLabel(v);
     }else{
       sqlite3WhereEnd(pWInfo);
@@ -473,7 +473,7 @@ void sqlite3DeleteFrom(
     */
     if( !isView ){
       int iAddrOnce = 0;
-      if( eOnePass==2 ){
+      if( eOnePass==ONEPASS_MULTI ){
         iAddrOnce = sqlite3CodeOnce(pParse); VdbeCoverage(v);
       }
       testcase( IsVirtual(pTab) );
@@ -481,13 +481,13 @@ void sqlite3DeleteFrom(
                                  &iDataCur, &iIdxCur);
       assert( pPk || IsVirtual(pTab) || iDataCur==iTabCur );
       assert( pPk || IsVirtual(pTab) || iIdxCur==iDataCur+1 );
-      if( eOnePass==2 ) sqlite3VdbeJumpHere(v, iAddrOnce);
+      if( eOnePass==ONEPASS_MULTI ) sqlite3VdbeJumpHere(v, iAddrOnce);
     }
   
     /* Set up a loop over the rowids/primary-keys that were found in the
     ** where-clause loop above.
     */
-    if( eOnePass ){
+    if( eOnePass!=ONEPASS_OFF ){
       assert( nKey==nPk );  /* OP_Found will use an unpacked key */
       if( aToOpen[iDataCur-iTabCur] ){
         assert( pPk!=0 || pTab->pSelect!=0 );
@@ -525,7 +525,7 @@ void sqlite3DeleteFrom(
     }
   
     /* End of the loop over all rowids/primary-keys. */
-    if( eOnePass ){
+    if( eOnePass!=ONEPASS_OFF ){
       sqlite3VdbeResolveLabel(v, addrBypass);
       sqlite3WhereEnd(pWInfo);
     }else if( pPk ){
@@ -601,13 +601,13 @@ delete_from_cleanup:
 **       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.
+**   Parameter eMode may be passed either ONEPASS_OFF (0), ONEPASS_SINGLE, or
+**   ONEPASS_MULTI.  If eMode is not ONEPASS_OFF, then the cursor
+**   iDataCur already points to the row to delete. If eMode is ONEPASS_OFF
+**   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
+**   If eMode is ONEPASS_MULTI, 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
@@ -629,7 +629,7 @@ 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 eMode,          /* See explanation above */
+  u8 eMode,          /* ONEPASS_OFF, _SINGLE, or _MULTI.  See above */
   int iIdxNoSeek     /* Cursor number of cursor that does not need seeking */
 ){
   Vdbe *v = pParse->pVdbe;        /* Vdbe */
@@ -647,7 +647,7 @@ void sqlite3GenerateRowDelete(
   ** not attempt to delete it or fire any DELETE triggers.  */
   iLabel = sqlite3VdbeMakeLabel(v);
   opSeek = HasRowid(pTab) ? OP_NotExists : OP_NotFound;
-  if( eMode==0 ){
+  if( eMode==ONEPASS_OFF ){
     sqlite3VdbeAddOp4Int(v, opSeek, iDataCur, iLabel, iPk, nPk);
     VdbeCoverageIf(v, opSeek==OP_NotExists);
     VdbeCoverageIf(v, opSeek==OP_NotFound);
@@ -715,7 +715,7 @@ void sqlite3GenerateRowDelete(
     if( iIdxNoSeek>=0 ){
       sqlite3VdbeAddOp1(v, OP_Delete, iIdxNoSeek);
     }
-    sqlite3VdbeChangeP5(v, eMode==2);
+    sqlite3VdbeChangeP5(v, eMode==ONEPASS_MULTI);
   }
 
   /* Do any ON CASCADE, SET NULL or SET DEFAULT operations required to
diff --git a/src/insert.c b/src/insert.c
index 21e1a2577..613277835 100644
--- a/src/insert.c
+++ b/src/insert.c
@@ -1347,7 +1347,8 @@ void sqlite3GenerateConstraintChecks(
         if( pTrigger || sqlite3FkRequired(pParse, pTab, 0, 0) ){
           sqlite3MultiWrite(pParse);
           sqlite3GenerateRowDelete(pParse, pTab, pTrigger, iDataCur, iIdxCur,
-                                   regNewData, 1, 0, OE_Replace, 1, -1);
+                                   regNewData, 1, 0, OE_Replace,
+                                   ONEPASS_SINGLE, -1);
         }else if( pTab->pIndex ){
           sqlite3MultiWrite(pParse);
           sqlite3GenerateRowIndexDelete(pParse, pTab, iDataCur, iIdxCur, 0, -1);
@@ -1528,7 +1529,8 @@ void sqlite3GenerateConstraintChecks(
           pTrigger = sqlite3TriggersExist(pParse, pTab, TK_DELETE, 0, 0);
         }
         sqlite3GenerateRowDelete(pParse, pTab, pTrigger, iDataCur, iIdxCur,
-            regR, nPkField, 0, OE_Replace, pIdx==pPk, -1);
+            regR, nPkField, 0, OE_Replace,
+            (pIdx==pPk ? ONEPASS_SINGLE : ONEPASS_OFF), -1);
         seenReplace = 1;
         break;
       }
diff --git a/src/sqliteInt.h b/src/sqliteInt.h
index 7fc3464d1..747f19b39 100644
--- a/src/sqliteInt.h
+++ b/src/sqliteInt.h
@@ -3381,6 +3381,9 @@ int sqlite3WhereIsSorted(WhereInfo*);
 int sqlite3WhereContinueLabel(WhereInfo*);
 int sqlite3WhereBreakLabel(WhereInfo*);
 int sqlite3WhereOkOnePass(WhereInfo*, int*);
+#define ONEPASS_OFF      0        /* Use of ONEPASS not allowed */
+#define ONEPASS_SINGLE   1        /* ONEPASS valid for a single row update */
+#define ONEPASS_MULTI    2        /* ONEPASS is valid for multiple rows */
 void sqlite3ExprCodeLoadIndexColumn(Parse*, Index*, int, int, int);
 int sqlite3ExprCodeGetColumn(Parse*, Table*, int, int, int, u8);
 void sqlite3ExprCodeGetColumnOfTable(Vdbe*, Table*, int, int, int);
diff --git a/src/where.c b/src/where.c
index 526e06afe..69b7c064e 100644
--- a/src/where.c
+++ b/src/where.c
@@ -69,9 +69,11 @@ int sqlite3WhereBreakLabel(WhereInfo *pWInfo){
 }
 
 /*
-** Return TRUE if an UPDATE or DELETE statement can operate directly on
-** the rowids returned by a WHERE clause.  Return FALSE if doing an
-** UPDATE or DELETE might change subsequent WHERE clause results.
+** Return ONEPASS_OFF (0) if an UPDATE or DELETE statement is unable to
+** operate directly on the rowis returned by a WHERE clause.  Return
+** ONEPASS_SINGLE (1) if the statement can operation directly because only
+** a single row is to be changed.  Return ONEPASS_MULTI (2) if the one-pass
+** optimization can be used on multiple 
 **
 ** If the ONEPASS optimization is used (if this routine returns true)
 ** then also write the indices of open cursors used by ONEPASS
@@ -85,7 +87,7 @@ int sqlite3WhereBreakLabel(WhereInfo *pWInfo){
 */
 int sqlite3WhereOkOnePass(WhereInfo *pWInfo, int *aiCur){
   memcpy(aiCur, pWInfo->aiCurOnePass, sizeof(int)*2);
-  return pWInfo->okOnePass;
+  return pWInfo->eOnePass;
 }
 
 /*
@@ -4017,6 +4019,7 @@ WhereInfo *sqlite3WhereBegin(
   pWInfo->iBreak = pWInfo->iContinue = sqlite3VdbeMakeLabel(v);
   pWInfo->wctrlFlags = wctrlFlags;
   pWInfo->savedNQueryLoop = pParse->nQueryLoop;
+  assert( pWInfo->eOnePass==ONEPASS_OFF );  /* ONEPASS defaults to OFF */
   pMaskSet = &pWInfo->sMaskSet;
   sWLB.pWInfo = pWInfo;
   sWLB.pWC = &pWInfo->sWC;
@@ -4209,7 +4212,7 @@ WhereInfo *sqlite3WhereBegin(
     if( bOnerow || ( (wctrlFlags & WHERE_ONEPASS_MULTIROW)
        && 0==(wsFlags & WHERE_VIRTUALTABLE)
     )){
-      pWInfo->okOnePass = bOnerow ? 1 : 2;
+      pWInfo->eOnePass = bOnerow ? ONEPASS_SINGLE : ONEPASS_MULTI;
       if( HasRowid(pTabList->a[0].pTab) ){
         pWInfo->a[0].pWLoop->wsFlags &= ~WHERE_IDX_ONLY;
       }
@@ -4243,15 +4246,15 @@ WhereInfo *sqlite3WhereBegin(
     if( (pLoop->wsFlags & WHERE_IDX_ONLY)==0
          && (wctrlFlags & WHERE_OMIT_OPEN_CLOSE)==0 ){
       int op = OP_OpenRead;
-      if( pWInfo->okOnePass ){
+      if( pWInfo->eOnePass!=ONEPASS_OFF ){
         op = OP_OpenWrite;
         pWInfo->aiCurOnePass[0] = pTabItem->iCursor;
       };
       sqlite3OpenTable(pParse, pTabItem->iCursor, iDb, pTab, op);
       assert( pTabItem->iCursor==pLevel->iTabCur );
-      testcase( !pWInfo->okOnePass && pTab->nCol==BMS-1 );
-      testcase( !pWInfo->okOnePass && pTab->nCol==BMS );
-      if( !pWInfo->okOnePass && pTab->nCol<BMS && HasRowid(pTab) ){
+      testcase( pWInfo->eOnePass==ONEPASS_OFF && pTab->nCol==BMS-1 );
+      testcase( pWInfo->eOnePass==ONEPASS_OFF && pTab->nCol==BMS );
+      if( pWInfo->eOnePass==ONEPASS_OFF && pTab->nCol<BMS && HasRowid(pTab) ){
         Bitmask b = pTabItem->colUsed;
         int n = 0;
         for(; b; b=b>>1, n++){}
@@ -4279,7 +4282,7 @@ WhereInfo *sqlite3WhereBegin(
         ** WITHOUT ROWID table.  No need for a separate index */
         iIndexCur = pLevel->iTabCur;
         op = 0;
-      }else if( pWInfo->okOnePass ){
+      }else if( pWInfo->eOnePass!=ONEPASS_OFF ){
         Index *pJ = pTabItem->pTab->pIndex;
         iIndexCur = iIdxCur;
         assert( wctrlFlags & WHERE_ONEPASS_DESIRED );
@@ -4487,7 +4490,7 @@ void sqlite3WhereEnd(WhereInfo *pWInfo){
      && (pWInfo->wctrlFlags & WHERE_OMIT_OPEN_CLOSE)==0
     ){
       int ws = pLoop->wsFlags;
-      if( !pWInfo->okOnePass && (ws & WHERE_IDX_ONLY)==0 ){
+      if( pWInfo->eOnePass==ONEPASS_OFF && (ws & WHERE_IDX_ONLY)==0 ){
         sqlite3VdbeAddOp1(v, OP_Close, pTabItem->iCursor);
       }
       if( (ws & WHERE_INDEXED)!=0
diff --git a/src/whereInt.h b/src/whereInt.h
index 65c118004..cae09acc8 100644
--- a/src/whereInt.h
+++ b/src/whereInt.h
@@ -412,7 +412,7 @@ struct WhereInfo {
   u16 wctrlFlags;           /* Flags originally passed to sqlite3WhereBegin() */
   i8 nOBSat;                /* Number of ORDER BY terms satisfied by indices */
   u8 sorted;                /* True if really sorted (not just grouped) */
-  u8 okOnePass;             /* Ok to use one-pass algorithm for UPDATE/DELETE */
+  u8 eOnePass;              /* ONEPASS_OFF, or _SINGLE, or _MULTI */
   u8 untestedTerms;         /* Not all WHERE terms resolved by outer loop */
   u8 eDistinct;             /* One of the WHERE_DISTINCT_* values below */
   u8 nLevel;                /* Number of nested loop */
diff --git a/src/wherecode.c b/src/wherecode.c
index 1f65a93e6..4fb608401 100644
--- a/src/wherecode.c
+++ b/src/wherecode.c
@@ -1069,7 +1069,7 @@ Bitmask sqlite3WhereCodeOneLoopStart(
       iRowidReg = ++pParse->nMem;
       sqlite3VdbeAddOp2(v, OP_IdxRowid, iIdxCur, iRowidReg);
       sqlite3ExprCacheStore(pParse, iCur, -1, iRowidReg);
-      if( pWInfo->okOnePass ){
+      if( pWInfo->eOnePass!=ONEPASS_OFF ){
         sqlite3VdbeAddOp3(v, OP_NotExists, iCur, 0, iRowidReg);
         VdbeCoverage(v);
       }else{