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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.

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FossilOrigin-Name: eaeb2b80f6f8f83679c8323a81bb39570ec946fe
This commit is contained in:
dan
2015-09-12 19:26:11 +00:00
parent 04abf0878f
commit f0ee1d3c12
13 changed files with 338 additions and 113 deletions
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120
src/delete.c
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@@ -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)
&& 0==sqlite3FkRequired(pParse, pTab, 0, 0)
){
if( rcauth==SQLITE_OK && pWhere==0 && !bComplex && !IsVirtual(pTab) ){
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,
WHERE_ONEPASS_DESIRED|WHERE_DUPLICATES_OK,
iTabCur+1);
pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, 0, 0, wcf, 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 ){
/* For ONEPASS, no need to store the rowid/primary-key. There is only
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 if( pPk ){
/* Construct a composite key for the row to be deleted and remember it */
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 */
nKey = 1; /* OP_Seek always uses a single rowid */
sqlite3VdbeAddOp2(v, OP_RowSetAdd, iRowSet, iKey);
if( pPk ){
/* 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{
/* 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 */
sqlite3WhereEnd(pWInfo);
if( okOnePass ){
/* Bypass the delete logic below if the WHERE loop found zero rows */
/* If this DELETE cannot use the ONEPASS strategy, this is the
** end of the WHERE loop */
if( eOnePass ){
addrBypass = sqlite3VdbeMakeLabel(v);
sqlite3VdbeGoto(v, addrBypass);
sqlite3VdbeJumpHere(v, addrDelete);
}else{
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 ){
/* Just one row. Hence the top-of-loop is a no-op */
if( eOnePass ){
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 */
@@ -737,11 +774,12 @@ 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);
&iPartIdxLabel, pPrior, r1);
sqlite3VdbeAddOp3(v, OP_IdxDelete, iIdxCur+i, r1,
pIdx->uniqNotNull ? pIdx->nKeyCol : pIdx->nColumn);
pIdx->uniqNotNull ? pIdx->nKeyCol : pIdx->nColumn);
sqlite3ResolvePartIdxLabel(pParse, iPartIdxLabel);
pPrior = pIdx;
}