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https://github.com/sqlite/sqlite.git
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Split FROM-clause subquery flattening and code generation into separate loops.
FossilOrigin-Name: be8e3fc70e4c13b28b07985df3457960f58ffddd
This commit is contained in:
drh
188
src/select.c
188
src/select.c
@@ -4842,14 +4842,54 @@ int sqlite3Select(
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}
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#endif
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/* Generate code for all sub-queries in the FROM clause
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/* Try to flatten subqueries in the FROM clause into the main query
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*/
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#if !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW)
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for(i=0; !p->pPrior && i<pTabList->nSrc; i++){
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struct SrcList_item *pItem = &pTabList->a[i];
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SelectDest dest;
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Select *pSub = pItem->pSelect;
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int isAggSub;
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if( pSub==0 ) continue;
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isAggSub = (pSub->selFlags & SF_Aggregate)!=0;
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if( flattenSubquery(pParse, p, i, isAgg, isAggSub) ){
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/* This subquery can be absorbed into its parent. */
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if( isAggSub ){
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isAgg = 1;
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p->selFlags |= SF_Aggregate;
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}
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i = -1;
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}
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pTabList = p->pSrc;
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if( db->mallocFailed ) goto select_end;
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if( !IgnorableOrderby(pDest) ){
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sSort.pOrderBy = p->pOrderBy;
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}
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}
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#endif
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#ifndef SQLITE_OMIT_COMPOUND_SELECT
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/* Handle compound SELECT statements using the separate multiSelect()
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** procedure.
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*/
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if( p->pPrior ){
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rc = multiSelect(pParse, p, pDest);
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explainSetInteger(pParse->iSelectId, iRestoreSelectId);
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#if SELECTTRACE_ENABLED
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SELECTTRACE(1,pParse,p,("end compound-select processing\n"));
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pParse->nSelectIndent--;
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#endif
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return rc;
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}
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#endif
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/* Generate code for all sub-queries in the FROM clause
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*/
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#if !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW)
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for(i=0; i<pTabList->nSrc; i++){
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struct SrcList_item *pItem = &pTabList->a[i];
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SelectDest dest;
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Select *pSub = pItem->pSelect;
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if( pSub==0 ) continue;
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@@ -4875,87 +4915,73 @@ int sqlite3Select(
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*/
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pParse->nHeight += sqlite3SelectExprHeight(p);
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isAggSub = (pSub->selFlags & SF_Aggregate)!=0;
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if( flattenSubquery(pParse, p, i, isAgg, isAggSub) ){
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/* This subquery can be absorbed into its parent. */
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if( isAggSub ){
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isAgg = 1;
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p->selFlags |= SF_Aggregate;
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}
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i = -1;
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}else{
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if( (pItem->jointype & JT_OUTER)==0
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&& pushDownWhereTerms(db, pSub, p->pWhere, pItem->iCursor)
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){
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if( (pItem->jointype & JT_OUTER)==0
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&& pushDownWhereTerms(db, pSub, p->pWhere, pItem->iCursor)
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){
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#if SELECTTRACE_ENABLED
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if( sqlite3SelectTrace & 0x100 ){
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SELECTTRACE(0x100,pParse,p,("After WHERE-clause push-down:\n"));
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sqlite3TreeViewSelect(0, p, 0);
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}
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if( sqlite3SelectTrace & 0x100 ){
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SELECTTRACE(0x100,pParse,p,("After WHERE-clause push-down:\n"));
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sqlite3TreeViewSelect(0, p, 0);
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}
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#endif
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}
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if( pTabList->nSrc==1
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&& (p->selFlags & SF_All)==0
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&& OptimizationEnabled(db, SQLITE_SubqCoroutine)
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){
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/* Implement a co-routine that will return a single row of the result
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** set on each invocation.
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*/
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int addrTop = sqlite3VdbeCurrentAddr(v)+1;
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pItem->regReturn = ++pParse->nMem;
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sqlite3VdbeAddOp3(v, OP_InitCoroutine, pItem->regReturn, 0, addrTop);
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VdbeComment((v, "%s", pItem->pTab->zName));
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pItem->addrFillSub = addrTop;
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sqlite3SelectDestInit(&dest, SRT_Coroutine, pItem->regReturn);
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explainSetInteger(pItem->iSelectId, (u8)pParse->iNextSelectId);
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sqlite3Select(pParse, pSub, &dest);
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pItem->pTab->nRowLogEst = sqlite3LogEst(pSub->nSelectRow);
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pItem->viaCoroutine = 1;
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pItem->regResult = dest.iSdst;
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sqlite3VdbeAddOp1(v, OP_EndCoroutine, pItem->regReturn);
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sqlite3VdbeJumpHere(v, addrTop-1);
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sqlite3ClearTempRegCache(pParse);
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}
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if( pTabList->nSrc==1
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&& (p->selFlags & SF_All)==0
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&& OptimizationEnabled(db, SQLITE_SubqCoroutine)
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){
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/* Implement a co-routine that will return a single row of the result
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** set on each invocation.
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*/
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int addrTop = sqlite3VdbeCurrentAddr(v)+1;
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pItem->regReturn = ++pParse->nMem;
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sqlite3VdbeAddOp3(v, OP_InitCoroutine, pItem->regReturn, 0, addrTop);
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VdbeComment((v, "%s", pItem->pTab->zName));
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pItem->addrFillSub = addrTop;
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sqlite3SelectDestInit(&dest, SRT_Coroutine, pItem->regReturn);
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explainSetInteger(pItem->iSelectId, (u8)pParse->iNextSelectId);
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sqlite3Select(pParse, pSub, &dest);
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pItem->pTab->nRowLogEst = sqlite3LogEst(pSub->nSelectRow);
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pItem->viaCoroutine = 1;
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pItem->regResult = dest.iSdst;
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sqlite3VdbeAddOp1(v, OP_EndCoroutine, pItem->regReturn);
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sqlite3VdbeJumpHere(v, addrTop-1);
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sqlite3ClearTempRegCache(pParse);
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}else{
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/* Generate a subroutine that will fill an ephemeral table with
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** the content of this subquery. pItem->addrFillSub will point
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** to the address of the generated subroutine. pItem->regReturn
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** is a register allocated to hold the subroutine return address
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*/
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int topAddr;
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int onceAddr = 0;
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int retAddr;
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assert( pItem->addrFillSub==0 );
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pItem->regReturn = ++pParse->nMem;
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topAddr = sqlite3VdbeAddOp2(v, OP_Integer, 0, pItem->regReturn);
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pItem->addrFillSub = topAddr+1;
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if( pItem->isCorrelated==0 ){
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/* If the subquery is not correlated and if we are not inside of
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** a trigger, then we only need to compute the value of the subquery
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** once. */
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onceAddr = sqlite3CodeOnce(pParse); VdbeCoverage(v);
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VdbeComment((v, "materialize \"%s\"", pItem->pTab->zName));
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}else{
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/* Generate a subroutine that will fill an ephemeral table with
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** the content of this subquery. pItem->addrFillSub will point
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** to the address of the generated subroutine. pItem->regReturn
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** is a register allocated to hold the subroutine return address
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*/
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int topAddr;
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int onceAddr = 0;
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int retAddr;
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assert( pItem->addrFillSub==0 );
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pItem->regReturn = ++pParse->nMem;
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topAddr = sqlite3VdbeAddOp2(v, OP_Integer, 0, pItem->regReturn);
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pItem->addrFillSub = topAddr+1;
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if( pItem->isCorrelated==0 ){
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/* If the subquery is not correlated and if we are not inside of
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** a trigger, then we only need to compute the value of the subquery
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** once. */
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onceAddr = sqlite3CodeOnce(pParse); VdbeCoverage(v);
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VdbeComment((v, "materialize \"%s\"", pItem->pTab->zName));
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}else{
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VdbeNoopComment((v, "materialize \"%s\"", pItem->pTab->zName));
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}
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sqlite3SelectDestInit(&dest, SRT_EphemTab, pItem->iCursor);
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explainSetInteger(pItem->iSelectId, (u8)pParse->iNextSelectId);
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sqlite3Select(pParse, pSub, &dest);
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pItem->pTab->nRowLogEst = sqlite3LogEst(pSub->nSelectRow);
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if( onceAddr ) sqlite3VdbeJumpHere(v, onceAddr);
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retAddr = sqlite3VdbeAddOp1(v, OP_Return, pItem->regReturn);
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VdbeComment((v, "end %s", pItem->pTab->zName));
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sqlite3VdbeChangeP1(v, topAddr, retAddr);
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sqlite3ClearTempRegCache(pParse);
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VdbeNoopComment((v, "materialize \"%s\"", pItem->pTab->zName));
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}
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sqlite3SelectDestInit(&dest, SRT_EphemTab, pItem->iCursor);
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explainSetInteger(pItem->iSelectId, (u8)pParse->iNextSelectId);
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sqlite3Select(pParse, pSub, &dest);
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pItem->pTab->nRowLogEst = sqlite3LogEst(pSub->nSelectRow);
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if( onceAddr ) sqlite3VdbeJumpHere(v, onceAddr);
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retAddr = sqlite3VdbeAddOp1(v, OP_Return, pItem->regReturn);
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VdbeComment((v, "end %s", pItem->pTab->zName));
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sqlite3VdbeChangeP1(v, topAddr, retAddr);
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sqlite3ClearTempRegCache(pParse);
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}
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if( db->mallocFailed ){
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goto select_end;
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}
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pParse->nHeight -= sqlite3SelectExprHeight(p);
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pTabList = p->pSrc;
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if( !IgnorableOrderby(pDest) ){
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sSort.pOrderBy = p->pOrderBy;
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}
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}
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pEList = p->pEList;
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#endif
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@@ -4971,20 +4997,6 @@ int sqlite3Select(
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}
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#endif
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#ifndef SQLITE_OMIT_COMPOUND_SELECT
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/* If there is are a sequence of queries, do the earlier ones first.
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*/
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if( p->pPrior ){
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rc = multiSelect(pParse, p, pDest);
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explainSetInteger(pParse->iSelectId, iRestoreSelectId);
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#if SELECTTRACE_ENABLED
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SELECTTRACE(1,pParse,p,("end compound-select processing\n"));
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pParse->nSelectIndent--;
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#endif
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return rc;
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}
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#endif
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/* If the query is DISTINCT with an ORDER BY but is not an aggregate, and
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** if the select-list is the same as the ORDER BY list, then this query
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** can be rewritten as a GROUP BY. In other words, this:
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