From: drh <> Date: Fri, 3 Dec 2021 18:53:53 +0000 (+0000) Subject: Factor the noop-join-elimination optimization out of the sqlite3WhereBegin() X-Git-Tag: version-3.38.0~197 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=70b403b667a3ec829e5435271c905cb7ba544e17;p=thirdparty%2Fsqlite.git Factor the noop-join-elimination optimization out of the sqlite3WhereBegin() routine and into a separate "no-inline" subroutine, in order to reduce the complexity of sqlite3WhereBegin() and thereby encourage C compilers to inline sqlite3WhereCodeOneLoopStart(). FossilOrigin-Name: 6225e9abcb0261fefca4a26530524ffc449f937f8ae1ece718af2c3c3d73d78d --- diff --git a/manifest b/manifest index e2d4a70289..1fc8dc6703 100644 --- a/manifest +++ b/manifest @@ -1,5 +1,5 @@ -C Fix\sexprAnalyze()\safter\srecent\sperformance\senhancements\sso\sthat\sit\sis\sable\nto\shandle\sIF_NULL_ROW\sopcode\scorrectly,\sagain. -D 2021-12-03T15:48:42.503 +C Factor\sthe\snoop-join-elimination\soptimization\sout\sof\sthe\ssqlite3WhereBegin()\nroutine\sand\sinto\sa\sseparate\s"no-inline"\ssubroutine,\sin\sorder\sto\sreduce\sthe\ncomplexity\sof\ssqlite3WhereBegin()\sand\sthereby\sencourage\sC\scompilers\sto\ninline\ssqlite3WhereCodeOneLoopStart(). +D 2021-12-03T18:53:53.434 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724 @@ -637,7 +637,7 @@ F src/vxworks.h d2988f4e5a61a4dfe82c6524dd3d6e4f2ce3cdb9 F src/wal.c ed0398a7adf02c31e34aada42cc86c58f413a7afe5f741a5d373ad087abde028 F src/wal.h c3aa7825bfa2fe0d85bef2db94655f99870a285778baa36307c0a16da32b226a F src/walker.c f890a3298418d7cba3b69b8803594fdc484ea241206a8dfa99db6dd36f8cbb3b -F src/where.c b50391df607937593596fbb8ea39f673d9a3715a65750567b442d22dd20720ca +F src/where.c 5bd26902ddf3e385c0df9429b10e7358bbd0430c470ec1d2a53065723c4a55d2 F src/whereInt.h 1630d9418512b080598e9a72b8af6b8bd1b9ab13fee1458f151762b6df206791 F src/wherecode.c 1f5b62f46d284c8886945eb7438415bc27e23e87bb60b9ee468fa6bd31268f33 F src/whereexpr.c 19394cb463003e9cc9305730b1508b8817a22bb7247170d81234b691a7f05b89 @@ -1933,7 +1933,7 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0 -P f3d6853ee80be2dc6d7236d98b850beb0e1931a624d4f5b194c8db742cde7ec5 -R f7c21b32b86d486ed00c79fd5643ce8f +P 8029e6bab508bf0b8ec1df00a829c5d4de2a84d66dc56b9ff03da879ceef7788 +R 963c220f26757d3ffbc2edfb4f7e86f0 U drh -Z 7b145c2e945c01598a45c251b2a2a878 +Z 180dbfc838231c2ae95c395bdf32b1d2 diff --git a/manifest.uuid b/manifest.uuid index 2be18ad032..9b8ce11932 100644 --- a/manifest.uuid +++ b/manifest.uuid @@ -1 +1 @@ -8029e6bab508bf0b8ec1df00a829c5d4de2a84d66dc56b9ff03da879ceef7788 \ No newline at end of file +6225e9abcb0261fefca4a26530524ffc449f937f8ae1ece718af2c3c3d73d78d \ No newline at end of file diff --git a/src/where.c b/src/where.c index 925f98af16..f1abd5483c 100644 --- a/src/where.c +++ b/src/where.c @@ -4743,6 +4743,96 @@ static void showAllWhereLoops(WhereInfo *pWInfo, WhereClause *pWC){ # define WHERETRACE_ALL_LOOPS(W,C) #endif +/* Attempt to omit tables from a join that do not affect the result. +** For a table to not affect the result, the following must be true: +** +** 1) The query must not be an aggregate. +** 2) The table must be the RHS of a LEFT JOIN. +** 3) Either the query must be DISTINCT, or else the ON or USING clause +** must contain a constraint that limits the scan of the table to +** at most a single row. +** 4) The table must not be referenced by any part of the query apart +** from its own USING or ON clause. +** +** For example, given: +** +** CREATE TABLE t1(ipk INTEGER PRIMARY KEY, v1); +** CREATE TABLE t2(ipk INTEGER PRIMARY KEY, v2); +** CREATE TABLE t3(ipk INTEGER PRIMARY KEY, v3); +** +** then table t2 can be omitted from the following: +** +** SELECT v1, v3 FROM t1 +** LEFT JOIN t2 ON (t1.ipk=t2.ipk) +** LEFT JOIN t3 ON (t1.ipk=t3.ipk) +** +** or from: +** +** SELECT DISTINCT v1, v3 FROM t1 +** LEFT JOIN t2 +** LEFT JOIN t3 ON (t1.ipk=t3.ipk) +*/ +static SQLITE_NOINLINE Bitmask whereOmitNoopJoin( + WhereInfo *pWInfo, + Bitmask notReady +){ + int i; + Bitmask tabUsed; + + /* Preconditions checked by the caller */ + assert( pWInfo->nLevel>=2 ); + assert( OptimizationEnabled(pWInfo->pParse->db, SQLITE_OmitNoopJoin) ); + + /* These two preconditions checked by the caller combine to guarantee + ** condition (1) of the header comment */ + assert( pWInfo->pResultSet!=0 ); + assert( 0==(pWInfo->wctrlFlags & WHERE_AGG_DISTINCT) ); + + tabUsed = sqlite3WhereExprListUsage(&pWInfo->sMaskSet, pWInfo->pResultSet); + if( pWInfo->pOrderBy ){ + tabUsed |= sqlite3WhereExprListUsage(&pWInfo->sMaskSet, pWInfo->pOrderBy); + } + for(i=pWInfo->nLevel-1; i>=1; i--){ + WhereTerm *pTerm, *pEnd; + SrcItem *pItem; + WhereLoop *pLoop; + pLoop = pWInfo->a[i].pWLoop; + pItem = &pWInfo->pTabList->a[pLoop->iTab]; + if( (pItem->fg.jointype & JT_LEFT)==0 ) continue; + if( (pWInfo->wctrlFlags & WHERE_WANT_DISTINCT)==0 + && (pLoop->wsFlags & WHERE_ONEROW)==0 + ){ + continue; + } + if( (tabUsed & pLoop->maskSelf)!=0 ) continue; + pEnd = pWInfo->sWC.a + pWInfo->sWC.nTerm; + for(pTerm=pWInfo->sWC.a; pTermprereqAll & pLoop->maskSelf)!=0 ){ + if( !ExprHasProperty(pTerm->pExpr, EP_FromJoin) + || pTerm->pExpr->iRightJoinTable!=pItem->iCursor + ){ + break; + } + } + } + if( pTerm drop loop %c not used\n", pLoop->cId)); + notReady &= ~pLoop->maskSelf; + for(pTerm=pWInfo->sWC.a; pTermprereqAll & pLoop->maskSelf)!=0 ){ + pTerm->wtFlags |= TERM_CODED; + } + } + if( i!=pWInfo->nLevel-1 ){ + int nByte = (pWInfo->nLevel-1-i) * sizeof(WhereLevel); + memmove(&pWInfo->a[i], &pWInfo->a[i+1], nByte); + } + pWInfo->nLevel--; + assert( pWInfo->nLevel>0 ); + } + return notReady; +} + /* ** Generate the beginning of the loop used for WHERE clause processing. ** The return value is a pointer to an opaque structure that contains @@ -5111,34 +5201,15 @@ WhereInfo *sqlite3WhereBegin( } #endif - /* Attempt to omit tables from the join that do not affect the result. - ** For a table to not affect the result, the following must be true: - ** - ** 1) The query must not be an aggregate. - ** 2) The table must be the RHS of a LEFT JOIN. - ** 3) Either the query must be DISTINCT, or else the ON or USING clause - ** must contain a constraint that limits the scan of the table to - ** at most a single row. - ** 4) The table must not be referenced by any part of the query apart - ** from its own USING or ON clause. - ** - ** For example, given: + /* Attempt to omit tables from a join that do not affect the result. + ** See the comment on whereOmitNoopJoin() for further information. ** - ** CREATE TABLE t1(ipk INTEGER PRIMARY KEY, v1); - ** CREATE TABLE t2(ipk INTEGER PRIMARY KEY, v2); - ** CREATE TABLE t3(ipk INTEGER PRIMARY KEY, v3); - ** - ** then table t2 can be omitted from the following: - ** - ** SELECT v1, v3 FROM t1 - ** LEFT JOIN t2 ON (t1.ipk=t2.ipk) - ** LEFT JOIN t3 ON (t1.ipk=t3.ipk) - ** - ** or from: - ** - ** SELECT DISTINCT v1, v3 FROM t1 - ** LEFT JOIN t2 - ** LEFT JOIN t3 ON (t1.ipk=t3.ipk) + ** This query optimization is factored out into a separate "no-inline" + ** procedure to keep the sqlite3WhereBegin() procedure from becoming + ** too large. If sqlite3WhereBegin() becomes too large, that prevents + ** some C-compiler optimizers from in-lining the + ** sqlite3WhereCodeOneLoopStart() procedure, and it is important to + ** in-line sqlite3WhereCodeOneLoopStart() for performance reasons. */ notReady = ~(Bitmask)0; if( pWInfo->nLevel>=2 @@ -5146,49 +5217,11 @@ WhereInfo *sqlite3WhereBegin( && 0==(wctrlFlags & WHERE_AGG_DISTINCT) /* condition (1) above */ && OptimizationEnabled(db, SQLITE_OmitNoopJoin) ){ - int i; - Bitmask tabUsed = sqlite3WhereExprListUsage(pMaskSet, pResultSet); - if( sWLB.pOrderBy ){ - tabUsed |= sqlite3WhereExprListUsage(pMaskSet, sWLB.pOrderBy); - } - for(i=pWInfo->nLevel-1; i>=1; i--){ - WhereTerm *pTerm, *pEnd; - SrcItem *pItem; - pLoop = pWInfo->a[i].pWLoop; - pItem = &pWInfo->pTabList->a[pLoop->iTab]; - if( (pItem->fg.jointype & JT_LEFT)==0 ) continue; - if( (wctrlFlags & WHERE_WANT_DISTINCT)==0 - && (pLoop->wsFlags & WHERE_ONEROW)==0 - ){ - continue; - } - if( (tabUsed & pLoop->maskSelf)!=0 ) continue; - pEnd = sWLB.pWC->a + sWLB.pWC->nTerm; - for(pTerm=sWLB.pWC->a; pTermprereqAll & pLoop->maskSelf)!=0 ){ - if( !ExprHasProperty(pTerm->pExpr, EP_FromJoin) - || pTerm->pExpr->iRightJoinTable!=pItem->iCursor - ){ - break; - } - } - } - if( pTerm drop loop %c not used\n", pLoop->cId)); - notReady &= ~pLoop->maskSelf; - for(pTerm=sWLB.pWC->a; pTermprereqAll & pLoop->maskSelf)!=0 ){ - pTerm->wtFlags |= TERM_CODED; - } - } - if( i!=pWInfo->nLevel-1 ){ - int nByte = (pWInfo->nLevel-1-i) * sizeof(WhereLevel); - memmove(&pWInfo->a[i], &pWInfo->a[i+1], nByte); - } - pWInfo->nLevel--; - nTabList--; - } + notReady = whereOmitNoopJoin(pWInfo, notReady); + nTabList = pWInfo->nLevel; + assert( nTabList>0 ); } + #if defined(WHERETRACE_ENABLED) if( sqlite3WhereTrace & 0x100 ){ /* Display all terms of the WHERE clause */ sqlite3DebugPrintf("---- WHERE clause at end of analysis:\n");