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
This commit is contained in:
drh
parent
60a8e1b43c
commit
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manifest
12
manifest
@ -1,5 +1,5 @@
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C Fix\sexprAnalyze()\safter\srecent\sperformance\senhancements\sso\sthat\sit\sis\sable\nto\shandle\sIF_NULL_ROW\sopcode\scorrectly,\sagain.
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D 2021-12-03T15:48:42.503
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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().
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D 2021-12-03T18:53:53.434
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F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
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F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
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F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
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@ -637,7 +637,7 @@ F src/vxworks.h d2988f4e5a61a4dfe82c6524dd3d6e4f2ce3cdb9
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F src/wal.c ed0398a7adf02c31e34aada42cc86c58f413a7afe5f741a5d373ad087abde028
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F src/wal.h c3aa7825bfa2fe0d85bef2db94655f99870a285778baa36307c0a16da32b226a
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F src/walker.c f890a3298418d7cba3b69b8803594fdc484ea241206a8dfa99db6dd36f8cbb3b
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F src/where.c b50391df607937593596fbb8ea39f673d9a3715a65750567b442d22dd20720ca
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F src/where.c 5bd26902ddf3e385c0df9429b10e7358bbd0430c470ec1d2a53065723c4a55d2
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F src/whereInt.h 1630d9418512b080598e9a72b8af6b8bd1b9ab13fee1458f151762b6df206791
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F src/wherecode.c 1f5b62f46d284c8886945eb7438415bc27e23e87bb60b9ee468fa6bd31268f33
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F src/whereexpr.c 19394cb463003e9cc9305730b1508b8817a22bb7247170d81234b691a7f05b89
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@ -1933,7 +1933,7 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
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F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
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F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
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F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
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P f3d6853ee80be2dc6d7236d98b850beb0e1931a624d4f5b194c8db742cde7ec5
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R f7c21b32b86d486ed00c79fd5643ce8f
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P 8029e6bab508bf0b8ec1df00a829c5d4de2a84d66dc56b9ff03da879ceef7788
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R 963c220f26757d3ffbc2edfb4f7e86f0
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U drh
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Z 7b145c2e945c01598a45c251b2a2a878
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Z 180dbfc838231c2ae95c395bdf32b1d2
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@ -1 +1 @@
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8029e6bab508bf0b8ec1df00a829c5d4de2a84d66dc56b9ff03da879ceef7788
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6225e9abcb0261fefca4a26530524ffc449f937f8ae1ece718af2c3c3d73d78d
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171
src/where.c
171
src/where.c
@ -4743,6 +4743,96 @@ static void showAllWhereLoops(WhereInfo *pWInfo, WhereClause *pWC){
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# define WHERETRACE_ALL_LOOPS(W,C)
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#endif
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/* Attempt to omit tables from a join that do not affect the result.
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** For a table to not affect the result, the following must be true:
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**
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** 1) The query must not be an aggregate.
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** 2) The table must be the RHS of a LEFT JOIN.
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** 3) Either the query must be DISTINCT, or else the ON or USING clause
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** must contain a constraint that limits the scan of the table to
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** at most a single row.
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** 4) The table must not be referenced by any part of the query apart
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** from its own USING or ON clause.
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**
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** For example, given:
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**
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** CREATE TABLE t1(ipk INTEGER PRIMARY KEY, v1);
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** CREATE TABLE t2(ipk INTEGER PRIMARY KEY, v2);
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** CREATE TABLE t3(ipk INTEGER PRIMARY KEY, v3);
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**
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** then table t2 can be omitted from the following:
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**
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** SELECT v1, v3 FROM t1
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** LEFT JOIN t2 ON (t1.ipk=t2.ipk)
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** LEFT JOIN t3 ON (t1.ipk=t3.ipk)
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**
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** or from:
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**
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** SELECT DISTINCT v1, v3 FROM t1
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** LEFT JOIN t2
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** LEFT JOIN t3 ON (t1.ipk=t3.ipk)
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*/
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static SQLITE_NOINLINE Bitmask whereOmitNoopJoin(
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WhereInfo *pWInfo,
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Bitmask notReady
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){
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int i;
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Bitmask tabUsed;
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/* Preconditions checked by the caller */
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assert( pWInfo->nLevel>=2 );
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assert( OptimizationEnabled(pWInfo->pParse->db, SQLITE_OmitNoopJoin) );
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/* These two preconditions checked by the caller combine to guarantee
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** condition (1) of the header comment */
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assert( pWInfo->pResultSet!=0 );
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assert( 0==(pWInfo->wctrlFlags & WHERE_AGG_DISTINCT) );
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tabUsed = sqlite3WhereExprListUsage(&pWInfo->sMaskSet, pWInfo->pResultSet);
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if( pWInfo->pOrderBy ){
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tabUsed |= sqlite3WhereExprListUsage(&pWInfo->sMaskSet, pWInfo->pOrderBy);
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}
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for(i=pWInfo->nLevel-1; i>=1; i--){
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WhereTerm *pTerm, *pEnd;
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SrcItem *pItem;
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WhereLoop *pLoop;
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pLoop = pWInfo->a[i].pWLoop;
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pItem = &pWInfo->pTabList->a[pLoop->iTab];
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if( (pItem->fg.jointype & JT_LEFT)==0 ) continue;
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if( (pWInfo->wctrlFlags & WHERE_WANT_DISTINCT)==0
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&& (pLoop->wsFlags & WHERE_ONEROW)==0
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){
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continue;
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}
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if( (tabUsed & pLoop->maskSelf)!=0 ) continue;
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pEnd = pWInfo->sWC.a + pWInfo->sWC.nTerm;
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for(pTerm=pWInfo->sWC.a; pTerm<pEnd; pTerm++){
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if( (pTerm->prereqAll & pLoop->maskSelf)!=0 ){
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if( !ExprHasProperty(pTerm->pExpr, EP_FromJoin)
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|| pTerm->pExpr->iRightJoinTable!=pItem->iCursor
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){
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break;
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}
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}
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}
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if( pTerm<pEnd ) continue;
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WHERETRACE(0xffff, ("-> drop loop %c not used\n", pLoop->cId));
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notReady &= ~pLoop->maskSelf;
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for(pTerm=pWInfo->sWC.a; pTerm<pEnd; pTerm++){
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if( (pTerm->prereqAll & pLoop->maskSelf)!=0 ){
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pTerm->wtFlags |= TERM_CODED;
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}
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}
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if( i!=pWInfo->nLevel-1 ){
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int nByte = (pWInfo->nLevel-1-i) * sizeof(WhereLevel);
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memmove(&pWInfo->a[i], &pWInfo->a[i+1], nByte);
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}
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pWInfo->nLevel--;
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assert( pWInfo->nLevel>0 );
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}
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return notReady;
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}
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/*
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** Generate the beginning of the loop used for WHERE clause processing.
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** The return value is a pointer to an opaque structure that contains
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@ -5111,34 +5201,15 @@ WhereInfo *sqlite3WhereBegin(
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}
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#endif
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/* Attempt to omit tables from the join that do not affect the result.
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** For a table to not affect the result, the following must be true:
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/* Attempt to omit tables from a join that do not affect the result.
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** See the comment on whereOmitNoopJoin() for further information.
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**
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** 1) The query must not be an aggregate.
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** 2) The table must be the RHS of a LEFT JOIN.
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** 3) Either the query must be DISTINCT, or else the ON or USING clause
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** must contain a constraint that limits the scan of the table to
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** at most a single row.
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** 4) The table must not be referenced by any part of the query apart
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** from its own USING or ON clause.
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**
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** For example, given:
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**
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** CREATE TABLE t1(ipk INTEGER PRIMARY KEY, v1);
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** CREATE TABLE t2(ipk INTEGER PRIMARY KEY, v2);
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** CREATE TABLE t3(ipk INTEGER PRIMARY KEY, v3);
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**
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** then table t2 can be omitted from the following:
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**
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** SELECT v1, v3 FROM t1
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** LEFT JOIN t2 ON (t1.ipk=t2.ipk)
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** LEFT JOIN t3 ON (t1.ipk=t3.ipk)
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**
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** or from:
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**
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** SELECT DISTINCT v1, v3 FROM t1
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** LEFT JOIN t2
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** LEFT JOIN t3 ON (t1.ipk=t3.ipk)
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** This query optimization is factored out into a separate "no-inline"
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** procedure to keep the sqlite3WhereBegin() procedure from becoming
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** too large. If sqlite3WhereBegin() becomes too large, that prevents
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** some C-compiler optimizers from in-lining the
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** sqlite3WhereCodeOneLoopStart() procedure, and it is important to
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** in-line sqlite3WhereCodeOneLoopStart() for performance reasons.
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*/
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notReady = ~(Bitmask)0;
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if( pWInfo->nLevel>=2
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@ -5146,49 +5217,11 @@ WhereInfo *sqlite3WhereBegin(
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&& 0==(wctrlFlags & WHERE_AGG_DISTINCT) /* condition (1) above */
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&& OptimizationEnabled(db, SQLITE_OmitNoopJoin)
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){
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int i;
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Bitmask tabUsed = sqlite3WhereExprListUsage(pMaskSet, pResultSet);
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if( sWLB.pOrderBy ){
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tabUsed |= sqlite3WhereExprListUsage(pMaskSet, sWLB.pOrderBy);
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}
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for(i=pWInfo->nLevel-1; i>=1; i--){
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WhereTerm *pTerm, *pEnd;
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SrcItem *pItem;
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pLoop = pWInfo->a[i].pWLoop;
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pItem = &pWInfo->pTabList->a[pLoop->iTab];
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if( (pItem->fg.jointype & JT_LEFT)==0 ) continue;
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if( (wctrlFlags & WHERE_WANT_DISTINCT)==0
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&& (pLoop->wsFlags & WHERE_ONEROW)==0
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){
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continue;
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}
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if( (tabUsed & pLoop->maskSelf)!=0 ) continue;
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pEnd = sWLB.pWC->a + sWLB.pWC->nTerm;
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for(pTerm=sWLB.pWC->a; pTerm<pEnd; pTerm++){
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if( (pTerm->prereqAll & pLoop->maskSelf)!=0 ){
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if( !ExprHasProperty(pTerm->pExpr, EP_FromJoin)
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|| pTerm->pExpr->iRightJoinTable!=pItem->iCursor
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){
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break;
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}
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}
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}
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if( pTerm<pEnd ) continue;
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WHERETRACE(0xffff, ("-> drop loop %c not used\n", pLoop->cId));
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notReady &= ~pLoop->maskSelf;
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for(pTerm=sWLB.pWC->a; pTerm<pEnd; pTerm++){
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if( (pTerm->prereqAll & pLoop->maskSelf)!=0 ){
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pTerm->wtFlags |= TERM_CODED;
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}
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}
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if( i!=pWInfo->nLevel-1 ){
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int nByte = (pWInfo->nLevel-1-i) * sizeof(WhereLevel);
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memmove(&pWInfo->a[i], &pWInfo->a[i+1], nByte);
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}
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pWInfo->nLevel--;
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nTabList--;
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}
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notReady = whereOmitNoopJoin(pWInfo, notReady);
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nTabList = pWInfo->nLevel;
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assert( nTabList>0 );
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}
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#if defined(WHERETRACE_ENABLED)
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if( sqlite3WhereTrace & 0x100 ){ /* Display all terms of the WHERE clause */
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sqlite3DebugPrintf("---- WHERE clause at end of analysis:\n");
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