From: drh <drh@noemail.net>
Date: Fri, 1 Mar 2019 18:07:05 +0000 (+0000)
Subject: In a query that uses a partial index, the expression that is the WHERE clause
X-Git-Tag: version-3.28.0~141
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=b531aa8fd9ca317c1ce586d1156c6c084a734264;p=thirdparty%2Fsqlite.git

In a query that uses a partial index, the expression that is the WHERE clause
of the partial index must always be true.  Use this fact to avoid evaluating
identical terms in the WHERE clause of the query.

FossilOrigin-Name: 9b2879629c34fc0a8e99d94648903eb93aabbc7a3682c80cb7382f9a9ca5ffb7
---

diff --git a/manifest b/manifest
index e2da2af99e..1191584f39 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Add\sthe\s".parameter"\scommand\sto\sthe\sCLI.
-D 2019-02-28T20:10:52.766
+C In\sa\squery\sthat\suses\sa\spartial\sindex,\sthe\sexpression\sthat\sis\sthe\sWHERE\sclause\nof\sthe\spartial\sindex\smust\salways\sbe\strue.\s\sUse\sthis\sfact\sto\savoid\sevaluating\nidentical\sterms\sin\sthe\sWHERE\sclause\sof\sthe\squery.
+D 2019-03-01T18:07:05.251
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F Makefile.in 1ad7263f38329c0ecea543c80f30af839ee714ea77fc391bf1a3fbb919a5b6b5
@@ -602,7 +602,7 @@ F src/wal.h 606292549f5a7be50b6227bd685fa76e3a4affad71bb8ac5ce4cb5c79f6a176a
 F src/walker.c 7607f1a68130c028255d8d56094ea602fc402c79e1e35a46e6282849d90d5fe4
 F src/where.c 8a207cb2ca6b99e1edb1e4bbff9b0504385a759cbf66180d1deb34d80ca4b799
 F src/whereInt.h 5f14db426ca46a83eabab1ae9aa6d4b8f27504ad35b64c290916289b1ddb2e88
-F src/wherecode.c 061848646cc46a137d9038e47e666a955b3b2a1b458365eeed76b004c0053f3b
+F src/wherecode.c ce7b21e1be2b981d62683fc59c4ca73a04a7ff2f1ebec23d41baf2da2349afd6
 F src/whereexpr.c 36b47f7261d6b6f1a72d774c113b74beddf6745aba1018e64b196e29db233442
 F src/window.c df2456386e0b1553a8d1fcf3a0ddc4c058fe2c650ea8c74b6bf8862082ddafc9
 F test/8_3_names.test ebbb5cd36741350040fd28b432ceadf495be25b2
@@ -1805,7 +1805,7 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P c7f70b6d96338dba201e005104e7f7148c1a8cd767ab05e35b44617c4c797bc5
-R 2fecd2e603ada3a0c6460ef11e6e9c28
+P 1f9fa58541dc974989eee9c9a5d453956f7dbcf42965ece2db2cb5dee3f3f5e2
+R 999cfe5c6c09ddc9e9ba3498e400f74c
 U drh
-Z f7dd879e1ba76ea61ec7d6d44725ec74
+Z 0f8a04d58b07ebfff6d09b88278bd01c
diff --git a/manifest.uuid b/manifest.uuid
index 91cf4ac998..5f1016277a 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-1f9fa58541dc974989eee9c9a5d453956f7dbcf42965ece2db2cb5dee3f3f5e2
\ No newline at end of file
+9b2879629c34fc0a8e99d94648903eb93aabbc7a3682c80cb7382f9a9ca5ffb7
\ No newline at end of file
diff --git a/src/wherecode.c b/src/wherecode.c
index 79189386b6..758d6b5eec 100644
--- a/src/wherecode.c
+++ b/src/wherecode.c
@@ -1159,6 +1159,34 @@ static void whereIndexExprTrans(
   }
 }
 
+/*
+** The pTruth expression is always tree because it is the WHERE clause
+** a partial index that is driving a query loop.  Look through all of the
+** WHERE clause terms on the query, and if any of those terms must be
+** true because pTruth is true, then mark those WHERE clause terms as
+** coded.
+*/
+static void whereApplyPartialIndexConstraints(
+  Expr *pTruth,
+  int iTabCur,
+  WhereClause *pWC
+){
+  int i;
+  WhereTerm *pTerm;
+  while( pTruth->op==TK_AND ){
+    whereApplyPartialIndexConstraints(pTruth->pLeft, iTabCur, pWC);
+    pTruth = pTruth->pRight;
+  }
+  for(i=0, pTerm=pWC->a; i<pWC->nTerm; i++, pTerm++){
+    Expr *pExpr;
+    if( pTerm->wtFlags & TERM_CODED ) continue;
+    pExpr = pTerm->pExpr;
+    if( sqlite3ExprCompare(0, pExpr, pTruth, iTabCur)==0 ){
+      pTerm->wtFlags |= TERM_CODED;
+    }
+  }
+}
+
 /*
 ** Generate code for the start of the iLevel-th loop in the WHERE clause
 ** implementation described by pWInfo.
@@ -1768,6 +1796,14 @@ Bitmask sqlite3WhereCodeOneLoopStart(
       whereIndexExprTrans(pIdx, iCur, iIdxCur, pWInfo);
     }
 
+    /* If a partial index is driving the loop, try to eliminate WHERE clause
+    ** terms from the query that must be true due to the WHERE clause of
+    ** the partial index
+    */
+    if( pIdx->pPartIdxWhere ){
+      whereApplyPartialIndexConstraints(pIdx->pPartIdxWhere, iCur, pWC);
+    }
+
     /* Record the instruction used to terminate the loop. */
     if( pLoop->wsFlags & WHERE_ONEROW ){
       pLevel->op = OP_Noop;