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Rework this changes so that instead of setting the WhereTerm.truthProb when

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a term is seen to be of low selectivity, it merely sets a new flag
(the TERM_HIGHTRUTH flag) which causes whereLoopOutputAdjust() to ignore
that term.

FossilOrigin-Name: 4558163b6a525990f0f1b6629dbb76daf49bcaf1ddbaf0c50fe05ce9ee480ff8
This commit is contained in:
drh 2020-02-24 16:46:08 +00:00
parent 35d3cb80c4
commit f06cdde2cf
4 changed files with 29 additions and 21 deletions
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14
manifest
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@ -1,5 +1,5 @@
C Disable\sthe\snew\sanalyzeG.test\smodule\sif\snot\sbuilding\swith\sSTAT4.
D 2020-02-24T13:35:34.777
C Rework\sthis\schanges\sso\sthat\sinstead\sof\ssetting\sthe\sWhereTerm.truthProb\swhen\na\sterm\sis\sseen\sto\sbe\sof\slow\sselectivity,\sit\smerely\ssets\sa\snew\sflag\n(the\sTERM_HIGHTRUTH\sflag)\swhich\scauses\swhereLoopOutputAdjust()\sto\signore\nthat\sterm.
D 2020-02-24T16:46:08.182
F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@ -617,8 +617,8 @@ F src/vxworks.h d2988f4e5a61a4dfe82c6524dd3d6e4f2ce3cdb9
F src/wal.c 697424314e40d99f93f548c7bfa526c10e87f4bdf64d5a76a96b999dd7133ebc
F src/wal.h 606292549f5a7be50b6227bd685fa76e3a4affad71bb8ac5ce4cb5c79f6a176a
F src/walker.c a137468bf36c92e64d2275caa80c83902e3a0fc59273591b96c6416d3253d05d
F src/where.c 44695e878a287d8c1d4976e2e85bea29994facec3972beb7ca22437d62cda6a5
F src/whereInt.h 94e3aadcf43b4d16279182d147c9e4f8ef6ed5a5bd1ecc021639c29336b0a3eb
F src/where.c 3b8c9bd013eb0736e16f60bdc109e83337ef99513a3aff5f16ddac036e6c277e
F src/whereInt.h 6b874aa15f94e43a2cec1080be64d955b04deeafeac90ffb5d6975c0d511be3c
F src/wherecode.c f5df56e395ade2240cabb2d39500c681bd29f8cc0636c3301c4996ad160df94d
F src/whereexpr.c 264d58971eaf8256eb5b0917bcd7fc7a1f1109fdda183a8382308a1b18a2dce7
F src/window.c f8ba2ee12a19b51d3ba42c16277c74185ee9215306bc0d5a03974ade8b5bc98f
@ -1859,7 +1859,7 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
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R 2f59a601b560c09f0f628a3935395fd4
U drh
Z 9cae8ff3aee64bed711ead2769a79514
Z 144378d74bf58f80a9e1ca77433de7e1

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@ -1 +1 @@
4a9d3005769e0398183b03a3e132e3946b9d1c48073af2e0559d7beeac3245c0
4558163b6a525990f0f1b6629dbb76daf49bcaf1ddbaf0c50fe05ce9ee480ff8

29
src/where.c
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@ -2298,14 +2298,16 @@ static void whereLoopOutputAdjust(
/* In the absence of explicit truth probabilities, use heuristics to
** guess a reasonable truth probability. */
pLoop->nOut--;
if( pTerm->eOperator&(WO_EQ|WO_IS) ){
if( (pTerm->eOperator&(WO_EQ|WO_IS))!=0
&& (pTerm->wtFlags & TERM_HIGHTRUTH)==0 /* tag-20200224-1 */
){
Expr *pRight = pTerm->pExpr->pRight;
int k = 0;
testcase( pTerm->pExpr->op==TK_IS );
if( sqlite3ExprIsInteger(pRight, &k) && k>=(-1) && k<=1 ){
k = 10;
}else{
k = 20; /* Keep the "20" value in sync. See tag-20200222-1 */
k = 20;
}
if( iReduce<k ){
pTerm->wtFlags |= TERM_HEURTRUTH;
@ -2660,23 +2662,23 @@ static int whereLoopAddBtreeIndex(
if( nOut ){
pNew->nOut = sqlite3LogEst(nOut);
if( nEq==1
&& pTerm->truthProb>0
/* TUNING: Adjust truthProb from the default heuristic only if the
** probability is close to 1.0. The "20" constant is copied from
** the heuristic at tag-20200222-1. Keep values in sync */
&& pNew->nOut+20 > pProbe->aiRowLogEst[0]
/* TUNING: Mark terms as "low selectivity" if they seem likely
** to be true for half or more of the rows in the table.
** See tag-202002240-1 */
&& pNew->nOut+10 > pProbe->aiRowLogEst[0]
){
#if WHERETRACE_ENABLED /* 0x01 */
if( sqlite3WhereTrace & 0x01 ){
sqlite3DebugPrintf("Update truthProb from %d to %d:\n",
pTerm->truthProb, pNew->nOut - pProbe->aiRowLogEst[0]);
sqlite3DebugPrintf(
"STAT4 determines term has low selectivity:\n");
sqlite3WhereTermPrint(pTerm, 999);
}
#endif
pTerm->truthProb = pNew->nOut - pProbe->aiRowLogEst[0];
pTerm->wtFlags |= TERM_HIGHTRUTH;
if( pTerm->wtFlags & TERM_HEURTRUTH ){
/* If the old heuristic truthProb was previously used, signal
** that all loops will need to be recomputed */
/* If the term has previously been used with an assumption of
** higher selectivity, then set the flag to rerun the
** loop computations. */
pBuilder->bldFlags2 |= SQLITE_BLDF2_2NDPASS;
}
}
@ -4894,7 +4896,8 @@ WhereInfo *sqlite3WhereBegin(
if( sWLB.bldFlags2 & SQLITE_BLDF2_2NDPASS ){
WHERETRACE_ALL_LOOPS(pWInfo, sWLB.pWC);
WHERETRACE(0xffff,
("**** Redo all loop computations due to truthProb changes ****\n"));
("**** Redo all loop computations due to"
" TERM_HIGHTRUTH changes ****\n"));
while( pWInfo->pLoops ){
WhereLoop *p = pWInfo->pLoops;
pWInfo->pLoops = p->pNextLoop;

5
src/whereInt.h
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@ -292,6 +292,11 @@ struct WhereTerm {
#define TERM_IS 0x0800 /* Term.pExpr is an IS operator */
#define TERM_VARSELECT 0x1000 /* Term.pExpr contains a correlated sub-query */
#define TERM_HEURTRUTH 0x2000 /* Heuristic truthProb used */
#ifdef SQLITE_ENABLE_STAT4
# define TERM_HIGHTRUTH 0x4000 /* Term excludes few rows */
#else
# define TERM_HIGHTRUTH 0 /* Only used with STAT4 */
#endif
/*
** An instance of the WhereScan object is used as an iterator for locating