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Do not activate the truthProb adjustment mechanism if the truth probability

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is less than the heuristic value, as there could be correlations unknown to
stat4.  Also add additional tracing output to make truthProb adjustments more
visible.

FossilOrigin-Name: c535fea147ce5c6e4aab25d3c85a3f53a7364c5b5ee10fb6d393c5911a02be7e
This commit is contained in:
drh
2020-02-22 18:27:48 +00:00
parent 5c19346451
commit cea1951e80
3 changed files with 40 additions and 23 deletions
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47
src/where.c
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@@ -2305,7 +2305,7 @@ static void whereLoopOutputAdjust(
if( sqlite3ExprIsInteger(pRight, &k) && k>=(-1) && k<=1 ){
k = 10;
}else{
k = 20;
k = 20; /* Keep the "20" value in sync. See tag-20200222-1 */
}
if( iReduce<k ){
pTerm->wtFlags |= TERM_HEURTRUTH;
@@ -2659,7 +2659,13 @@ static int whereLoopAddBtreeIndex(
if( rc!=SQLITE_OK ) break; /* Jump out of the pTerm loop */
if( nOut ){
pNew->nOut = sqlite3LogEst(nOut);
if( nEq==1 && pTerm->truthProb>0 ){
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]
){
#if WHERETRACE_ENABLED /* 0x01 */
if( sqlite3WhereTrace & 0x01 ){
sqlite3DebugPrintf("Update truthProb from %d to %d:\n",
@@ -4555,6 +4561,28 @@ static int exprIsDeterministic(Expr *p){
return w.eCode;
}
#ifdef WHERETRACE_ENABLED
/*
** Display all WhereLoops in pWInfo
*/
static void showAllWhereLoops(WhereInfo *pWInfo, WhereClause *pWC){
if( sqlite3WhereTrace ){ /* Display all of the WhereLoop objects */
WhereLoop *p;
int i;
static const char zLabel[] = "0123456789abcdefghijklmnopqrstuvwyxz"
"ABCDEFGHIJKLMNOPQRSTUVWYXZ";
for(p=pWInfo->pLoops, i=0; p; p=p->pNextLoop, i++){
p->cId = zLabel[i%(sizeof(zLabel)-1)];
sqlite3WhereLoopPrint(p, pWC);
}
}
}
# define WHERETRACE_ALL_LOOPS(W,C) showAllWhereLoops(W,C)
#else
# define WHERETRACE_ALL_LOOPS(W,C)
#endif
/*
** Generate the beginning of the loop used for WHERE clause processing.
** The return value is a pointer to an opaque structure that contains
@@ -4864,6 +4892,7 @@ WhereInfo *sqlite3WhereBegin(
** then we need to rerun the whole loop building process so that all
** loops will be built using the revised truthProb values. */
if( sWLB.bldFlags2 & SQLITE_BLDF2_2NDPASS ){
WHERETRACE_ALL_LOOPS(pWInfo, sWLB.pWC);
WHERETRACE(0xffff,
("**** Redo all loop computations due to truthProb changes ****\n"));
while( pWInfo->pLoops ){
@@ -4875,19 +4904,7 @@ WhereInfo *sqlite3WhereBegin(
if( rc ) goto whereBeginError;
}
#endif
#ifdef WHERETRACE_ENABLED
if( sqlite3WhereTrace ){ /* Display all of the WhereLoop objects */
WhereLoop *p;
int i;
static const char zLabel[] = "0123456789abcdefghijklmnopqrstuvwyxz"
"ABCDEFGHIJKLMNOPQRSTUVWYXZ";
for(p=pWInfo->pLoops, i=0; p; p=p->pNextLoop, i++){
p->cId = zLabel[i%(sizeof(zLabel)-1)];
sqlite3WhereLoopPrint(p, sWLB.pWC);
}
}
#endif
WHERETRACE_ALL_LOOPS(pWInfo, sWLB.pWC);
wherePathSolver(pWInfo, 0);
if( db->mallocFailed ) goto whereBeginError;