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Clean up the proper-subset cost adjustment logic to make it more compact

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and easier to read and so that full branch test coverage is more easily
obtained.

FossilOrigin-Name: 9a5d38c79d2482a23bcfbc3ff35ca4fa269c768d
This commit is contained in:
drh 2014-04-18 22:20:31 +00:00
parent 71794dbaeb
commit b355c2cc12
3 changed files with 40 additions and 27 deletions
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12
manifest
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@ -1,5 +1,5 @@
C Add\sthe\sSQLITE_RUNTIME_BYTEORDER\scompile-time\soption\sto\sforce\sSQLite\sto\scheck\nthe\sprocessor\sbyte-order\sat\srun-time.\s\sAdd\sadditional\scompile-time\sbyte\sorder\nchecks\sfor\sARM,\sPPC,\sand\sSPARC.
D 2014-04-18T00:49:29.419
C Clean\sup\sthe\sproper-subset\scost\sadjustment\slogic\sto\smake\sit\smore\scompact\nand\seasier\sto\sread\sand\sso\sthat\sfull\sbranch\stest\scoverage\sis\smore\seasily\nobtained.
D 2014-04-18T22:20:31.054
F Makefile.arm-wince-mingw32ce-gcc d6df77f1f48d690bd73162294bbba7f59507c72f
F Makefile.in 2ef13430cd359f7b361bb863504e227b25cc7f81
F Makefile.linux-gcc 91d710bdc4998cb015f39edf3cb314ec4f4d7e23
@ -291,7 +291,7 @@ F src/vtab.c 21b932841e51ebd7d075e2d0ad1415dce8d2d5fd
F src/wal.c 76e7fc6de229bea8b30bb2539110f03a494dc3a8
F src/wal.h df01efe09c5cb8c8e391ff1715cca294f89668a4
F src/walker.c 11edb74d587bc87b33ca96a5173e3ec1b8389e45
F src/where.c 7614c4383d8b6143558dc349da286d0325704d35
F src/where.c 114b480d3c2eefd9fbc395ee96e03fbd883f418d
F src/whereInt.h 2564055b440e44ebec8b47f237bbccae6719b7af
F test/8_3_names.test ebbb5cd36741350040fd28b432ceadf495be25b2
F test/aggerror.test a867e273ef9e3d7919f03ef4f0e8c0d2767944f2
@ -1160,7 +1160,7 @@ F tool/vdbe_profile.tcl 67746953071a9f8f2f668b73fe899074e2c6d8c1
F tool/warnings-clang.sh f6aa929dc20ef1f856af04a730772f59283631d4
F tool/warnings.sh d1a6de74685f360ab718efda6265994b99bbea01
F tool/win/sqlite.vsix 030f3eeaf2cb811a3692ab9c14d021a75ce41fff
P 9c6961967ae00e563ebe2859eaf2639a79f2cb01
R 1b4cbcab83595d3a8147d0a70e1ae961
P 2c5363873a6f990a0abaacac6303acd46b48befc
R b712e75910761b4771536f725cdc6409
U drh
Z a694f54c65c4a003c92caa29b70309b3
Z e77c4b2dd81e4b608cc5f9bf1e51b6ae

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@ -1 +1 @@
2c5363873a6f990a0abaacac6303acd46b48befc
9a5d38c79d2482a23bcfbc3ff35ca4fa269c768d

53
src/where.c
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@ -3712,18 +3712,36 @@ static void whereInfoFree(sqlite3 *db, WhereInfo *pWInfo){
}
/*
** Return TRUE if the set of WHERE clause terms used by pA is a proper
** subset of the WHERE clause terms used by pB.
** Return TRUE if both of the following are true:
**
** (1) X has the same or lower cost that Y
** (2) X is a proper subset of Y
**
** By "proper subset" we mean that X uses fewer WHERE clause terms
** than Y and that every WHERE clause term used by X is also used
** by Y.
**
** If X is a proper subset of Y then Y is a better choice and ought
** to have a lower cost. This routine returns TRUE when that cost
** relationship is inverted and needs to be adjusted.
*/
static int whereLoopProperSubset(const WhereLoop *pA, const WhereLoop *pB){
static int whereLoopCheaperProperSubset(
const WhereLoop *pX, /* First WhereLoop to compare */
const WhereLoop *pY /* Compare against this WhereLoop */
){
int i, j;
assert( pA->nLTerm<pB->nLTerm ); /* Checked by calling function */
for(j=0, i=pA->nLTerm-1; i>=0 && j>=0; i--){
for(j=pB->nLTerm-1; j>=0; j--){
if( pB->aLTerm[j]==pA->aLTerm[i] ) break;
}
if( pX->nLTerm >= pY->nLTerm ) return 0; /* X is not a subset of Y */
if( pX->rRun >= pY->rRun ){
if( pX->rRun > pY->rRun ) return 0; /* X costs more than Y */
if( pX->nOut > pY->nOut ) return 0; /* X costs more than Y */
}
return j>=0;
for(j=0, i=pX->nLTerm-1; i>=0; i--){
for(j=pY->nLTerm-1; j>=0; j--){
if( pY->aLTerm[j]==pX->aLTerm[i] ) break;
}
if( j<0 ) return 0; /* X not a subset of Y since term X[i] not used by Y */
}
return 1; /* All conditions meet */
}
/*
@ -3745,19 +3763,14 @@ static void whereLoopAdjustCost(const WhereLoop *p, WhereLoop *pTemplate){
for(; p; p=p->pNextLoop){
if( p->iTab!=pTemplate->iTab ) continue;
if( (p->wsFlags & WHERE_INDEXED)==0 ) continue;
if( p->nLTerm<pTemplate->nLTerm
&& (p->rRun<pTemplate->rRun || (p->rRun==pTemplate->rRun &&
p->nOut<=pTemplate->nOut))
&& whereLoopProperSubset(p, pTemplate)
){
if( whereLoopCheaperProperSubset(p, pTemplate) ){
/* Adjust pTemplate cost downward so that it is cheaper than its
** subset p */
pTemplate->rRun = p->rRun;
pTemplate->nOut = p->nOut - 1;
}else
if( p->nLTerm>pTemplate->nLTerm
&& (p->rRun>pTemplate->rRun || (p->rRun==pTemplate->rRun &&
p->nOut>=pTemplate->nOut))
&& whereLoopProperSubset(pTemplate, p)
){
}else if( whereLoopCheaperProperSubset(pTemplate, p) ){
/* Adjust pTemplate cost upward so that it is costlier than p since
** pTemplate is a proper subset of p */
pTemplate->rRun = p->rRun;
pTemplate->nOut = p->nOut + 1;
}