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Enhance the xBestIndex interface of virtual table so that if the xBestIndex

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method returns SQLITE_CONSTRAINT then that particular combination of
constraints is considered unusable and does not participate further in
query planning.

FossilOrigin-Name: 684013cef6bfcfd920a4aec645df9f5d41ace8b34e75fca61759c1b4f82cc89e
This commit is contained in:
drh
2018-11-16 13:56:15 +00:00
parent eabbf37fae
commit 32dcc847b5
5 changed files with 74 additions and 46 deletions
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ext/misc/fileio.c
+37 -11
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@@ -846,27 +846,53 @@ static int fsdirBestIndex(
sqlite3_index_info *pIdxInfo
){
int i; /* Loop over constraints */
int idx4 = -1; /* Index in pIdxInfo->aConstraint of PATH= */
int idx5 = -1; /* Index in pIdxInfo->aConstraint of DIR= */
int idxPath = -1; /* Index in pIdxInfo->aConstraint of PATH= */
int idxDir = -1; /* Index in pIdxInfo->aConstraint of DIR= */
int seenPath = 0; /* True if an unusable PATH= constraint is seen */
int seenDir = 0; /* True if an unusable DIR= constraint is seen */
const struct sqlite3_index_constraint *pConstraint;
(void)tab;
pConstraint = pIdxInfo->aConstraint;
for(i=0; i<pIdxInfo->nConstraint; i++, pConstraint++){
if( pConstraint->op!=SQLITE_INDEX_CONSTRAINT_EQ ) continue;
if( pConstraint->iColumn==4 && pConstraint->usable ) idx4 = i;
if( pConstraint->iColumn==5 ) idx5 = i;
switch( pConstraint->iColumn ){
case FSDIR_COLUMN_PATH: {
if( pConstraint->usable ){
idxPath = i;
seenPath = 0;
}else if( idxPath<0 ){
seenPath = 1;
}
break;
}
case FSDIR_COLUMN_DIR: {
if( pConstraint->usable ){
idxDir = i;
seenDir = 0;
}else if( idxDir<0 ){
seenDir = 1;
}
break;
}
}
}
if( seenPath || seenDir ){
/* If input parameters are unusable, disallow this plan */
return SQLITE_CONSTRAINT;
}
if( idx4<0 || (idx5>=0 && pIdxInfo->aConstraint[idx5].usable==0) ){
if( idxPath<0 ){
pIdxInfo->idxNum = 0;
pIdxInfo->estimatedCost = (double)(((sqlite3_int64)1) << 60);
/* The pIdxInfo->estimatedCost should have been initialized to a huge
** number. Leave it unchanged. */
pIdxInfo->estimatedRows = 0x7fffffff;
}else{
pIdxInfo->aConstraintUsage[idx4].omit = 1;
pIdxInfo->aConstraintUsage[idx4].argvIndex = 1;
if( idx5>=0 ){
pIdxInfo->aConstraintUsage[idx5].omit = 1;
pIdxInfo->aConstraintUsage[idx5].argvIndex = 2;
pIdxInfo->aConstraintUsage[idxPath].omit = 1;
pIdxInfo->aConstraintUsage[idxPath].argvIndex = 1;
if( idxDir>=0 ){
pIdxInfo->aConstraintUsage[idxDir].omit = 1;
pIdxInfo->aConstraintUsage[idxDir].argvIndex = 2;
pIdxInfo->idxNum = 2;
pIdxInfo->estimatedCost = 10.0;
}else{