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An initial attempt to implement sqlite3_vtab_distinct().

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FossilOrigin-Name: d571262d2345bb11e71bef395cf078e5d7303b974b38b4e319adda6194ccc1c5
This commit is contained in:
drh
2022-01-22 00:18:01 +00:00
parent 4d7f335e8b
commit ec778d2724
8 changed files with 101 additions and 16 deletions
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28
src/where.c
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@@ -32,6 +32,7 @@ typedef struct HiddenIndexInfo HiddenIndexInfo;
struct HiddenIndexInfo {
WhereClause *pWC; /* The Where clause being analyzed */
Parse *pParse; /* The parsing context */
int eDistinct; /* Value to return from sqlite3_vtab_distinct() */
sqlite3_value *aRhs[1]; /* RHS values for constraints. MUST BE LAST
** because extra space is allocated to hold up
** to nTerm such values */
@@ -1101,15 +1102,15 @@ static SQLITE_NOINLINE void sqlite3ConstructBloomFilter(
** by passing the pointer returned by this function to freeIndexInfo().
*/
static sqlite3_index_info *allocateIndexInfo(
Parse *pParse, /* The parsing context */
WhereInfo *pWInfo, /* The WHERE clause */
WhereClause *pWC, /* The WHERE clause being analyzed */
Bitmask mUnusable, /* Ignore terms with these prereqs */
SrcItem *pSrc, /* The FROM clause term that is the vtab */
ExprList *pOrderBy, /* The ORDER BY clause */
u16 *pmNoOmit /* Mask of terms not to omit */
){
int i, j;
int nTerm;
Parse *pParse = pWInfo->pParse;
struct sqlite3_index_constraint *pIdxCons;
struct sqlite3_index_orderby *pIdxOrderBy;
struct sqlite3_index_constraint_usage *pUsage;
@@ -1119,7 +1120,9 @@ static sqlite3_index_info *allocateIndexInfo(
sqlite3_index_info *pIdxInfo;
u16 mNoOmit = 0;
const Table *pTab;
int eDistinct = 0;
ExprList *pOrderBy = pWInfo->pOrderBy;
assert( pSrc!=0 );
pTab = pSrc->pTab;
assert( pTab!=0 );
@@ -1203,6 +1206,9 @@ static sqlite3_index_info *allocateIndexInfo(
}
if( i==n){
nOrderBy = n;
if( (pWInfo->wctrlFlags & WHERE_DISTINCTBY) ){
eDistinct = 1;
}
}
}
@@ -1225,6 +1231,7 @@ static sqlite3_index_info *allocateIndexInfo(
pIdxInfo->aConstraintUsage = pUsage;
pHidden->pWC = pWC;
pHidden->pParse = pParse;
pHidden->eDistinct = eDistinct;
for(i=j=0, pTerm=pWC->a; i<pWC->nTerm; i++, pTerm++){
u16 op;
if( (pTerm->wtFlags & TERM_OK)==0 ) continue;
@@ -3691,6 +3698,18 @@ int sqlite3_vtab_rhs_value(
return rc;
}
/*
** Return true if ORDER BY clause may be handled as DISTINCT.
*/
int sqlite3_vtab_distinct(sqlite3_index_info *pIdxInfo){
HiddenIndexInfo *pHidden = (HiddenIndexInfo*)&pIdxInfo[1];
assert( pHidden->eDistinct==0
|| pHidden->eDistinct==1
|| pHidden->eDistinct==2 );
return pHidden->eDistinct;
}
/*
** Add all WhereLoop objects for a table of the join identified by
** pBuilder->pNew->iTab. That table is guaranteed to be a virtual table.
@@ -3740,8 +3759,7 @@ static int whereLoopAddVirtual(
pNew = pBuilder->pNew;
pSrc = &pWInfo->pTabList->a[pNew->iTab];
assert( IsVirtual(pSrc->pTab) );
p = allocateIndexInfo(pParse, pWC, mUnusable, pSrc, pBuilder->pOrderBy,
&mNoOmit);
p = allocateIndexInfo(pWInfo, pWC, mUnusable, pSrc, &mNoOmit);
if( p==0 ) return SQLITE_NOMEM_BKPT;
pNew->rSetup = 0;
pNew->wsFlags = WHERE_VIRTUALTABLE;