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Simplifications to the initialization of the sqlite3_index_info structure

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that is used to communicate with virtual table modules.  Avoid adding
unused constraints to the sqlite3_index_info structure.  Extra constraints
are harmless, but might be confusing to people trying to understand the code.

FossilOrigin-Name: 5e6357fc953a955d8ebb5c1fcd72e04e4ae5e8bf5941810015c2fbc50de70535
This commit is contained in:
drh
2019-12-28 13:01:52 +00:00
parent 6411d656aa
commit cfcf4de4a6
3 changed files with 18 additions and 26 deletions
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30
src/where.c
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@@ -605,7 +605,7 @@ static void translateColumnToCopy(
** are no-ops.
*/
#if !defined(SQLITE_OMIT_VIRTUALTABLE) && defined(WHERETRACE_ENABLED)
static void TRACE_IDX_INPUTS(sqlite3_index_info *p){
static void whereTraceIndexInfoInputs(sqlite3_index_info *p){
int i;
if( !sqlite3WhereTrace ) return;
for(i=0; i<p->nConstraint; i++){
@@ -623,7 +623,7 @@ static void TRACE_IDX_INPUTS(sqlite3_index_info *p){
p->aOrderBy[i].desc);
}
}
static void TRACE_IDX_OUTPUTS(sqlite3_index_info *p){
static void whereTraceIndexInfoOutputs(sqlite3_index_info *p){
int i;
if( !sqlite3WhereTrace ) return;
for(i=0; i<p->nConstraint; i++){
@@ -639,8 +639,8 @@ static void TRACE_IDX_OUTPUTS(sqlite3_index_info *p){
sqlite3DebugPrintf(" estimatedRows=%lld\n", p->estimatedRows);
}
#else
#define TRACE_IDX_INPUTS(A)
#define TRACE_IDX_OUTPUTS(A)
#define whereTraceIndexInfoInputs(A)
#define whereTraceIndexInfoOutputs(A)
#endif
#ifndef SQLITE_OMIT_AUTOMATIC_INDEX
@@ -950,23 +950,14 @@ static sqlite3_index_info *allocateIndexInfo(
sqlite3ErrorMsg(pParse, "out of memory");
return 0;
}
/* Initialize the structure. The sqlite3_index_info structure contains
** many fields that are declared "const" to prevent xBestIndex from
** changing them. We have to do some funky casting in order to
** initialize those fields.
*/
pHidden = (struct HiddenIndexInfo*)&pIdxInfo[1];
pIdxCons = (struct sqlite3_index_constraint*)&pHidden[1];
pIdxOrderBy = (struct sqlite3_index_orderby*)&pIdxCons[nTerm];
pUsage = (struct sqlite3_index_constraint_usage*)&pIdxOrderBy[nOrderBy];
*(int*)&pIdxInfo->nConstraint = nTerm;
*(int*)&pIdxInfo->nOrderBy = nOrderBy;
*(struct sqlite3_index_constraint**)&pIdxInfo->aConstraint = pIdxCons;
*(struct sqlite3_index_orderby**)&pIdxInfo->aOrderBy = pIdxOrderBy;
*(struct sqlite3_index_constraint_usage**)&pIdxInfo->aConstraintUsage =
pUsage;
pIdxInfo->nOrderBy = nOrderBy;
pIdxInfo->aConstraint = pIdxCons;
pIdxInfo->aOrderBy = pIdxOrderBy;
pIdxInfo->aConstraintUsage = pUsage;
pHidden->pWC = pWC;
pHidden->pParse = pParse;
for(i=j=0, pTerm=pWC->a; i<pWC->nTerm; i++, pTerm++){
@@ -1026,6 +1017,7 @@ static sqlite3_index_info *allocateIndexInfo(
j++;
}
pIdxInfo->nConstraint = j;
for(i=0; i<nOrderBy; i++){
Expr *pExpr = pOrderBy->a[i].pExpr;
pIdxOrderBy[i].iColumn = pExpr->iColumn;
@@ -1056,9 +1048,9 @@ static int vtabBestIndex(Parse *pParse, Table *pTab, sqlite3_index_info *p){
sqlite3_vtab *pVtab = sqlite3GetVTable(pParse->db, pTab)->pVtab;
int rc;
TRACE_IDX_INPUTS(p);
whereTraceIndexInfoInputs(p);
rc = pVtab->pModule->xBestIndex(pVtab, p);
TRACE_IDX_OUTPUTS(p);
whereTraceIndexInfoOutputs(p);
if( rc!=SQLITE_OK && rc!=SQLITE_CONSTRAINT ){
if( rc==SQLITE_NOMEM ){