Unexpected out of memory error for valid query

[vitaliyb1]

Priority:Critical

Hi Marios,

For perfectly valid query

select c3.* from parent c1, child c2, grandchild c3 where c1.rownum=5 and c2.base=c1.child_id and c3.base=c2.child_id

I receive an error:

Error in preparation of query: error no 7
Extended error code 7. Extended error message: out of memory
Extended error message: out of memory

I hacked best_index (see vitaliyb tag below) to stop getting that error for this and some other queries:

int best_index_vtable(sqlite3_vtab pVtab,
sqlite3_index_info *pInfo) {
picoQLTable *st=(picoQLTable *)pVtab;
int re;
st->toOpen = 1;
re = toOpen(pVtab);
if (re)
return re;
/ No constraint no setting up. _/
if (pInfo->nConstraint > 0) {
int nCol;
int nidxLen = pInfo->nConstraint_7 + 1;
int i, j = 0, counter = 0, score = 0;
char nidxStr = (char)malloc( nidxLen );
memset(nidxStr, 0, sizeof(nidxStr));
assert(pInfo->idxStr == 0);
for (i = 0; i < pInfo->nConstraint; i++){
struct sqlite3_index_constraint *pCons = &pInfo->aConstraint[i];
if (pCons->usable == 0)
continue;
nCol = pCons->iColumn;
if (equals(st->azColumn[nCol], "base"))
score += 2;
else if (equals(st->azColumn[nCol], "rownum"))
score += 1;
}
order_constraints(score, &j, &counter, nidxStr);
for (i = 0; i < pInfo->nConstraint; i++) {
struct sqlite3_index_constraint *pCons =
&pInfo->aConstraint[i];
if (pCons->usable == 0)
continue;
nCol = pCons->iColumn;
if (equals(st->azColumn[nCol], "base")) {
pInfo->aConstraintUsage[i].argvIndex = 1;
} else if (equals(st->azColumn[nCol], "rownum")) {
if (score > 2)
pInfo->aConstraintUsage[i].argvIndex = 2;
else
pInfo->aConstraintUsage[i].argvIndex = 1;
} else {
pInfo->aConstraintUsage[i].argvIndex = counter++;
}
eval_constraint(pCons->op, st->azColumn[nCol], nCol,
score, nidxStr, nidxLen);
pInfo->aConstraintUsage[i].omit = 1;
}
pInfo->needToFreeIdxStr = 1;
if ((((int)strlen(nidxStr)) > 0) &&
0 == (pInfo->idxStr =
sqlite3_mprintf("%s", nidxStr)))

  free( nidxStr );

  // vitaliyb, 09/14/16 ///
  // return SQLITE_NOMEM; 
  return SQLITE_OK;
  /////////////////////////

}
return SQLITE_OK;
}

Best regards,
Vitaly