/* * Detect whether a tsquery boolean expression requires any positive matches * to values shown in the tsquery. * * This is needed to know whether a GIN index search requires full index scan. * For example, 'x & !y' requires a match of x, so it's sufficient to scan * entries for x; but 'x | !y' could match rows containing neither x nor y. */ bool tsquery_requires_match(QueryItem *curitem) { /* since this function recurses, it could be driven to stack overflow */ check_stack_depth(); if (curitem->type == QI_VAL) return true; switch (curitem->qoperator.oper) { case OP_NOT: /* * Assume there are no required matches underneath a NOT. For * some cases with nested NOTs, we could prove there's a required * match, but it seems unlikely to be worth the trouble. */ return false; case OP_AND: /* If either side requires a match, we're good */ if (tsquery_requires_match(curitem + curitem->qoperator.left)) return true; else return tsquery_requires_match(curitem + 1); case OP_OR: /* Both sides must require a match */ if (tsquery_requires_match(curitem + curitem->qoperator.left)) return tsquery_requires_match(curitem + 1); else return false; default: elog(ERROR, "unrecognized operator: %d", curitem->qoperator.oper); } /* not reachable, but keep compiler quiet */ return false; }
Datum gin_extract_tsquery(PG_FUNCTION_ARGS) { TSQuery query = PG_GETARG_TSQUERY(0); int32 *nentries = (int32 *) PG_GETARG_POINTER(1); /* StrategyNumber strategy = PG_GETARG_UINT16(2); */ bool **ptr_partialmatch = (bool **) PG_GETARG_POINTER(3); Pointer **extra_data = (Pointer **) PG_GETARG_POINTER(4); /* bool **nullFlags = (bool **) PG_GETARG_POINTER(5); */ int32 *searchMode = (int32 *) PG_GETARG_POINTER(6); Datum *entries = NULL; *nentries = 0; if (query->size > 0) { QueryItem *item = GETQUERY(query); int32 i, j; bool *partialmatch; int *map_item_operand; /* * If the query doesn't have any required positive matches (for * instance, it's something like '! foo'), we have to do a full index * scan. */ if (tsquery_requires_match(item)) *searchMode = GIN_SEARCH_MODE_DEFAULT; else *searchMode = GIN_SEARCH_MODE_ALL; /* count number of VAL items */ j = 0; for (i = 0; i < query->size; i++) { if (item[i].type == QI_VAL) j++; } *nentries = j; entries = (Datum *) palloc(sizeof(Datum) * j); partialmatch = *ptr_partialmatch = (bool *) palloc(sizeof(bool) * j); /* * Make map to convert item's number to corresponding operand's (the * same, entry's) number. Entry's number is used in check array in * consistent method. We use the same map for each entry. */ *extra_data = (Pointer *) palloc(sizeof(Pointer) * j); map_item_operand = (int *) palloc0(sizeof(int) * query->size); /* Now rescan the VAL items and fill in the arrays */ j = 0; for (i = 0; i < query->size; i++) { if (item[i].type == QI_VAL) { QueryOperand *val = &item[i].qoperand; text *txt; txt = cstring_to_text_with_len(GETOPERAND(query) + val->distance, val->length); entries[j] = PointerGetDatum(txt); partialmatch[j] = val->prefix; (*extra_data)[j] = (Pointer) map_item_operand; map_item_operand[i] = j; j++; } } } PG_FREE_IF_COPY(query, 0); PG_RETURN_POINTER(entries); }