Function bson_query_match

pg_documentdb/src/query/query_operator.c:285–365

* bson_query_match is a lazy, inefficient implementation of the @@ * operator and bson_query_match, used only when we cannot replace it in the planner hook. */

 * operator and bson_query_match, used only when we cannot replace it in the planner hook.
 */
Datum
bson_query_match(PG_FUNCTION_ARGS)
{
	pgbson *document = PG_GETARG_PGBSON(0);
	pgbson *query = PG_GETARG_PGBSON(1);

	Const *documentConst = MakeBsonConst(document);
	Const *queryConst = MakeBsonConst(query);

	ereport(NOTICE, (errmsg("using bson_query_match implementation")));

	ReplaceBsonQueryOperatorsContext context;
	memset(&context, 0, sizeof(context));

	Node *quals = NULL;
	if (PG_NARGS() == 2)
	{
		/* Expand the @@ operator into regular BSON operators */
		OpExpr *queryExpr = makeNode(OpExpr);
		queryExpr->opno = BsonQueryOperatorId();
		queryExpr->opfuncid = BsonQueryMatchFunctionId();
		queryExpr->inputcollid = InvalidOid;
		queryExpr->opresulttype = BsonTypeId();
		queryExpr->args = list_make2(documentConst, queryConst);
		queryExpr->location = -1;

		quals = ReplaceBsonQueryOperatorsMutator((Node *) queryExpr, &context);
	}
	else if (PG_NARGS() == 4)
	{
		/* TODO: Remove after v0.110 when function has only STRICT forms */
		if (PG_ARGISNULL(0) && PG_ARGISNULL(1))
		{
			PG_RETURN_NULL();
		}

		Const *variableSpecConst = NULL;
		if (PG_ARGISNULL(2))
		{
			variableSpecConst = MakeBsonConst(PgbsonInitEmpty());
		}
		else
		{
			pgbson *variableSpecBson = PG_GETARG_PGBSON(2);
			variableSpecConst = MakeBsonConst(variableSpecBson);
		}

		Const *collationConst = NULL;
		if (PG_ARGISNULL(3))
		{
			collationConst = makeConst(TEXTOID, -1, InvalidOid, -1,
									   CStringGetDatum(""), false, false);
		}
		else
		{
			Datum collationDatum = CStringGetDatum(PG_GETARG_CSTRING(3));
			collationConst = makeConst(TEXTOID, -1, InvalidOid, -1, collationDatum,
									   false, false);