Fix table dropping in non-default MotherDuck database

include/pgduckdb/pgduckdb_ruleutils.h

@@ -3,3 +3,4 @@
 char *pgduckdb_relation_name(Oid relid);
 char *pgduckdb_function_name(Oid function_oid);
 char *pgduckdb_get_tabledef(Oid relation_id);
+const char *pgduckdb_db_and_schema(const char *postgres_schema_name, bool is_duckdb_table);

src/pgduckdb_ddl.cpp

@@ -309,12 +309,12 @@ duckdb_drop_trigger(PG_FUNCTION_ARGS) {
 	int ret = SPI_exec(R"(
 		DELETE FROM duckdb.tables
 		USING (
-			SELECT objid, object_name, object_identity
+			SELECT objid, schema_name, object_name
 			FROM pg_catalog.pg_event_trigger_dropped_objects()
 			WHERE object_type = 'table'
 		) objs
 		WHERE relid = objid
-		RETURNING objs.object_identity
+		RETURNING objs.schema_name, objs.object_name
 		)",
 	                   0);
 
@@ -346,9 +346,11 @@ duckdb_drop_trigger(PG_FUNCTION_ARGS) {
 			}
 			HeapTuple tuple = SPI_tuptable->vals[proc];
 
-			char *object_identity = SPI_getvalue(tuple, SPI_tuptable->tupdesc, 1);
-			// TODO: Handle std::string creation in a safe way for allocation failures
-			pgduckdb::DuckDBQueryOrThrow(*connection, "DROP TABLE IF EXISTS " + std::string(object_identity));
+			char *postgres_schema_name = SPI_getvalue(tuple, SPI_tuptable->tupdesc, 1);
+			char *table_name = SPI_getvalue(tuple, SPI_tuptable->tupdesc, 2);
+			char *drop_query = psprintf("DROP TABLE %s.%s", pgduckdb_db_and_schema(postgres_schema_name, true),
+			                            quote_identifier(table_name));
+			pgduckdb::DuckDBQueryOrThrow(*connection, drop_query);
 		}
 	}
 
@@ -392,7 +394,7 @@ duckdb_drop_trigger(PG_FUNCTION_ARGS) {
 		}
 		char *table_name = SPI_getvalue(tuple, SPI_tuptable->tupdesc, 2);
 		pgduckdb::DuckDBQueryOrThrow(*connection,
-		                             std::string("DROP TABLE IF EXISTS pg_temp.main.") + quote_identifier(table_name));
+		                             std::string("DROP TABLE pg_temp.main.") + quote_identifier(table_name));
 		temporary_duckdb_tables.erase(relid);
 	}
 

src/pgduckdb_ruleutils.cpp

@@ -32,7 +32,12 @@ pgduckdb_function_name(Oid function_oid) {
 	return psprintf("system.main.%s", quote_identifier(func_name));
 }
 
-static List *
+/*
+ * Given a postgres schema name, this returns a list of two elements: the first
+ * is the DuckDB database name and the second is the duckdb schema name. These
+ * are not escaped yet.
+ */
+List *
 GetDuckdbCatalogAndSchema(const char *postgres_schema_name) {
 	if (strncmp("ddb$", postgres_schema_name, 4) != 0) {
 		auto dbname = pgduckdb::DuckDBManager::Get().GetDefaultDBName().c_str();
@@ -79,19 +84,22 @@ GetDuckdbCatalogAndSchema(const char *postgres_schema_name) {
 	return list_make2(db_name.data, schema_name.data);
 }
 
-static const char *
-DuckdbCatalogAndSchemaString(Form_pg_class relation) {
-	if (relation->relam == pgduckdb::DuckdbTableAmOid() && relation->relpersistence == RELPERSISTENCE_TEMP) {
+/*
+ * Returns the fully qualified DuckDB database and schema. The schema and
+ * database are quoted if necessary.
+ */
+const char *
+pgduckdb_db_and_schema(const char *postgres_schema_name, bool is_duckdb_table) {
+	if (is_duckdb_table && strcmp("pg_temp", postgres_schema_name) == 0) {
 		return "pg_temp.main";
 	}
-
-	const char *postgres_schema_name = get_namespace_name_or_temp(relation->relnamespace);
 	const char *db_name;
 	const char *schema_name;
-	if (relation->relam == pgduckdb::DuckdbTableAmOid()) {
+	if (is_duckdb_table) {
 		List *db_and_schema = GetDuckdbCatalogAndSchema(postgres_schema_name);
 		db_name = (const char *)linitial(db_and_schema);
 		schema_name = (const char *)lsecond(db_and_schema);
+		return psprintf("%s.%s", quote_identifier(db_name), quote_identifier(schema_name));
 	} else {
 		db_name = "pgduckdb";
 		schema_name = postgres_schema_name;
@@ -112,7 +120,8 @@ pgduckdb_relation_name(Oid relation_oid) {
 		elog(ERROR, "cache lookup failed for relation %u", relation_oid);
 	Form_pg_class relation = (Form_pg_class)GETSTRUCT(tp);
 	const char *relname = NameStr(relation->relname);
-	const char *db_and_schema = DuckdbCatalogAndSchemaString(relation);
+	const char *postgres_schema_name = get_namespace_name_or_temp(relation->relnamespace);
+	const char *db_and_schema = pgduckdb_db_and_schema(postgres_schema_name, pgduckdb::IsDuckdbTable(relation));
 
 	char *result = psprintf("%s.%s", db_and_schema, quote_identifier(relname));
 
@@ -137,7 +146,8 @@ char *
 pgduckdb_get_tabledef(Oid relation_oid) {
 	Relation relation = relation_open(relation_oid, AccessShareLock);
 	const char *relation_name = pgduckdb_relation_name(relation_oid);
-	const char *db_and_schema = DuckdbCatalogAndSchemaString(relation->rd_rel);
+	const char *postgres_schema_name = get_namespace_name_or_temp(relation->rd_rel->relnamespace);
+	const char *db_and_schema = pgduckdb_db_and_schema(postgres_schema_name, pgduckdb::IsDuckdbTable(relation));
 
 	StringInfoData buffer;
 	initStringInfo(&buffer);