Drop MD tables when disabled

Author: Y--

src/pgduckdb_background_worker.cpp

@@ -42,6 +42,7 @@ extern "C" {
 #include "catalog/namespace.h"
 #include "catalog/pg_namespace.h"
 #include "catalog/pg_extension.h"
+#include "catalog/pg_foreign_server.h"
 #include "utils/acl.h"
 #include "utils/guc.h"
 #include "utils/memutils.h"
@@ -918,7 +919,7 @@ CreateSchemaIfNotExists(const char *postgres_schema_name, bool is_default_db) {
 	if (!is_default_db) {
 		/*
 		 * For ddb$ schemas we need to record a dependency between the schema
-		 * and the extension, so that DROP EXTENSION also drops these schemas.
+		 * and the FDW, so that DROP SERVER motherduck also drops these schemas.
 		 */
 		schema_oid = get_namespace_oid(postgres_schema_name, true);
 		if (schema_oid == InvalidOid) {
@@ -932,12 +933,12 @@ CreateSchemaIfNotExists(const char *postgres_schema_name, bool is_default_db) {
 		    .objectId = schema_oid,
 		    .objectSubId = 0,
 		};
-		ObjectAddress extension_address = {
-		    .classId = ExtensionRelationId,
-		    .objectId = pgduckdb::ExtensionOid(),
+		ObjectAddress server_address = {
+		    .classId = ForeignServerRelationId,
+		    .objectId = GetMotherduckForeignServerOid(), // pgduckdb::ExtensionOid(),
 		    .objectSubId = 0,
 		};
-		recordDependencyOn(&schema_address, &extension_address, DEPENDENCY_NORMAL);
+		recordDependencyOn(&schema_address, &server_address, DEPENDENCY_NORMAL);
 	}
 
 	/* Success, so we commit the subtransaction */

test/pycheck/motherduck_test.py

@@ -59,6 +59,22 @@ def test_md_create_table(md_cur: Cursor, ddb):
     ):
         md_cur.sql("CREATE TABLE t4(a int) USING heap")
 
+def test_md_table_dropped_when_disabled(md_cur: Cursor, ddb):
+    ddb.sql("CREATE TABLE t1(a int, b varchar)")
+    ddb.sql("INSERT INTO t1 VALUES (1, 'abc')")
+    md_cur.wait_until_table_exists("t1")
+
+    assert md_cur.sql("SELECT * FROM t1") == (1, "abc")
+
+    # Disable MD, should CASCADE drop the table
+    md_cur.sql("DROP SERVER motherduck CASCADE;")
+
+    with pytest.raises(
+        psycopg.errors.UndefinedTable,
+        match=r'relation "t1" does not exist',
+    ):
+        md_cur.sql("SELECT * FROM t1")
+
 
 def test_md_default_db_escape(pg: Postgres, ddb, default_db_name, md_test_user):
     # Make sure MD is not enabled