Include memory.main in Flight SQL worker session search_path

When a Flight SQL worker session initializes, initSearchPath() sets
search_path to '<username>,main'. With DuckLake as the default catalog,
'main' resolves to 'ducklake.main', excluding memory.main where
pg_catalog macros (pg_get_userbyid, format_type, etc.) are created.
This breaks psql backslash commands (\dt, \d, etc.) on K8s shared
warm workers.

The non-K8s control plane path doesn't hit this because it leaves
search_path unset (empty/default), which lets DuckDB resolve functions
across all catalogs.

Fix by appending memory.main to the search_path in initSearchPath().
When DuckLake isn't active, memory.main is redundant but harmless.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: fuziontech

duckdbservice/service.go

@@ -624,13 +624,18 @@ func dropTemporary(ctx context.Context, conn *sql.Conn, query, dropFmt string) {
 
 // initSearchPath sets the DuckDB search_path for a session connection.
 // It tries to include the user's schema first; if that schema doesn't exist,
-// it falls back to just 'main' (DuckDB's default schema).
+// it falls back to just 'main'.
+//
+// memory.main is always included so that pg_catalog macros (pg_get_userbyid,
+// format_type, etc.) remain resolvable when the default catalog is ducklake.
+// Without it, DuckDB restricts function resolution to the ducklake catalog
+// and psql commands like \dt fail.
 func initSearchPath(conn *sql.Conn, username string) {
-	if _, err := conn.ExecContext(context.Background(), fmt.Sprintf("SET search_path = '%s,main'", username)); err != nil {
+	if _, err := conn.ExecContext(context.Background(), fmt.Sprintf("SET search_path = '%s,main,memory.main'", username)); err != nil {
 		slog.Debug("User schema not found, using default search_path.", "user", username)
 		// Clear the aborted transaction state before retrying.
 		_, _ = conn.ExecContext(context.Background(), "ROLLBACK")
-		if _, err := conn.ExecContext(context.Background(), "SET search_path = 'main'"); err != nil {
+		if _, err := conn.ExecContext(context.Background(), "SET search_path = 'main,memory.main'"); err != nil {
 			slog.Warn("Failed to set search_path for session.", "user", username, "error", err)
 		}
 	}

duckdbservice/service_test.go

@@ -29,8 +29,8 @@ func TestInitSearchPath(t *testing.T) {
 		if err := conn.QueryRowContext(context.Background(), "SELECT current_setting('search_path')").Scan(&searchPath); err != nil {
 			t.Fatalf("failed to query search_path: %v", err)
 		}
-		if searchPath != "main" {
-			t.Errorf("expected search_path 'main', got %q", searchPath)
+		if searchPath != "main,memory.main" {
+			t.Errorf("expected search_path 'main,memory.main', got %q", searchPath)
 		}
 	})
 
@@ -52,8 +52,8 @@ func TestInitSearchPath(t *testing.T) {
 		if err := conn.QueryRowContext(context.Background(), "SELECT current_setting('search_path')").Scan(&searchPath); err != nil {
 			t.Fatalf("failed to query search_path: %v", err)
 		}
-		if searchPath != "myuser,main" {
-			t.Errorf("expected search_path 'myuser,main', got %q", searchPath)
+		if searchPath != "myuser,main,memory.main" {
+			t.Errorf("expected search_path 'myuser,main,memory.main', got %q", searchPath)
 		}
 	})
 }

server/server.go

@@ -1265,12 +1265,6 @@ func setDuckLakeDefault(db *sql.DB) error {
 	if _, err := db.Exec("USE ducklake"); err != nil {
 		return fmt.Errorf("failed to set DuckLake as default catalog: %w", err)
 	}
-	// Include memory.main in the search path so pg_catalog macros (pg_get_userbyid,
-	// format_type, etc.) created in memory.main are resolvable. Without this, psql
-	// commands like \dt fail because DuckDB doesn't resolve functions across catalogs.
-	if _, err := db.Exec("SET search_path = 'ducklake.main,memory.main'"); err != nil {
-		return fmt.Errorf("failed to set search_path for DuckLake: %w", err)
-	}
 	slog.Info("Set DuckLake as default catalog.")
 	return nil
 }