Function cursorBackwardFlow

tests/integration/cursor_test.go:150–164

cursorBackwardFlow covers the forward-only restriction: backward fetch fails with a clean error. NO SCROLL pins real PostgreSQL to the same forward-only behavior Duckgres always has (without it, PostgreSQL can satisfy backward fetches from materialized plans like sorts).

(t *testing.T, db *sql.DB)

// forward-only behavior Duckgres always has (without it, PostgreSQL can
// satisfy backward fetches from materialized plans like sorts).
func cursorBackwardFlow(t *testing.T, db *sql.DB) {
	tx := beginCursorTx(t, db)

	mustExecTx(t, tx, "DECLARE cur_backward NO SCROLL CURSOR FOR SELECT id, name FROM users ORDER BY id")
	assertCursorRows(t, "FETCH 2", fetchCursorRows(t, tx, "FETCH 2 FROM cur_backward"), cursorUsers(1, 2))

	rows, err := tx.Query("FETCH BACKWARD 1 FROM cur_backward")
	if err == nil {
		_ = rows.Close()
		t.Fatal("FETCH BACKWARD succeeded, want forward-only error")
	}
	if !strings.Contains(err.Error(), "cursor can only scan forward") {
		t.Errorf("FETCH BACKWARD: error = %q, want forward-only error", err)
	}
}

// cursorMissingFlow covers FETCH/CLOSE on a cursor that was never declared.
// Each statement gets its own transaction because the error aborts the