Function TestStmtCacheInvalidationConn

conn_test.go:1218–1278

(t *testing.T)

}

func TestStmtCacheInvalidationConn(t *testing.T) {
	ctx := context.Background()

	conn := mustConnectString(t, os.Getenv("PGX_TEST_DATABASE"))
	defer closeConn(t, conn)

	// create a table and fill it with some data
	_, err := conn.Exec(ctx, `
        DROP TABLE IF EXISTS drop_cols;
        CREATE TABLE drop_cols (
            id SERIAL PRIMARY KEY NOT NULL,
            f1 int NOT NULL,
            f2 int NOT NULL
        );
    `)
	require.NoError(t, err)
	_, err = conn.Exec(ctx, "INSERT INTO drop_cols (f1, f2) VALUES (1, 2)")
	require.NoError(t, err)

	getSQL := "SELECT * FROM drop_cols WHERE id = $1"

	// This query will populate the statement cache. We don't care about the result.
	rows, err := conn.Query(ctx, getSQL, 1)
	require.NoError(t, err)
	rows.Close()
	require.NoError(t, rows.Err())

	// Now, change the schema of the table out from under the statement, making it invalid.
	_, err = conn.Exec(ctx, "ALTER TABLE drop_cols DROP COLUMN f1")
	require.NoError(t, err)

	// We must get an error the first time we try to re-execute a bad statement.
	// It is up to the application to determine if it wants to try again. We punt to
	// the application because there is no clear recovery path in the case of failed transactions
	// or batch operations and because automatic retry is tricky and we don't want to get
	// it wrong at such an important layer of the stack.
	rows, err = conn.Query(ctx, getSQL, 1)
	require.NoError(t, err)
	rows.Next()
	nextErr := rows.Err()
	rows.Close()
	for _, err := range []error{nextErr, rows.Err()} {
		if err == nil {
			t.Fatal(`expected "cached plan must not change result type": no error`)
		}
		if !strings.Contains(err.Error(), "cached plan must not change result type") {
			t.Fatalf(`expected "cached plan must not change result type", got: "%s"`, err.Error())
		}
	}

	// On retry, the statement should have been flushed from the cache.
	rows, err = conn.Query(ctx, getSQL, 1)
	require.NoError(t, err)
	rows.Next()
	err = rows.Err()
	require.NoError(t, err)
	rows.Close()
	require.NoError(t, rows.Err())