Function TestLazyExecuteProjection

pkg/server/tests/cursor/cursor_test.go:312–372

(t *testing.T)

}

func TestLazyExecuteProjection(t *testing.T) {
	ts := servertestkit.CreateTidbTestSuite(t)

	mysqldriver := &mysqlcursor.MySQLDriver{}
	rawConn, err := mysqldriver.Open(ts.GetDSNWithCursor(10))
	require.NoError(t, err)
	conn := rawConn.(mysqlcursor.Connection)
	defer conn.Close()

	_, err = conn.ExecContext(context.Background(), "drop table if exists t1", nil)
	require.NoError(t, err)
	_, err = conn.ExecContext(context.Background(), "create table t1(id int primary key, v int)", nil)
	require.NoError(t, err)
	rowCount := 1000
	for i := 0; i < rowCount; i++ {
		_, err = conn.ExecContext(context.Background(), fmt.Sprintf("insert into t1 values(%d, %d)", i, i), nil)
		require.NoError(t, err)
	}

	_, err = conn.ExecContext(context.Background(), "set tidb_enable_lazy_cursor_fetch = 'ON'", nil)
	require.NoError(t, err)

	require.NoError(t, failpoint.Enable("github.com/pingcap/tidb/pkg/server/avoidEagerCursorFetch", "return"))
	defer func() {
		require.NoError(t, failpoint.Disable("github.com/pingcap/tidb/pkg/server/avoidEagerCursorFetch"))
	}()

	// Normal execute. Simple table reader.
	execTimes := 0
outerLoop:
	for execTimes < 50 {
		execTimes++
		rawStmt, err := conn.Prepare("select id + v from t1 order by id")
		require.NoError(t, err)
		stmt := rawStmt.(mysqlcursor.Statement)

		// This query will return `rowCount` rows and use cursor fetch.
		rows, err := stmt.QueryContext(context.Background(), nil)
		require.NoError(t, err)

		dest := make([]driver.Value, 1)
		fetchRowCount := int64(0)

		for {
			// it'll send `FETCH` commands for every 10 rows.
			err := rows.Next(dest)
			if err != nil {
				switch err {
				case io.EOF:
					require.Equal(t, int64(rowCount), fetchRowCount)
					rows.Close()
					break outerLoop
				default:
					require.NoError(t, err)
				}
			}
			require.Equal(t, fetchRowCount*2, dest[0])
			fetchRowCount++