Method CountTableRows

go/logic/inspect.go:661–698

CountTableRows counts exact number of rows on the original table

(ctx context.Context)

// CountTableRows counts exact number of rows on the original table
func (isp *Inspector) CountTableRows(ctx context.Context) error {
	atomic.StoreInt64(&isp.migrationContext.CountingRowsFlag, 1)
	defer atomic.StoreInt64(&isp.migrationContext.CountingRowsFlag, 0)

	isp.migrationContext.Log.Infof("As instructed, I'm issuing a SELECT COUNT(*) on the table. This may take a while")

	conn, err := isp.db.Conn(ctx)
	if err != nil {
		return err
	}
	defer conn.Close()

	var connectionID string
	if err := conn.QueryRowContext(ctx, `SELECT /* gh-ost */ CONNECTION_ID()`).Scan(&connectionID); err != nil {
		return err
	}

	query := fmt.Sprintf(`select /* gh-ost */ count(*) as count_rows from %s.%s`, sql.EscapeName(isp.migrationContext.DatabaseName), sql.EscapeName(isp.migrationContext.OriginalTableName))
	var rowsEstimate int64
	if err := conn.QueryRowContext(ctx, query).Scan(&rowsEstimate); err != nil {
		if errors.Is(err, context.Canceled) || errors.Is(err, context.DeadlineExceeded) {
			isp.migrationContext.Log.Infof("exact row count cancelled (%s), likely because I'm about to cut over. I'm going to kill that query.", ctx.Err())
			return mysql.Kill(isp.db, connectionID)
		}
		return err
	}

	// row count query finished. nil out the cancel func, so the main migration thread
	// doesn't bother calling it after row copy is done.
	isp.migrationContext.SetCountTableRowsCancelFunc(nil)

	atomic.StoreInt64(&isp.migrationContext.RowsEstimate, rowsEstimate)
	isp.migrationContext.UsedRowsEstimateMethod = base.CountRowsEstimate

	isp.migrationContext.Log.Infof("Exact number of rows via COUNT: %d", rowsEstimate)

	return nil
}

// applyColumnTypes
func (isp *Inspector) applyColumnTypes(databaseName, tableName string, columnsLists ...*sql.ColumnList) error {