Method CreateCheckpointTable

go/logic/applier.go:619–657

Create the checkpoint table to store the chunk copy and applier state. There are two sets of columns with the same types as the shared unique key, one for IterationMinValues and one for IterationMaxValues.

()

// There are two sets of columns with the same types as the shared unique key,
// one for IterationMinValues and one for IterationMaxValues.
func (apl *Applier) CreateCheckpointTable() error {
	if err := apl.DropCheckpointTable(); err != nil {
		return err
	}
	colDefs := []string{
		"`gh_ost_chk_id` bigint auto_increment primary key",
		"`gh_ost_chk_timestamp` bigint",
		"`gh_ost_chk_coords` text charset ascii",
		"`gh_ost_chk_iteration` bigint",
		"`gh_ost_rows_copied` bigint",
		"`gh_ost_dml_applied` bigint",
		"`gh_ost_is_cutover` tinyint(1) DEFAULT '0'",
	}
	for _, col := range apl.migrationContext.UniqueKey.Columns.Columns() {
		if col.MySQLType == "" {
			return fmt.Errorf("column %s has no type information. applyColumnTypes must be called", sql.EscapeName(col.Name))
		}
		minColName := sql.TruncateColumnName(col.Name, sql.MaxColumnNameLength-4) + "_min"
		colDef := fmt.Sprintf("%s %s", sql.EscapeName(minColName), col.MySQLType)
		colDefs = append(colDefs, colDef)
	}

	for _, col := range apl.migrationContext.UniqueKey.Columns.Columns() {
		maxColName := sql.TruncateColumnName(col.Name, sql.MaxColumnNameLength-4) + "_max"
		colDef := fmt.Sprintf("%s %s", sql.EscapeName(maxColName), col.MySQLType)
		colDefs = append(colDefs, colDef)
	}

	query := fmt.Sprintf("create /* gh-ost */ table %s.%s (\n %s\n)",
		sql.EscapeName(apl.migrationContext.DatabaseName),
		sql.EscapeName(apl.migrationContext.GetCheckpointTableName()),
		strings.Join(colDefs, ",\n "),
	)
	apl.migrationContext.Log.Infof("Created checkpoint table")
	if _, err := sqlutils.ExecNoPrepare(apl.db, query); err != nil {
		return err
	}
	return nil
}

// dropTable drops a given table on the applied host
func (apl *Applier) dropTable(tableName string) error {