Function writeCTEPrefix

backend/plugin/parser/tidb/backup.go:431–438

writeCTEPrefix writes the statement's WITH (CTE) clause before the backup SELECT, so a SELECT whose FROM references a CTE stays valid. omni does not attach UPDATE/DELETE CTEs to the statement node, so the prefix is recovered from the text before the statement Loc.

(buf *strings.Builder, node ast.Node, fullSQL string)

// attach UPDATE/DELETE CTEs to the statement node, so the prefix is recovered
// from the text before the statement Loc.
func writeCTEPrefix(buf *strings.Builder, node ast.Node, fullSQL string) error {
	cte := extractCTE(fullSQL, nodeStmtLoc(node))
	if cte == "" {
		return nil
	}
	_, err := fmt.Fprintf(buf, "%s ", cte)
	return err
}

// extractCTE returns the WITH-clause text preceding the statement, or "".
func extractCTE(fullSQL string, stmtLoc ast.Loc) string {