code: func PgXactCommitTimestamp(db XODB, v0 pgtypes.Xid) (time.Time, error) {
  	var err error
  
  	// sql query
  	const sqlstr = `SELECT pg_catalog.pg_xact_commit_timestamp($1)`
  
  	// run query
  	var ret time.Time
  	XOLog(sqlstr, v0)
  	err = db.QueryRow(sqlstr, v0).Scan(&ret)
  	if err != nil {
  		return time.Time{}, err
  	}
  
  	return ret, nil
  }
docs: // PgXactCommitTimestamp calls the stored procedure 'pg_catalog.pg_xact_commit_timestamp(xid) timestamp with time zone' on db.