code: func PgPolicyByOid(db XODB, oid pgtypes.Oid) (*PgPolicy, error) {
  	var err error
  
  	// sql query
  	const sqlstr = `SELECT ` +
  		`tableoid, cmax, xmax, cmin, xmin, oid, ctid, polname, polrelid, polcmd, polroles, polqual, polwithcheck ` +
  		`FROM pg_catalog.pg_policy ` +
  		`WHERE oid = $1`
  
  	// run query
  	XOLog(sqlstr, oid)
  	pp := PgPolicy{}
  
  	err = db.QueryRow(sqlstr, oid).Scan(&pp.Tableoid, &pp.Cmax, &pp.Xmax, &pp.Cmin, &pp.Xmin, &pp.Oid, &pp.Ctid, &pp.Polname, &pp.Polrelid, &pp.Polcmd, &pp.Polroles, &pp.Polqual, &pp.Polwithcheck)
  	if err != nil {
  		return nil, err
  	}
  
  	return &pp, nil
  }
docs: // PgPolicyByOid retrieves a row from 'pg_catalog.pg_policy' as a PgPolicy.
  //
  // Generated from index 'pg_policy_oid_index'.