code: func PgOpclassByOid(db XODB, oid pgtypes.Oid) (*PgOpclass, error) {
  	var err error
  
  	// sql query
  	const sqlstr = `SELECT ` +
  		`tableoid, cmax, xmax, cmin, xmin, oid, ctid, opcmethod, opcname, opcnamespace, opcowner, opcfamily, opcintype, opcdefault, opckeytype ` +
  		`FROM pg_catalog.pg_opclass ` +
  		`WHERE oid = $1`
  
  	// run query
  	XOLog(sqlstr, oid)
  	po := PgOpclass{}
  
  	err = db.QueryRow(sqlstr, oid).Scan(&po.Tableoid, &po.Cmax, &po.Xmax, &po.Cmin, &po.Xmin, &po.Oid, &po.Ctid, &po.Opcmethod, &po.Opcname, &po.Opcnamespace, &po.Opcowner, &po.Opcfamily, &po.Opcintype, &po.Opcdefault, &po.Opckeytype)
  	if err != nil {
  		return nil, err
  	}
  
  	return &po, nil
  }
docs: // PgOpclassByOid retrieves a row from 'pg_catalog.pg_opclass' as a PgOpclass.
  //
  // Generated from index 'pg_opclass_oid_index'.