SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 5)
   ExpressionList (children 5)
    Identifier a._shard_num
    Identifier a.key
    Identifier b.host_name
    Function in (children 1)
     ExpressionList (children 2)
      Identifier b.host_address
      Literal Tuple_(\'::1\', \'127.0.0.1\')
    Identifier b.port
   TablesInSelectQuery (children 2)
    TablesInSelectQueryElement (children 1)
     TableExpression (children 1)
      TableIdentifier dist_1 (alias a)
    TablesInSelectQueryElement (children 2)
     TableExpression (children 1)
      TableIdentifier system.clusters (alias b)
     TableJoin (children 1)
      Function equals (children 1)
       ExpressionList (children 2)
        Identifier a._shard_num
        Identifier b.shard_num
   Function equals (children 1)
    ExpressionList (children 2)
     Identifier b.cluster
     Literal \'test_cluster_two_shards_localhost\'
   ExpressionList (children 1)
    OrderByElement (children 1)
     Identifier key
   Set