Explain EXPLAIN PIPELINE (children 1)
 SelectWithUnionQuery (children 1)
  ExpressionList (children 1)
   SelectQuery (children 3)
    ExpressionList (children 1)
     Identifier a
    TablesInSelectQuery (children 1)
     TablesInSelectQueryElement (children 1)
      TableExpression (children 1)
       Function remote (children 1)
        ExpressionList (children 3)
         Identifier test_cluster_two_shards
         Function currentDatabase (children 1)
          ExpressionList
         Identifier dist_t
    ExpressionList (children 1)
     Identifier a
