CreateQuery t1 (children 3)
 Identifier t1
 Storage definition (children 2)
  Function MergeTree (children 1)
   ExpressionList
  Function tuple (children 1)
   ExpressionList
 SelectWithUnionQuery (children 1)
  ExpressionList (children 1)
   SelectQuery (children 1)
    ExpressionList (children 2)
     Literal UInt64_1 (alias user_id)
     Literal UInt64_2 (alias level)
