CreateQuery t2 (children 3)
 Identifier t2
 Columns definition (children 1)
  ExpressionList (children 1)
   ColumnDeclaration y (children 1)
    DataType Nullable (children 1)
     ExpressionList (children 1)
      DataType Int
 Storage definition (children 3)
  Function MergeTree
  Identifier y
  Set
