CreateQuery t20 (children 3)
 Identifier t20
 Columns definition (children 1)
  ExpressionList (children 2)
   ColumnDeclaration a (children 1)
    DataType UInt32
   ColumnDeclaration b (children 1)
    DataType UInt32
 Storage definition (children 4)
  Function MergeTree
  Identifier a
  Identifier a
  Set