CreateQuery t1 (children 3)
 Identifier t1
 Columns definition (children 1)
  ExpressionList (children 3)
   ColumnDeclaration key (children 1)
    DataType UInt32
   ColumnDeclaration a (children 1)
    DataType UInt32
   ColumnDeclaration attr (children 1)
    DataType String
 Storage definition (children 2)
  Function MergeTree
  Identifier key
