CreateQuery test_index (children 3)
 Identifier test_index
 Columns definition (children 1)
  ExpressionList (children 1)
   ColumnDeclaration date (children 1)
    DataType Date
 Storage definition (children 3)
  Function MergeTree
  Function toYYYYMM (children 1)
   ExpressionList (children 1)
    Identifier date
  Identifier date
