CreateQuery alter_index_test (children 3)
 Identifier alter_index_test
 Columns definition (children 2)
  ExpressionList (children 4)
   ColumnDeclaration a (children 1)
    DataType UInt32
   ColumnDeclaration b (children 1)
    DataType Date
   ColumnDeclaration c (children 1)
    DataType UInt32
   ColumnDeclaration d (children 1)
    DataType UInt32
  ExpressionList (children 1)
   Index (children 2)
    Identifier a
    Function set (children 1)
     ExpressionList (children 1)
      Literal UInt64_0
 Storage definition (children 2)
  Function MergeTree (children 1)
   ExpressionList
  Function tuple (children 1)
   ExpressionList
