CreateQuery test_index (children 3)
 Identifier test_index
 Columns definition (children 2)
  ExpressionList (children 2)
   ColumnDeclaration key_string (children 1)
    DataType String
   ColumnDeclaration key_uint32 (children 1)
    Function toUInt32 (children 1)
     ExpressionList (children 1)
      Identifier key_string
  ExpressionList (children 1)
   Index (children 2)
    Function toUInt32 (children 1)
     ExpressionList (children 1)
      Identifier key_string
    Function set (children 1)
     ExpressionList (children 1)
      Literal UInt64_0
 Storage definition (children 5)
  Function MergeTree
  Function tuple (children 1)
   ExpressionList
  Function tuple (children 1)
   ExpressionList
  Identifier key_string
  Set