CreateQuery aggregate_functions_null_for_empty (children 3)
 Identifier aggregate_functions_null_for_empty
 Columns definition (children 2)
  ExpressionList (children 2)
   ColumnDeclaration x (children 1)
    DataType UInt32
   ColumnDeclaration y (children 1)
    DataType UInt64
  ExpressionList (children 1)
   Projection (children 1)
    ProjectionSelectQuery (children 1)
     ExpressionList (children 1)
      Function sum (children 1)
       ExpressionList (children 1)
        Identifier y
 Storage definition (children 2)
  Function MergeTree
  Function tuple (children 1)
   ExpressionList
