ydb/yt/yql/tests/sql/suites/produce/reduce_all_opt.sql

/* syntax version 1 */
/* postgres can not */
/* dqfile can not */
USE plato;

$udfScript = @@
import functools
def Len(stream):
    sums = [functools.reduce(lambda x,y: x + int(y.value), pair[1], 0) for pair in stream]
    return {"sumByAllVal":functools.reduce(lambda x,y: x + y, sums, 0)}
@@;

$udf = Python::Len(Callable<(Stream<Tuple<String,Stream<Struct<key:String,subkey:String,value:String>>>>)->Optional<Struct<sumByAllVal:Uint32>>>, $udfScript);

--INSERT INTO Output
REDUCE Input1 ON key USING ALL $udf(TableRow());