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

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

$udf = YQL::@@
(lambda '(key stream) 
    (PartitionByKey stream
        (lambda '(item) (Way item))
        (Void)
        (Void)
        (lambda '(listOfPairs)
            (FlatMap listOfPairs
                (lambda '(pair) (Just (AsStruct '('key key) '('src (Nth pair '0)) '('cnt (Length (ForwardList (Nth pair '1)))))))
            )
        )
    )
)
@@;

$src = (select * from plato.Input where key > "200");

$r = (REDUCE Input, (select * from Input where key > "100"), $src ON key USING $udf(TableRow()));

SELECT key, src, cnt FROM $r ORDER BY key, src, cnt;