Re: [GENERAL] Custom shuffle function stopped working in 9.6
От | Pavel Stehule |
---|---|
Тема | Re: [GENERAL] Custom shuffle function stopped working in 9.6 |
Дата | |
Msg-id | CAFj8pRAbcVUrkQM_5zsOLj=szKtQUuG3J0t=nAEsNuWhfxTOVQ@mail.gmail.com обсуждение исходный текст |
Ответ на | [GENERAL] Custom shuffle function stopped working in 9.6 (Alexander Farber <alexander.farber@gmail.com>) |
Ответы |
Re: [GENERAL] Custom shuffle function stopped working in 9.6
|
Список | pgsql-general |
Hi
2017-02-11 17:37 GMT+01:00 Alexander Farber <alexander.farber@gmail.com>:
Good evening,after switching to 9.6.2 from 9.5.3 the following custom function has stopped working:CREATE OR REPLACE FUNCTION words_shuffle(in_array varchar[])RETURNS varchar[] AS$func$SELECT array_agg(letters.x) FROM(SELECT UNNEST(in_array) x ORDER BY RANDOM()) letters;$func$ LANGUAGE sql STABLE;In 9.5.3 it was shuffling characters:words=> select words_shuffle(ARRAY['a','b','c','d','e','f']); words_shuffle---------------{c,d,b,a,e,f}(1 row)But in 9.6.2 it has stopped doing so:words=> select words_shuffle(ARRAY['a','b','c','d','e','f']); words_shuffle---------------{a,b,c,d,e,f}(1 row)Any suggestions for a better shuffling function please?
CREATE OR REPLACE FUNCTION words_shuffle(in_array varchar[])
RETURNS varchar[] AS
$func$
SELECT array_agg(letters.x) FROM
(SELECT x FROM UNNEST(in_array) x ORDER BY RANDOM()) letters;
$func$ LANGUAGE sql STABLE;
there was some optimisations for faster expression evaluation - probably this is one effect of this optimisation.
generally SRF function should not be used in target list - now when we have LATERAL join, it is not necessary
Regards
Pavel
RegardsAlex
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