Re: plpgsql variable assignment not supporting distinct anymore
| От | Pavel Stehule |
|---|---|
| Тема | Re: plpgsql variable assignment not supporting distinct anymore |
| Дата | |
| Msg-id | CAFj8pRCicOt5+2A+qnYiZR+ryPDUV3Rof9nBZhy=K1jPkXNyYQ@mail.gmail.com обсуждение исходный текст |
| Ответы |
Re: plpgsql variable assignment not supporting distinct anymore
|
| Список | pgsql-hackers |
pá 22. 1. 2021 v 9:21 odesílatel <easteregg@verfriemelt.org> napsal:
hi,
no noticed after the assignment with union ( https://www.postgresql.org/message-id/flat/20210105201257.f0d76aff%40mail.verfriemelt.org ), that the assignment with distinct is broken aswell.
DO $$
DECLARE
_test bool;
BEGIN
_test := DISTINCT a FROM ( VALUES ( (true), ( true ) ) )t(a);
END $$;
i would argue, that thats a way more common usecase than the union, which was merely bad code.
What is the sense of this code?
This is strange with not well defined behavior (in dependency on data type the result can depend on collate).
More - because this breaks simple expression optimization (10x), then the code will be significantly slower, than you use IF or CASE.
Regards
Pavel
tested with version 14~~devel~20210111.0540-1~299.gitce6a71f.pgdg110+1 from the apt repo
with kind redards,
richard
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