Re: Check-out mutable functions in check constraints
От | Tomas Vondra |
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Тема | Re: Check-out mutable functions in check constraints |
Дата | |
Msg-id | 20190712111126.rz53ixlkiuknmtte@development обсуждение исходный текст |
Ответ на | Re: Check-out mutable functions in check constraints (Pavel Stehule <pavel.stehule@gmail.com>) |
Ответы |
Re: Check-out mutable functions in check constraints
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Список | pgsql-hackers |
On Fri, Jul 12, 2019 at 08:55:20AM +0200, Pavel Stehule wrote: >Hi > >pá 12. 7. 2019 v 8:45 odesílatel Kyotaro Horiguchi <horikyota.ntt@gmail.com> >napsal: > >> Hello. >> >> As mentioned in the following message: >> >> >> https://www.postgresql.org/message-id/20190712.150527.145133646.horikyota.ntt%40gmail.com >> >> Mutable function are allowed in check constraint expressions but >> it is not right. The attached is a proposed fix for it including >> regression test. >> >> Other "constraints vs xxxx" checks do not seem to be exercised >> but it would be another issue. >> > >I think so this feature (although is correct) can breaks almost all >applications - it is 20 year late. > I'm not sure it actually breaks such appliations. Let's assume you have a mutable function (i.e. it may change return value even with the same parameters) and you use it in a CHECK constraint. Then I'm pretty sure your application is already broken in various ways and you just don't know it (sometimes it subtle, sometimes less so). If you have a function that actually is immutable and it's just not marked accordingly, then that only requires a single DDL to fix that during upgrade. I don't think that's a massive issue. That being said, I don't know whether fixing this is worth the hassle. regards -- Tomas Vondra http://www.2ndQuadrant.com PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
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