Re: When IMMUTABLE is not.
От | chap@anastigmatix.net |
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Тема | Re: When IMMUTABLE is not. |
Дата | |
Msg-id | 69234e25e34e68425f49630f79ef9991@anastigmatix.net обсуждение исходный текст |
Ответ на | Re: When IMMUTABLE is not. (Tom Lane <tgl@sss.pgh.pa.us>) |
Ответы |
Re: When IMMUTABLE is not.
Re: When IMMUTABLE is not. Re: When IMMUTABLE is not. |
Список | pgsql-hackers |
On 2023-06-15 09:21, Tom Lane wrote: > Yura Sokolov <y.sokolov@postgrespro.ru> writes: >> not enough to be sure function doesn't manipulate data. > > Of course not. It is the user's responsibility to mark functions > properly. And also, isn't it the case that IMMUTABLE should mark a function, not merely that "doesn't manipulate data", but whose return value doesn't depend in any way on data (outside its own arguments)? The practice among PLs of choosing an SPI readonly flag based on the IMMUTABLE/STABLE/VOLATILE declaration seems to be a sort of peculiar heuristic, not something inherent in what that declaration means to the optimizer. (And also influences what snapshot the function is looking at, and therefore what it can see, which has also struck me more as a tacked-on effect than something inherent in the declaration's meaning.) Regards, -Chap
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