Re: confusing checkpoint_flush_after / bgwriter_flush_after
От | Fabien COELHO |
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Тема | Re: confusing checkpoint_flush_after / bgwriter_flush_after |
Дата | |
Msg-id | alpine.DEB.2.20.1611251311350.18480@lancre обсуждение исходный текст |
Ответ на | confusing checkpoint_flush_after / bgwriter_flush_after (Tomas Vondra <tomas.vondra@2ndquadrant.com>) |
Ответы |
Re: confusing checkpoint_flush_after / bgwriter_flush_after
Re: confusing checkpoint_flush_after / bgwriter_flush_after |
Список | pgsql-hackers |
Hello Tomas, > #checkpoint_flush_after = 0 # 0 disables, > # default is 256kB on linux, 0 otherwise > I find this pretty confusing, because for all other GUCs in the file, the > commented-out value is the default one. In this case that would mean "0", > disabling the flushing. > > But in practice we use platform-dependent defaults - 256/512K on Linux, 0 > otherwise. There are other GUCs where the default is platform-specific, but > none of them suggests "disabled" is the default state. > > While the 9.6 cat is out of the bag, I think we can fix this quite easily - > use "-1" to specify the default value should be used, and use that in the > sample file. This won't break any user configuration. Although I understand the issue, I'm not sure about -1 as a special value to mean the default. > If that's considered not acceptable, perhaps we should at least improve the > comments, so make this clearer. Yep, what about not putting a value and inverting/adapting the comments, maybe something like: #checkpoint_flush_after = ... # default is 256kB on linux, 0 otherwise # where 0 disablesflushing -- Fabien.
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