Re: Synchronous replication
От | Yeb Havinga |
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Тема | Re: Synchronous replication |
Дата | |
Msg-id | 4C4E9BDA.5070202@gmail.com обсуждение исходный текст |
Ответ на | Re: Synchronous replication (Fujii Masao <masao.fujii@gmail.com>) |
Ответы |
Re: Synchronous replication
(Fujii Masao <masao.fujii@gmail.com>)
|
Список | pgsql-hackers |
Fujii Masao wrote: > On Mon, Jul 26, 2010 at 8:25 PM, Robert Haas <robertmhaas@gmail.com> wrote: > >> On Mon, Jul 26, 2010 at 6:48 AM, Marko Tiikkaja >> <marko.tiikkaja@cs.helsinki.fi> wrote: >> >>> On 7/26/10 1:44 PM +0300, Fujii Masao wrote: >>> >>>> On Mon, Jul 26, 2010 at 6:36 PM, Yeb Havinga<yebhavinga@gmail.com> wrote: >>>> >>>>> I wasn't entirely clear. My suggestion was to have only >>>>> >>>>> acknowledge_commit = {no|recv|fsync|replay} >>>>> >>>>> instead of >>>>> >>>>> replication_mode = {async|recv|fsync|replay} >>>>> >>>> Okay, I'll change the patch accordingly. >>>> >>> For what it's worth, I think replication_mode is a lot clearer. >>> Acknowledge_commit sounds like it would do something similar to >>> asynchronous_commit. >>> >> I agree. >> > > As the result of the vote, I'll leave the parameter "replication_mode" > as it is. > I'd like to bring forward another suggestion (please tell me when it is becoming spam). My feeling about replication_mode as is, is that is says in the same parameter something about async or sync, as well as, if sync, which method of feedback to the master. OTOH having two parameters would need documentation that the feedback method may only be set if the replication_mode was sync, as well as checks. So it is actually good to have it all in one parameter But somehow the shoe pinches, because async feels different from the other three parameters. There is a way to move async out of the enumeration: synchronous_replication_mode = off | recv | fsync | replay This also looks a bit like the "synchronous_replication = N # similar in name to synchronous_commit" Simon Riggs proposed in http://archives.postgresql.org/pgsql-hackers/2010-05/msg01418.php regards, Yeb Havinga PS: Please bear with me, I thought a bit about a way to make clear what deduction users must make when figuring out if the replication mode is synchronous. That question might be important when counting 'which servers are the synchronous standbys' to debug quorum settings. replication_mode from the assumption !async -> sync and !async -> recv|fsync|replay to infer recv|fsync|replay -> synchronous_replication. synchronous_replication_mode from the assumption !off -> on and !off -> recv|fsync|replay to infer recv|fsync|replay -> synchronous_replication. I think the last one is easier made by humans, since everybody will make the !off-> on assumption, but not the !async -> sync without having that verified in the documentation.
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