Re: RE: [COMMITTERS] pgsql/src/backend/access/transam ( xact.c xlog.c)
От | Alfred Perlstein |
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Тема | Re: RE: [COMMITTERS] pgsql/src/backend/access/transam ( xact.c xlog.c) |
Дата | |
Msg-id | 20001116133630.N830@fw.wintelcom.net обсуждение исходный текст |
Ответ на | Re: RE: [COMMITTERS] pgsql/src/backend/access/transam ( xact.c xlog.c) (Tom Lane <tgl@sss.pgh.pa.us>) |
Ответы |
Re: RE: [COMMITTERS] pgsql/src/backend/access/transam ( xact.c xlog.c)
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Список | pgsql-hackers |
* Tom Lane <tgl@sss.pgh.pa.us> [001116 13:31] wrote: > Alfred Perlstein <bright@wintelcom.net> writes: > > It might make more sense to keep a private copy of the last time > > the file was modified per-backend by that particular backend and > > a timestamp of the last fsync shared globally so one can forgo the > > fsync if "it hasn't been dirtied by me since the last fsync" > > This would provide a rendevous point for the fsync call although > > cost more as one would need to periodically call gettimeofday to > > set the modified by me timestamp as well as the post-fsync shared > > timestamp. > > That's the hard way to do it. We just need to keep track of the > endpoint of the log as of the last fsync. You need to fsync (after > returning from sleep()) iff your commit record position > fsync > endpoint. No need to ask the kernel for time-of-day. Well that breaks when you move to a overwriting storage manager, however if you use oid instead that optimization would survive the change to a overwriting storage manager. ? -Alfred
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