Re: WIP checksums patch
От | Jeff Davis |
---|---|
Тема | Re: WIP checksums patch |
Дата | |
Msg-id | 1352503515.26644.24.camel@sussancws0025 обсуждение исходный текст |
Ответ на | Re: WIP checksums patch (Josh Berkus <josh@agliodbs.com>) |
Список | pgsql-hackers |
On Mon, 2012-10-01 at 10:22 -0700, Josh Berkus wrote: > > I think that's OK, because it's still protected by the WAL CRC, and > > there's no expectation that the checksum is correct in shared buffers, > > and the correct checksum should be set on the next checkpoint. Just an > > observation. > > We'd need to document that emphatically. Otherwise folks running on ZFS > and/or FusionIO with atomic writes (and, in the future, BTRFS) will > assume that they can turn "full_page_writes" off and checksums on, and > clearly that won't work with the current code. I think that's an > acceptable limitation, I just think we need to document it carefully, > and maybe throw a warning if people start up in that configuration. What situation are you concerned about here? I think that COW filesystems should still be safe with full_page_writes off, right? The checksum is calculated before every write, and the COW filesystems do atomic writes, so the checksums should always be fine. What am I missing? Regards,Jeff Davis
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