Re: Is full_page_writes=off safe in conjunction with

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От Hannu Krosing
Тема Re: Is full_page_writes=off safe in conjunction with
Дата
Msg-id 1145049565.7917.1.camel@localhost.localdomain
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Ответ на Is full_page_writes=off safe in conjunction with PITR?  (Tom Lane <tgl@sss.pgh.pa.us>)
Ответы Re: Is full_page_writes=off safe in conjunction with PITR?  (Tom Lane <tgl@sss.pgh.pa.us>)
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Ühel kenal päeval, R, 2006-04-14 kell 16:40, kirjutas Tom Lane:

> I think we had originally argued that there was no problem anyway
> because the kernel should cause the page write to appear atomic to other
> processes (since we issue it in a single write() command).  But that's
> only true if the backup-taker reads in units that are multiples of
> BLCKSZ.  If the backup-taker reads, say, 4K at a time then it's
> certainly possible that it gets a later version of the second half of a
> page than it got of the first half.  I don't know about you, but I sure
> don't feel comfortable making assumptions at that level about the
> behavior of tar or cpio.
> 
> I fear we still have to disable full_page_writes (force it ON) if
> XLogArchivingActive is on.  Comments?

Why not just tell the backup-taker to take backups using 8K pages ? 

---------------
Hannu




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