Re: Hot Backup

On 8 Oct 2002 at 14:17, Erwan DUROSELLE wrote:

>
> MvO> http://www.postgresql.org/idocs/index.php?wal.html
> - The URL you refer to is the ch11 I was refering to. It seems that this chapter is not as easily understandable as
itshould... 
> It says that with WAL, "pg is able to garantee consistency in the case of a crash".
> OK, but I think  is about /consistency/.
> For what I understand, it just says that in the case of a core dump of a server process (improbable) or a power cut
(probable)or an unwanted kill -9 (may happen), Pg will not have any corrupted table or index.  
>
> Cool, but not enough.
>
> As Timur pointed out, I was refering to a disk crash or total loss of a server.
> In this case, you loose up to 1 day of data.
> > There is a need in "incremental" backup, which backs up only those
> > transactions which has been fulfilled after last "full dump" or last
> > "incremental dump".  These backups should be done quite painlessly -
> > just copy some part of WAL, and should be small enough (compared to
> > full dump), so they can be done each hour or even more frequently..
> >
> > I hope sometime PostgreSQL will support that. :-)

Well, there are replication solutions which rsyncs WAL files after they are
rotated so two database instances are upto sync with each other at a difference
of one WAL file. If you are interested I can post the pdf.

I guess that takes care of scenario you plan to avoid..

Bye
 Shridhar

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