Re: How to reduce WAL file Size

On 9 Oct 2009, at 8:48, Mitesh51 wrote:

> I am dealing with backup of databases. Now eventhough there are not
> many
> changes in the DB, it creates WAL file of 16 mb. Now because I am
> working on
> a application which takes full & inc backup of db after specific
> intervals..if for small changes it creates 16 mb files then storing
> them
> will eat up lot many space. As I am not having DB knowledge I am just
> assuming that it will create problems in terms of storage space.
> That is my
> concern.
>
> If you will explain this thing then it will help me in a good way :)

I thought as much, you can't just make a file-system backup of the WAL
files and expect you'll be able to recover your database from that.
Unless you take special measures your chances are minimal and the
method is inferior to the other possible approaches.

Backups are explained at length in the documentation, see http://www.postgresql.org/docs/8.4/static/backup.html

If your backup system can handle block- or byte-level incremental
backups it's probably easiest to just do a database dump to a fixed
file at regular intervals. The backup software will just backup the
differences since last backup after all.

Another common strategy is to use PITR (point in time recovery) for
your backups.

P.S. Please try to avoid top-posting.

> Alban Hertroys-3 wrote:

What's this? Did my name change suddenly? Or is yahoo-mail a bad mail
client?

>> On 8 Oct 2009, at 9:35, Mitesh51 wrote:
>>
>>> By setting postgres.conf params...log files are generated of 16 MB
>>> each. How
>>> can I reduce the size of this files? & can I force the log files to
>>> switch
>>> with any command as we do in mysql like flush log? where we force
>>> the new
>>> log creation ?
>>
>>
>> Why do you want to reduce the WAL file size? What problem are you
>> trying to solve?

Alban Hertroys

--
If you can't see the forest for the trees,
cut the trees and you'll see there is no forest.

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