Thread: Built-in log rotation

Greetings!  I've been doing some research into log rotation software and
ran into this, while looking through the postgres site:

"There is a built-in log rotation program, which you can use by setting
the configuration parameter redirect_stderr to true in postgresql.conf."
http://www.postgresql.org/docs/8.1/interactive/logfile-maintenance.html

My question is, how does it rotate logs?  Does it perform a
copy/truncate of the logfile?  I know in older versions of postgres, if
you tried to move the log file, and create one with the same name, the
server wouldn't actually write to it without a restart...at least in
linux it wouldn't.  Do many of you use this mechanism?  If not, what
have you found to be a reliable solution?

Thanks in advance for the info!

- Kris

Kris Kiger wrote:
> Greetings!  I've been doing some research into log rotation software and
> ran into this, while looking through the postgres site:
>
> "There is a built-in log rotation program, which you can use by setting
> the configuration parameter redirect_stderr to true in postgresql.conf."
> http://www.postgresql.org/docs/8.1/interactive/logfile-maintenance.html
>
> My question is, how does it rotate logs?

It closes the old file and opens a new one -- new name, new file
descriptor, so the problem you mention below doesn't exist anymore.

> Does it perform a
> copy/truncate of the logfile?  I know in older versions of postgres, if
> you tried to move the log file, and create one with the same name, the
> server wouldn't actually write to it without a restart...at least in
> linux it wouldn't.

This code is "new" (only two years old).

--
Alvaro Herrera                                http://www.CommandPrompt.com/
PostgreSQL Replication, Consulting, Custom Development, 24x7 support