Re: archived WALL files question

On 04/19/2010 10:26 AM, Kevin Grittner wrote:
> Frederiko Costa<frederiko@gmail.com>  wrote:
>
>> I have seen new 16 MB segments files created in pg_xlog directory
>> as time goes on. Honestly, I did not understand why it got
>> created, because I was running it on a VM and there was no
>> activity. I got several new segments.
>>
>> If I run the command you asked, this is the output. Neither
>> segment is copied, nor a new segment file gets created:
>>
>>    select pg_switch_xlog();
>>    pg_switch_xlog
>> ----------------
>>    0/81000088
>> (1 row)
>>
>
> What version of PostgreSQL is this?
>
8.4.3
>
> What do you see if you run?:
>
> show archive_command;
>
cp -p %p /mnt/data/%f
> show archive_mode;
>
on
> show archive_timeout;
>
1min
I have just enabled that. Now, log files are being copied directly to
the /mnt/data dir. However, the same segments are not in the pg_xlog
dir. Is this a default behaviour?

Must I set archive_timeout? I don't think I want that, because,
specially for the next few months, where the activity would be very
limited and I would get several zero written segments just because
timeout has been reached. Is this approach recommended anyway? Or is it
better to use this approach even having limited approach?

> Check your log file from the time you ran pg_switch_xlog to look for
> any messages which might give a clue to what's happening.
>
>
The log files did not write anything about pg_switch_xlog.
> -Kevin
>