On Thu, Sep 4, 2008 at 8:58 PM, Duan Ligong <duanlg@nec-as.nec.com.cn> wrote:
> Thanks for your reply.
>
> Greg wrote:
>> On Tue, 2 Sep 2008, Duan Ligong wrote:
>> > - Does Vacuum delete the old clog files?
>>
>> Yes, if those transactions are all done. One possibility here is that
>> you've got some really long-running transaction floating around that is
>> keeping normal clog cleanup from happening. Take a look at the output
>> from "select * from pg_stat_activity" and see if there are any really old
>> transactions floating around.
>
> Well, we could not wait so long and just moved the old clog files.
> The postgresql system is running well.
> But now the size of pg_clog has exceeded 50MB and there
> are 457 clog files.
That is absolutely not the thing to do. Put them back, and do a
dump-restore on the database if you need to save a few hundred megs on
the drive. Deleting files from underneath postgresql is a great way
to break your database in new and interesting ways which are often
fatal to your data.