strace –p <pid> -c
Then do a “CTRL-C” after a minute to get the stats of system calls.
- Luke
On 4/20/06 2:13 PM, "Brendan Duddridge" <brendan@xxxxxxxxxxxxxx> wrote:
Hi Tom,
Do you mean do a kill -QUIT on the postgres process in order to
generate a stack trace?
Will that affect the currently running process in any bad way? And
where would the output go? stdout?
Thanks,
____________________________________________________________________
Brendan Duddridge | CTO | 403-277-5591 x24 | brendan@xxxxxxxxxxxxxx
ClickSpace Interactive Inc.
Suite L100, 239 - 10th Ave. SE
Calgary, AB T2G 0V9
http://www.clickspace.com
On Apr 20, 2006, at 2:17 PM, Tom Lane wrote:
> Brendan Duddridge <brendan@xxxxxxxxxxxxxx> writes:
>> We had a database issue today that caused us to have to restore to
>> our most recent backup. We are using PITR so we have 3120 WAL files
>> that need to be applied to the database.
>> After 45 minutes, it has restored only 230 WAL files. At this rate,
>> it's going to take about 10 hours to restore our database.
>> Most of the time, the server is not using very much CPU time or I/O
>> time. So I'm wondering what can be done to speed up the process?
>
> That seems a bit odd --- should be eating one or the other, one would
> think. Try strace'ing the recovery process to see what it's doing.
>
>> If there were something we could do to speed up the process, would it
>> be possible to kill the postgres process, tweak some parameter
>> somewhere and then start it up again? Or would we have to restore our
>> base backup again and start over?
>
> You could start it up again, but it'd want to read through all the WAL
> it's already looked at, so I'd not recommend this until/unless you're
> pretty sure you've fixed the performance issue. Right at the moment,
> I think this is a golden opportunity to study the performance of WAL
> recovery --- it's not something we've tried to optimize particularly.
>
> regards, tom lane
>
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