Re: Load Distributed Checkpoints, revised patch

On Jun 17, 2007, at 4:39 AM, Simon Riggs wrote:
>>> pg_start_backup() should be a normal checkpoint I think. No need for
>>> backup to be an intrusive process.
>>
>> Good point. A spread out checkpoint can take a long time to finish,
>> though. Is there risk for running into a timeout or something if it
>> takes say 10 minutes for a call to pg_start_backup to finish?
>
> That would be annoying, but the alternative is for backups to
> seriously
> effect performance, which would defeat the object of the HOT backup.
> It's not like its immediate right now, so we'd probably be moving from
> 2-3 mins to 10 mins in your example. Most people are expecting their
> backups to take a long time anyway, so thats OK.

We should document it, though; otherwise I can see a bunch of
confused users wondering why pg_start_backup takes so long. Remember
that with longer checkpoints, the odds of them calling
pg_start_backup during one and having to wait are much greater.
--
Jim Nasby                                            jim@nasby.net
EnterpriseDB      http://enterprisedb.com      512.569.9461 (cell)