Re: PATCH: regular logging of checkpoint progress

On 26 Srpen 2011, 9:54, Magnus Hagander wrote:
> This seems like the wrong thing to write to the log. It's really only
> useful *during* the checkpoint run, isn't it? If so, I think it should
> go in a pg_stat view. In theory, this could be the "progress view" or
> "progress field" talked about around Gregs previous patch - or it
> could just be modifying the commandstring in pg_stat_activity. Either
> way, it should be updated in shared memory in that case (like current
> query is), and not sent with a message to the collector.

I personally find it handy for example when I need to find out why
performance degraded at a certain point in the past. Now I can see there
was a checkpoint (thanks to log_checkpoints=on), but I don't know any
details about it's progress.

I already collect info from the pg_stat_bgwriter, that's why I thought I
could update it more often. The log file is a natural destination for such
information, IMHO. I see that as an extension to the current checkpoint
messages that are written to the log.

The commandstring approach is probably fine for interactive work, but not
very handy when you need to analyze something that already happened.
Unless you collected the data, of course.

Tomas