Re: Auto-explain patch

Here is an updated version of the patch, with a debug_explain_min_duration
parameter to allow explaining of just slow-running queries. I've also incorporated
a couple of Simon Riggs' suggestions for formatting the output better.

Do I need to post this to -patches, or is that now obsolete?

Regards, Dean

----------------------------------------
> From: dean_rasheed(at)hotmail(dot)com
> To: badalex(at)gmail(dot)com
> CC: pgsql-hackers(at)postgresql(dot)org
> Subject: RE: [HACKERS] Auto-explain patch
> Date: Wed, 2 Jul 2008 19:42:06 +0000
>
>
>> Its certainly not useful to *me* in its current form. It would
>> produce way to much (usless) output. However if it were tied to
>> log_min_duration_statement so I get auto explains for long running
>> queries... That would be very useful indeed. Even if it has to
>> explain everything just to toss out the explain if it did not meet
>> log_min_duration_statement. Unless I missed something and thats
>> exactly what it does?
>
> Thanks for the feedback. I agree, it does need a way to limit the
> output, and target just the slow-running queries.
>
> I also remember now the problem I had last time:- since this debug
> output is produced at a lower level than the other statement logging
> (so it can explain *all* SQL executed, not just top-level statements), it
> is difficult to control using the normal statement logging parameters.
>
> It would be easy to add another parameter, debug_explain_min_duration,
> specific to this option, to limit it to slow low-level queries.
>
> This would allow setting debug_explain_min_duration to be smaller than
> log_min_duration_statement, which makes sense, since the latter
> controls logging of top-level statements which may result in multiple
> low-level queries.
>
> Doing it this way would mean instrumenting all queries, but only
> explaining the slow ones, when debug_explain_plan is on.
> I'll have a play and see how it goes...
>
> Regards, Dean
>
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