Re: Patch: add timing of buffer I/O requests

On Tue, Mar 27, 2012 at 8:41 PM, Greg Stark <stark@mit.edu> wrote:
> On Tue, Mar 27, 2012 at 7:58 PM, Robert Haas <robertmhaas@gmail.com> wrote:
>> I've committed the core of this.  I left out the stats collector
>> stuff, because it's still per-table and I think perhaps we should back
>> off to just per-database.  I changed it so that it does not conflate
>> wait time with I/O time.  Maybe there should be a separate method of
>> measuring wait time, but I don't think it's a good idea for the
>> per-backend stats to measure a different thing than what gets reported
>> up to the stats collector - we should have ONE definition of each
>> counter.  I also tweaked the EXPLAIN output format a bit, and the
>> docs.
>
> Maybe I missed some earlier discussoin -- I've been having trouble
> keeping up with the lists.
>
> But was there discussion of why this is a GUC? Why not just another
> parameter to EXPLAIN like the others?
> i.e. EXPLAIN (ANALYZE, BUFFERS, IOTIMING)

Because you want to be able to expose the data even for queries that
aren't explained.  Right now, you can do that with pg_stat_statements;
and the original patch also had per-table counters, but I didn't
commit that part due to some concerns about stats bloat.

--
Robert Haas
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