Re: Possible to find disk IOs for a Query?

On Wed, Aug 31, 2016 at 3:01 PM, Bobby Mozumder <bmozumder(at)gmail(dot)com> wrote:

> Is it possible to find the number of disk IOs performed for a query?
> EXPLAIN ANALYZE looks like it shows number of sequential rows scanned, but
> not number of IOs.
>
> My database is on an NVMe SSD, and am trying to cut microseconds of disk
> IO per query by possibly denormalizing.
>

Maybe helpful, altough slightly different since it works on an aggregate
basis:

If you set "track_io_timing=on" in your postgresql.conf, you can use
pg_stat_statements [1] to get I/O timings (i.e. how long a certain type of
query took for I/O access).

Typically I'd use this in combination with system-level metrics, so you can
understand which queries were running at the time of a given I/O spike.

[1] https://www.postgresql.org/docs/9.5/static/pgstatstatements.html

Best,
Lukas

--
Lukas Fittl

Skype: lfittl
Phone: +1 415 321 0630