| From: | Alexander Korotkov <a(dot)korotkov(at)postgrespro(dot)ru> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | Peter Geoghegan <pg(at)bowt(dot)ie>, Andres Freund <andres(at)anarazel(dot)de>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Display number of heap accesses for index scans |
| Date: | 2017-11-06 11:14:51 |
| Message-ID: | CAPpHfdtQT51jJn3BJSsOcgJvsJbN1ntVEPzQc80nOojqvzW+_g@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Mon, Nov 6, 2017 at 6:33 AM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Peter Geoghegan <pg(at)bowt(dot)ie> writes:
> > Andres Freund <andres(at)anarazel(dot)de> wrote:
> >> The number of index lookups that failed to return anything can be a
> >> critical performance factor in OLTP workloads. Therefore it seems like
> >> it'd be a good idea to extend the explain analyze output to include that
> >> information.
>
> > I certainly agree.
>
> Doesn't the EXPLAIN (BUFFERS) output already address this?
>
In plain index scan EXPLAIN (ANALYZE, BUFFERS) doesn't distinguish buffers
accessed in index and buffers accessed in heap
------
Alexander Korotkov
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company
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