| From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
|---|---|
| To: | "Yotsunaga, Naoki" <yotsunaga(dot)naoki(at)jp(dot)fujitsu(dot)com> |
| Cc: | Bruce Momjian <bruce(at)momjian(dot)us>, Phil Florent <philflorent(at)hotmail(dot)com>, Michael Paquier <michael(at)paquier(dot)xyz>, Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com>, "pgsql-hackers(at)lists(dot)postgresql(dot)org" <pgsql-hackers(at)lists(dot)postgresql(dot)org> |
| Subject: | Re: [Proposal] Add accumulated statistics |
| Date: | 2019-01-10 20:42:06 |
| Message-ID: | CA+TgmobQqvFvtZPneDELTW3KYWcmV6=cw6Vm9cs4tuCfUO=e8g@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Thu, Dec 20, 2018 at 8:48 PM Yotsunaga, Naoki
<yotsunaga(dot)naoki(at)jp(dot)fujitsu(dot)com> wrote:
> If so, is not that the number of wait events is useful information?
My theory is that the number of wait events is NOT useful information,
or at least not nearly as useful the results of a sampling approach.
The data that LWLOCK_STATS produce are downright misleading -- they
lead you to think that the bottlenecks are in different places than
they really are, because the locks that produce the most waiting can
be 5th or 10th in terms of the number of wait events.
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
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