Re: pg_stat_lwlocks view - lwlocks statistics, round 2

Tom Lane <tgl@sss.pgh.pa.us>

From: Tom Lane <tgl@sss.pgh.pa.us>
To: Alvaro Herrera <alvherre@2ndquadrant.com>
Cc: Robert Haas <robertmhaas@gmail.com>, Satoshi Nagayasu <snaga@uptime.jp>, Jeff Janes <jeff.janes@gmail.com>, Fujii Masao <masao.fujii@gmail.com>, Michael Paquier <michael.paquier@gmail.com>, pgsql-hackers@postgresql.org, Qi Huang <huangqiyx@hotmail.com>, Josh Berkus <josh@agliodbs.com>
Date: 2012-10-23T14:49:44Z
Lists: pgsql-hackers
Alvaro Herrera <alvherre@2ndquadrant.com> writes:
> Regarding Tom's objection to the fundamental issue of providing lwlocks
> data, I agree that maybe it's the wrong layer to be measuring to provide
> data to DBAs, but not providing any data is worse, because then even PG
> developers cannot know what are the real bottlenecks; and it's hard to
> see what other layer we need to be measuring.  Maybe this can serve as a
> foundation to discover useful things to provide in the future.

FWIW, I am not objecting to having the *ability* to collect such data.
I am questioning the usefulness/wisdom of having it turned on by
default, and I am also concerned about whether there is residual
overhead even when it's not turned on.

			regards, tom lane