| From: | Jim Nasby <Jim(dot)Nasby(at)BlueTreble(dot)com> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>, Stephen Frost <sfrost(at)snowman(dot)net>, Joel Jacobson <joel(at)trustly(dot)com>, Pg Hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: pg_stat_activity.waiting_start |
| Date: | 2016-12-28 18:03:46 |
| Message-ID: | da4f9739-1d82-d1a9-55d1-1c97ea80811a@BlueTreble.com |
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| Lists: | pgsql-hackers |
On 12/28/16 11:25 AM, Tom Lane wrote:
> The idea of just capturing the wait start for heavyweight locks, and
> not other lock types, still seems superior to any of the alternatives
> that have been suggested ...
Is some kind of alarm a viable option for the others? If setting the
alarm is cheap, you could just set one for say 5ms when you have to wait
on a lock. If setting one is too expensive perhaps one could be set at
transaction start that looks at a global (and the global would be set
when a wait started). Obviously that means there's inaccuracy to the
true time spent waiting, but I think that's certainly fine for
pg_stat_activity. Most importantly, it would mean that if something has
gone horribly wrong you'd at least have some kind of relatively accurate
duration to work from.
--
Jim Nasby, Data Architect, Blue Treble Consulting, Austin TX
Experts in Analytics, Data Architecture and PostgreSQL
Data in Trouble? Get it in Treble! http://BlueTreble.com
855-TREBLE2 (855-873-2532)
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