| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | David Rowley <david(dot)rowley(at)2ndquadrant(dot)com> |
| Cc: | Andrew Dunstan <andrew(dot)dunstan(at)2ndquadrant(dot)com>, Jeff Janes <jeff(dot)janes(at)gmail(dot)com>, Jeremy Schneider <schnjere(at)amazon(dot)com>, Joe Conway <mail(at)joeconway(dot)com>, Peter Geoghegan <pg(at)bowt(dot)ie>, PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org> |
| Subject: | Re: Should we increase the default vacuum_cost_limit? |
| Date: | 2019-03-09 16:31:36 |
| Message-ID: | 21148.1552149096@sss.pgh.pa.us |
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| Lists: | pgsql-hackers |
David Rowley <david(dot)rowley(at)2ndquadrant(dot)com> writes:
> I agree that vacuum_cost_delay might not be granular enough, however.
> If we're going to change the vacuum_cost_delay into microseconds, then
> I'm a little concerned that it'll silently break existing code that
> sets it. Scripts that do manual off-peak vacuums are pretty common
> out in the wild.
True. Perhaps we could keep the units as ms but make it a float?
Not sure if the "units" logic can cope though.
> My vote is to 10x the maximum for vacuum_cost_limit and consider
> changing how it all works in PG13. If nothing happens before this
> time next year then we can consider making vacuum_cost_delay a
> microseconds GUC.
I'm not really happy with the idea of changing the defaults in this area
and then changing them again next year. That's going to lead to a lot
of confusion, and a mess for people who may have changed (some) of
the settings manually.
regards, tom lane
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