| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Andres Freund <andres(at)anarazel(dot)de> |
| Cc: | David Rowley <david(dot)rowley(at)2ndquadrant(dot)com>, "Tsunakawa, Takayuki" <tsunakawa(dot)takay(at)jp(dot)fujitsu(dot)com>, "pgsql-hackers(at)lists(dot)postgresql(dot)org" <pgsql-hackers(at)lists(dot)postgresql(dot)org> |
| Subject: | Re: Speed up transaction completion faster after many relations are accessed in a transaction |
| Date: | 2019-02-19 00:01:06 |
| Message-ID: | 12317.1550534466@sss.pgh.pa.us |
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| Lists: | pgsql-hackers |
Andres Freund <andres(at)anarazel(dot)de> writes:
> Isn't a large portion of benefits in this patch going to be mooted by
> the locking improvements discussed in the other threads? I.e. there's
> hopefully not going to be a ton of cases with low overhead where we
> acquire a lot of locks and release them very soon after. Sure, for DDL
> etc we will, but I can't see this mattering from a performance POV?
Mmm ... AIUI, the patches currently proposed can only help for what
David called "point lookup" queries. There are still going to be
queries that scan a large proportion of a partition tree, so if you've
got tons of partitions, you'll be concerned about this sort of thing.
> I'm not against doing something like Tom proposes, but heuristics with
> magic constants like this tend to age purely / are hard to tune well
> across systems.
I didn't say it had to be a constant ...
regards, tom lane
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