Horton

Re: Speed up transaction completion faster after many relations are accessed in a transaction

David Rowley <david.rowley@2ndquadrant.com>

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From: David Rowley <david.rowley@2ndquadrant.com>
To: "Tsunakawa, Takayuki" <tsunakawa.takay@jp.fujitsu.com>
Cc: Andres Freund <andres@anarazel.de>, Tom Lane <tgl@sss.pgh.pa.us>, Peter Eisentraut <peter.eisentraut@2ndquadrant.com>, Amit Langote <Langote_Amit_f8@lab.ntt.co.jp>, "Imai, Yoshikazu" <imai.yoshikazu@jp.fujitsu.com>, Simon Riggs <simon@2ndquadrant.com>, "pgsql-hackers@lists.postgresql.org" <pgsql-hackers@lists.postgresql.org>
Date: 2019-04-08T02:58:43Z
Lists: pgsql-hackers 
On Mon, 8 Apr 2019 at 14:54, Tsunakawa, Takayuki
<tsunakawa.takay@jp.fujitsu.com> wrote:
>
> From: 'Andres Freund' [mailto:andres@anarazel.de]
> > Did you see that people measured slowdowns?
>
> Yeah, 0.5% decrease with pgbench -M prepared -S (select-only), which feels like a somewhat extreme test case.  And that might be within noise as was mentioned.
>
> If we want to remove even the noise, we may have to think of removing the LocalLockHash completely.  But it doesn't seem feasible...

It would be good to get your view on the
shrink_bloated_locallocktable_v3.patch I worked on last night. I was
unable to measure any overhead to solving the problem that way.

-- 
 David Rowley                   http://www.2ndQuadrant.com/
 PostgreSQL Development, 24x7 Support, Training & Services

Commits

  1. Reorder LOCALLOCK structure members to compact the size

  2. Be more careful to not lose sync in the FE/BE protocol.