Horton

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

Tsunakawa, Takayuki <tsunakawa.takay@jp.fujitsu.com>

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From: "Tsunakawa, Takayuki" <tsunakawa.takay@jp.fujitsu.com>
To: 'Andres Freund' <andres@anarazel.de>
Cc: 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>, "David Rowley" <david.rowley@2ndquadrant.com>, "pgsql-hackers@lists.postgresql.org" <pgsql-hackers@lists.postgresql.org>
Date: 2019-04-08T02:54:16Z
Lists: pgsql-hackers 
From: 'Andres Freund' [mailto:andres@anarazel.de]
> On 2019-04-08 02:28:12 +0000, Tsunakawa, Takayuki wrote:
> > I think the linked list of LOCALLOCK approach is natural, simple, and
> > good.
> 
> 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...


Regards
Takayuki Tsunakawa

Commits

  1. Reorder LOCALLOCK structure members to compact the size

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