Horton

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

Tom Lane <tgl@sss.pgh.pa.us>

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Andres Freund <andres@anarazel.de>
Cc: "Tsunakawa, Takayuki" <tsunakawa.takay@jp.fujitsu.com>, "pgsql-hackers@lists.postgresql.org" <pgsql-hackers@lists.postgresql.org>
Date: 2019-02-19T00:24:54Z
Lists: pgsql-hackers 
Andres Freund <andres@anarazel.de> writes:
> On 2019-02-18 18:42:32 -0500, Tom Lane wrote:
>> Do we really want a dlist here at all?  I'm concerned that bloating
>> LOCALLOCK will cost us when there are many locks involved.  This patch
>> increases the size of LOCALLOCK by 25% if I counted right, which does
>> not seem like a negligible penalty.

> It's currently [ 80 bytes with several padding holes ]
> seems we could trivially squeeze most of the bytes for a dlist node out
> of padding.

Yeah, but if we want to rearrange the members into an illogical order
to save some space, we should do that independently of this patch ---
and then the overhead of this patch would be even worse than 25%.

			regards, tom lane

Commits

  1. Reorder LOCALLOCK structure members to compact the size

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