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Re: Storing hot members of PGPROC out of the band

From: Robert Haas <robertmhaas(at)gmail(dot)com>
To: Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>
Cc: Simon Riggs <simon(at)2ndquadrant(dot)com>, Pavan Deolasee <pavan(dot)deolasee(at)gmail(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Storing hot members of PGPROC out of the band
Date: 2011-12-16 13:34:52
Message-ID: CA+TgmobxeA5g4j2GnpMq4ZsJCiiciQCLOoeO7kEhAa1ExmHobg@mail.gmail.com (view raw or flat)
Thread:
Lists: pgsql-hackers
On Thu, Dec 15, 2011 at 11:35 PM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
> One small detail I'm noticing on further review is that I've slightly
> changed the semantics here:
>
>            if (!TransactionIdIsNormal(xid)
>                || NormalTransactionIdPrecedes(xmax, xid))
>                    continue;
>
> That really ought to be testing <=, not just <.  That doesn't seem
> like it should affect correctness, though: at worst, we unnecessarily
> include one or more XIDs in the snapshot that will be ignored anyway.
> I'll fix that and rerun the tests but I don't think it'll make any
> difference.

New results with the attached, updated patch.  As predicted, these are
quite similar to the last batch...

m01 tps = 618.460567 (including connections establishing)
s01 tps = 628.394270 (including connections establishing)
m08 tps = 4558.930585 (including connections establishing)
s08 tps = 4490.285074 (including connections establishing)
m16 tps = 7577.677079 (including connections establishing)
s16 tps = 7582.611380 (including connections establishing)
m24 tps = 11556.680518 (including connections establishing)
s24 tps = 11527.982307 (including connections establishing)
m32 tps = 10807.216084 (including connections establishing)
s32 tps = 10871.625992 (including connections establishing)
m80 tps = 10818.092314 (including connections establishing)
s80 tps = 10866.780660 (including connections establishing)

Unlogged Tables:

m01 tps = 670.328782 (including connections establishing)
s01 tps = 818.666971 (including connections establishing)
m08 tps = 4793.337235 (including connections establishing)
s08 tps = 4888.600945 (including connections establishing)
m16 tps = 8016.092785 (including connections establishing)
s16 tps = 8123.217451 (including connections establishing)
m24 tps = 14082.694567 (including connections establishing)
s24 tps = 14114.466246 (including connections establishing)
m32 tps = 17881.340576 (including connections establishing)
s32 tps = 18291.739818 (including connections establishing)
m80 tps = 12767.535657 (including connections establishing)
s80 tps = 17380.055381 (including connections establishing)

-- 
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

Attachment: getsnapshotdata-tweaks-v2.patch
Description: application/octet-stream (2.7 KB)

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