Re: POC: Cache data in GetSnapshotData()

From: Robert Haas <robertmhaas(at)gmail(dot)com>
To: Mithun Cy <mithun(dot)cy(at)enterprisedb(dot)com>
Cc: Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>, Andres Freund <andres(at)anarazel(dot)de>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: POC: Cache data in GetSnapshotData()
Date: 2016-03-16 17:29:22
Message-ID: CA+TgmoYVdqPwsY_VpQoP4O2ZtQJ2-AOfJ1oMnK5Gi2EbMqE=BQ@mail.gmail.com
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On Wed, Mar 16, 2016 at 4:40 AM, Mithun Cy <mithun(dot)cy(at)enterprisedb(dot)com>
wrote:

>
> On Thu, Mar 3, 2016 at 6:20 AM, Mithun Cy <mithun(dot)cy(at)enterprisedb(dot)com>
> wrote:
> > I will continue to benchmark above tests with much wider range of
> clients.
>
> Latest Benchmarking shows following results for unlogged tables.
>
> clients BASE ONLY CLOG CHANGES % Increase CLOG CHANGES + SAVE SNAPSHOT %
> Increase
> 1 1198.326337 1328.069656 10.8270439357 1234.078342 2.9834948875
> 32 37455.181727 38295.250519 2.2428640131 41023.126293 9.5259037641
> 64 48838.016451 50675.845885 3.7631123611 51662.814319 5.7840143259
> 88 36878.187766 53173.577363 44.1870671639 56025.454917 51.9203038731
> 128 35901.537773 52026.024098 44.9130798434 53864.486733 50.0339263281
> 256 28130.354402 46793.134156 66.3439197647 46817.04602 66.4289235427
>

Whoa. At 64 clients, we're hardly getting any benefit, but then by 88
clients, we're getting a huge benefit. I wonder why there's that sharp
change there.

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

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