Re: Patch for fast gin cache performance improvement

From: Ian Link <ian(at)ilink(dot)io>
To: Kevin Grittner <kgrittn(at)ymail(dot)com>
Cc: pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Patch for fast gin cache performance improvement
Date: 2013-06-18 18:41:36
Message-ID: 51C0A9E0.5080400@ilink.io
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No worries! I'll just wait until it's up again.
Thanks
Ian
> Kevin Grittner <mailto:kgrittn(at)ymail(dot)com>
> Tuesday, June 18, 2013 9:15 AM
>
> Oops -- we seem to have a problem with new community logins at the
> moment, which will hopefully be straightened out soon. You might
> want to wait a few days if you don't already have a login.
>
> --
> Kevin Grittner
> EnterpriseDB: http://www.enterprisedb.com
> The Enterprise PostgreSQL Company
> Kevin Grittner <mailto:kgrittn(at)ymail(dot)com>
> Tuesday, June 18, 2013 9:09 AM
> Ian Link<ian(at)ilink(dot)io> wrote:
>
>> This patch contains a performance improvement for the fast gin
>> cache.
>
>> Our test queries improve from about 0.9 ms to 0.030 ms.
>
> Impressive!
>
>> Thanks for reading and considering this patch!
>
> Congratulations on your first PostgreSQL patch! To get it
> scheduled for review, please add it to this page:
>
> https://commitfest.postgresql.org/action/commitfest_view/open
>
> You will need to get a community login (if you don't already have
> one), but that is a quick and painless process. Choose an
> appropriate topic (like "Performance") and reference the message ID
> of the email to which you attached the patch. Don't worry about
> the fields for reviewers, committer, or date closed.
>
> Sorry for the administrative overhead, but without it things can
> fall through the cracks. You can find an overview of the review
> process with links to more detail here:
>
> http://wiki.postgresql.org/wiki/CommitFest
>
> Thanks for contributing!
>
> Ian Link <mailto:ian(at)ilink(dot)io>
> Monday, June 17, 2013 9:42 PM
> *
>
> This patch contains a performance improvement for the fast gin cache.
> As you may know, the performance of the fast gin cache decreases with
> its size. Currently, the size of the fast gin cache is tied to
> work_mem. The size of work_mem can often be quite high. The large size
> of work_mem is inappropriate for the fast gin cache size. Therefore,
> we created a separate cache size called gin_fast_limit. This global
> variable controls the size of the fast gin cache, independently of
> work_mem. Currently, the default gin_fast_limit is set to 128kB.
> However, that value could need tweaking. 64kB may work better, but
> it's hard to say with only my single machine to test on.
>
>
> On my machine, this patch results in a nice speed up. Our test queries
> improve from about 0.9 ms to 0.030 ms. Please feel free to use the
> test case yourself: it should be attached. I can look into additional
> test cases (tsvectors) if anyone is interested.
>
>
> In addition to the global limit, we have provided a per-index limit:
> fast_cache_size. This per-index limit begins at -1, which means that
> it is disabled. If the user does not specify a per-index limit, the
> index will simply use the global limit.
>
>
> I would like to thank Andrew Gierth for all his help on this patch. As
> this is my first patch he was extremely helpful. The idea for this
> performance improvement was entirely his. I just did the
> implementation. Thanks for reading and considering this patch!*
>
>
> Ian Link

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