[openstack-dev] [glance] Why no DB index on sort parameters

Nikhil Komawar nikhil.komawar at RACKSPACE.COM
Tue Apr 21 14:55:38 UTC 2015

Rally is great overall however, we need good EXPLAIN examples on real world data. Smaller deployments might benefit from a simple sample performance analysis however, larger data sets can have impacts on areas that you never expect.

A spec means that we document the indices proposed in the code base, based on all of the use cases. The way I look at it, a patch is needed anyways and it (rally gate job) would get attention from reviewers when the patch is proposed.


From: Flavio Percoco <flavio at redhat.com>
Sent: Tuesday, April 21, 2015 10:48 AM
To: OpenStack Development Mailing List (not for usage questions)
Subject: Re: [openstack-dev] [glance] Why no DB index on sort parameters

On 21/04/15 14:39 +0000, Nikhil Komawar wrote:
>This is a good idea. We recently removed a unique constraint that may result
>into some queries being very slow especially those that involve "name"
>property. I would recommend sketching out a spec that identifies potential full
>table scans especially for queries that join over image_properties table.
>We should discuss there what other use cases look like rather than smaller
>feedback on the ML.

More thatn a spec, I'd be interested in seeing the patch with the
change up and the results reported in Rally.

I guess we'll need a spec anyway, although I'd probably be ok with a
good bug report here.

/me *shrugs*

>From: Mike Bayer <mbayer at redhat.com>
>Sent: Tuesday, April 21, 2015 9:45 AM
>To: openstack-dev at lists.openstack.org
>Subject: Re: [openstack-dev] [glance] Why no DB index on sort parameters
>On 4/21/15 2:47 AM, Ajaya Agrawal wrote:
>    Hi All,
>    I see that glance supports arbitrary sort parameters and the default is
>    "created_at" while listing images. Is there any reason why we don't have
>    index over these fields? If we have an index over these fields then we
>    would avoid a full table scan to do sorting. IMO at least the created_at
>    field should have an index on it.
>just keep in mind that more indexes will place a performance penalty on INSERT
>statements, particularly at larger volumes.  I have no idea if that is
>important here but something to keep in mind.
>    Cheers,
>    Ajaya
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Flavio Percoco

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