[nova] indices on shadow-able fields

Mohammed Naser mnaser at vexxhost.com
Tue Apr 9 02:51:47 UTC 2019


Hi everyone.

In continuing with the trend of interesting database issues, I've
found the following interesting thing.  It looks like we don't have
indices for all of our tables that can be large on the deleted field.
I think it would be beneficial *especially* for cases when the
archiving code runs.

The big ones that are huge users in terms of rows without index are
`instance_system_metadata` and `instance_extra`.
`instance_action_events` and `instance_actions` don't have any either.

I believe without this, it results in doing a full table scan during
the clean up which can become pretty resource intensive.

I'll defer to the Nova team on the best practice about this (or if
this is even a bug), but I just wanted to bring the attention to this
as I've had mild success trying to tame a large database and
leveraging the archive DB tooling.

Thanks,
Mohammed

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Mohammed Naser — vexxhost
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