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On 09/03, Sean McGinnis wrote:
>
> > On Mar 9, 2018, at 07:37, TommyLike Hu <tommylikehu at gmail.com> wrote:
> >
> > Thanks Gorka,
> >     To be clear, I started this discussion not because I reject this feature, instead I like it as it's much more clean and simple, compared with performance impact it solves several other issues which we hate badly. I wrote this is to point out we may have this issue, and to see whether we could improve it before it's actually landed. Better is better:)
> >
> >
> >     - Using a single query to retrieve both counts and sums instead of 2
> >      queries.
> >
> > For this advice, I think I already combined count and sum into single query.
> >

Yes, but we would be doing 2 count and sum queries, one for the volumes
and another one for the per volume types, the idea I was proposing is
doing just 1 query for both calculations, that way even if you increase
the payload of the response from the DB you are getting rid of a round
trip to the DB as well as a pass through  all the volumes for the volume
type.



> >  - DB triggers to do the actual counting.
> >
>
> Please, no DB triggers. :)
>
> > This seems a good idea, but not sure whether it could cover all of the cases we have in our quota system and whether can be easily integrated into cinder, can you share more detail on this?
> >
> > Thanks
> > TommyLike
> >
>


As a general rule I agree with Sean that it's better to not have
triggers, but I wanted to mention them as an alternative in case we
really, really, really have problems with the other alternatives.

Cheers,
Gorka.