On 09/03, Sean McGinnis wrote:
>
> > On Mar 9, 2018, at 07:37, TommyLike Hu <[email protected]> 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.

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