[ovirt-devel] Important changes in the Search Engine code

[Eli Mesika]

----- Original Message -----
> From: "Moti Asayag" <masayag at redhat.com>
> To: "Eli Mesika" <emesika at redhat.com>
> Cc: "engine-devel at ovirt.org" <devel at ovirt.org>
> Sent: Wednesday, March 11, 2015 11:53:50 AM
> Subject: Re: [ovirt-devel] Important changes in the Search Engine code
> 
> 
> 
> ----- Original Message -----
> > From: "Eli Mesika" <emesika at redhat.com>
> > To: "engine-devel at ovirt.org" <devel at ovirt.org>
> > Sent: Wednesday, March 11, 2015 10:48:44 AM
> > Subject: [ovirt-devel] Important changes in the Search Engine code
> > 
> > Hi All
> > 
> > We had in the past many cases in which the search engine returned duplicate
> > records.
> > Most of those cases are not simple to resolve in the DB layer by changing
> > the
> > query due to schema limitations.
> > We had decided to handle that by adding DISTINCT to the queries that the
> > search engine generates  [1]
> 
> Wouldn't that cause some penalty for each query ? Each navigation between
> tabs in
> the UI will become slower now that the returned values need to be sorted,
> even when
> not required ?

We had tested that for a while and  the penalty is relatively small.
We surely can come with a better solution but it requires heavy schema changes 
I think we can live with that ....

> 
> > However, we might have cases in which both DISTINCT and ORDER BY f({args})
> > (where f is a function call) is used
> > In that case, we will get SQL exception since the ORDER BY is applied on
> > the
> > DISTINCT result that does not include f as a field.
> > I had prevented using DISTINCT in such cases [2]
> > That means that you still may got duplicates in such cases and then you
> > should handle it in the same method as in [3]
> > (basically returning the function result in the select as a computed field)
> > 
> > 
> > [1] https://gerrit.ovirt.org/#/c/31896
> > [2] https://gerrit.ovirt.org/#/c/38459
> > [3] https://gerrit.ovirt.org/#/c/36946
> > 
> > 
> > Thanks
> > Eli Mesika
> > 
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> > 
>