Re: [Tracker] What's the fast method to get partial items after sorting.

[Ivan Frade <ivan frade gmail com>]

hi, Zhenquiang

On 3/12/10, Chen, Zhenqiang <zhenqiang chen intel com> wrote:
> I have lots of photos. I want to get part of them after sorting. I use
> series of queries like:
>
> tracker-sparql -q "SELECT ?photo WHERE{?photo a nmm:Photo} ORDER BY
> ASC(?photo) OFFSET 1000 LIMIT 100"
> ...
> tracker-sparql -q "SELECT ?photo WHERE{?photo a nmm:Photo} ORDER BY
> ASC(?photo) OFFSET 2000 LIMIT 100"
>
> "Order" seams expensive in tracker.
> How to use index? What's the best way to do it?

Those queries look pretty useless, you are getting a list of sorted
uris of pictures (generated uris, not even the real location). You are
sorting a list like "urn:uuid:1273628", "urn:uuid:98377273", ...

your usage of offse and limit is fine though. We cannot help with the
performance of such a "laboratory" query. could you try with a more
realistic example?

regards,

ivan

> Thanks!
> -Zhenqiang