Re: [Tracker] HitsAdded, HitsRemoved and HitsModified for Xesam

[Philip Van Hoof <spam pvanhoof be>]

On Wed, 2008-04-30 at 11:05 -0400, Jamie McCracken wrote:

> > The best mechanism is simply reusing the same mechanism that was used
> > initially. And that is the query that we converted from the Xesam XML
> > stuff into the SQL query used to get the GetHits/GetHitsData and fed to
> > us during the NewSearch.
>
> yes of course - the live query result will be stored in a tmp table
> along with its sql, service types and mime types affected

Aha, here's the disconnect then. Can you elaborate on how this should be
implemented (the temporary table) and why it's necessary?

> Determining if a query is affected will need to check service and mime 
> types to see if they affect query

Because we can also equally easily determine whether a live-search is
affected by joining a table that contains "affected ServiceIDs", which
I'd call "Events", together with Services: Only the ones in "Events"
will be evaluated against the live-query.

No need to create any temporary tables, that way.

We only store (and per frequency dispose) "events" and we don't copy all
currently matching items of a live-query to a temporary table.

This way, a live-query doesn't consume memory in that temporary table
when it's just sitting there, doing nothing (and no indexing is
happening, in which case the indexer causes the changed items between
the last periodic handle and 'now()' to have their ServiceIDs in the
Events table).



> > Else we'll be throwing all HitsAdded, HitsRemoved and HitsModified to
> > all live queries (because there's no way to determine whether or not the
> > live query we're currently evaluating was affected by a specific event).
> >
> > So the "iterate over that list and determine if live query needs
> > refreshing" is a hard problem to solve ;-), it's not simply.
>
> I know - its easy to do hard to get it optimal :)

Voila :)



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