Re: PLEASE GOD HELP US!

On Sat, 2004-10-02 at 09:14, Stephan Szabo wrote:
> On Fri, 1 Oct 2004, Scott Marlowe wrote:
>
> > On Fri, 2004-10-01 at 14:26, Shane | SkinnyCorp wrote:
> > > Okay, just so no one posts about this again...
> > >
> > > the 'ORDER BY t.status=5,lastreply' clause is meant to float the threads
> > > with a status of '5' to the top of the list... it is NOT meant to only grab
> > > threads where the status = 5.  Oh and believe me, when I take this out of
> > > the query, it CERTAINLY doesn't add any more than possible 1/4 of a
> > > millesecond to the speed of the SELECT statement.
> >
> >
> > Wouldn't this work just as well?
> >
> > SELECT * FROM thread_listing AS t ORDER BY t.status
> > DESC,t.lastreply desc LIMIT 25 OFFSET 0
>
> Probably not, because I don't think he wants the other statuses to have
> special ranking over the others, so a status=4 and status=1 row should be
> sorted by lastreply only effectively. This is the problem of combining
> separate status flags into a single field if you want to be doing these
> sorts of queries.
>

So would a union give good performance?  Just union the first 25 or less
with status=5 with the rest, using a 1 and 0 in each union to order by
first?  Hopefully the indexes would then be used.