You are correct.
On Wed, 24 Mar 2004, Henrik Schröder wrote:
> I don't think it does right now, but that can always be taken care of later.
>
> Assuming that the query uses one index that contains all the where-columns
> and the orderby-columns, having an ORDER BY that sorts on expressions is
> still the biggest problem, right?
>
>
> /Henrik
>
> -----Original Message-----
> From: Victor Pendleton [mailto:vpendleton@stripped]
> Sent: den 24 mars 2004 16:22
> To: vpendleton@stripped; Henrik Schröder; 'mysql@stripped'
> Subject: Re: How to optimize ugly order by?
>
>
> Let me rephrase my statement. Does the index being used include the order by
> columns? If not, the optimizer will not be able to perform both row
> selection and row ordering in the same pass.
>
> On Wed, 24 Mar 2004, Victor Pendleton wrote:
> > Does the where clause contain the order by columns? If not, then you
> > will have a filesort no matter what.
> >
> > On Wed, 24 Mar 2004, Henrik Schröder wrote:
> > > Hi all,
> > >
> > > I have a table of users which contains a lot of information, and
> > > also a column called membershiptype which can either be 0, 1, or 2.
> > > This table is used a lot in various searches, and all results should
> > > be ordered by membership type, but the order should not be 0-1-2,
> > > but instead 1-2-0. Currently, this is achieved like this:
> > >
> > > SELECT ... ORDER BY (membershiptype <> 1) ASC, (membershiptype
> <> 2)
> > > ASC, login ASC
> > >
> > > ...which is rather ugly, and forces MySQL to create a temp table
> > > with tthe calculated expressions and then re-sort the result using
> > > these. Since this query is used a lot, it would be nice if I could
> > > get rid of this. I'm completely stumped. Any ideas?
> > >
> > > No, I did not choose the sort order. No, I can not change the values
> > > used. Yes, it has to be this sort order. :-)
> > >
> > >
> > > /Henrik Schröder
> > >
> > > --
> > > MySQL General Mailing List
> > > For list archives: http://lists.mysql.com/mysql
> > > To unsubscribe:
> http://lists.mysql.com/mysql?unsub=1
> >
> > --
> > MySQL General Mailing List
> > For list archives: http://lists.mysql.com/mysql
> > To unsubscribe:
> http://lists.mysql.com/mysql?unsub=1
