At 11:01 AM 5/23/2003, Egor Egorov wrote:
> > I'm having a problem with MySQL and ORDER BY.
> >
> > With this statement, extra = "Using where"
> >
> > EXPLAIN SELECT * FROM c1 LEFT JOIN c2 ON c1.id = c2.id WHERE c1.id = '21'
> >
> > Simply adding "ORDER BY c1.size DESC" changes the extra
> > to "Using where; Using filesort".
> >
> > Naturally I have an index on c1.id (c2.id also has an index), and
> > c1.size.
> >
> > I'm at a loss as to why it's going to filesort. The query speed
> > is quick on most results, except for when there is > ~10,000 matches,
> > then it can take several seconds to process. Most matches are
> > under 1,000 results, though some can be as high as 150,000.
> >
> > Is there anything I can do to remove use of filesort, or increase
> > the speed of the query on large matches?
>
>What version do you use? 3.23.xx ? If so, you can upgrade to 4.0.x. In 4.0.x
>MySQL can use index in ORDER BY .. DESC queries.
Egor,
I'm running mysql-standard-4.0.12. The machine is a 2.4ghz server w/
1 gig of ram. I have been screwing around with the conf settings, heres
some of the settings:
set-variable = query_cache_type=1
set-variable = query_cache_size=2M
set-variable = max_connections=512
set-variable = low-priority-updates=ON
set-variable = key_buffer=256M
set-variable = max_allowed_packet=1M
set-variable = table_cache=512
set-variable = sort_buffer=5M
set-variable = read_rnd_buffer=5M
set-variable = record_buffer=3M
set-variable = myisam_sort_buffer_size=64M
set-variable = thread_cache=8
set-variable = thread_concurrency=2
Any help is appreciated.
Jason
