Dnia 23-10-2005, nie o godzinie 09:31 -0700, Craig A. James napisał(a):
<cut>
> MIN() and MAX() -- These are surprisingly slow, because they seem to do a full table scan EVEN ON AN INDEXED COLUMN!
In 8.1 this is no true, see the changelog.
> I don't understand why, but happily there is an effective substitute:
>
> select mycolumn from mytable order by mycolumn limit 1; -- same as MIN()
>
> select mycolumn from mytable order by mycolumn desc limit 1; -- same as MAX()
In 8.1 these queries are equivalent:
select mycolumn from mytable order by mycolumn limit 1;
select min(mycolumn) from mytable;
--
Tomasz Rybak <bogomips@post.pl>