On Friday 12 October 2007, henk de wit <henk53602(at)hotmail(dot)com> wrote:
> > select payment_id from transactions order by payment_id desc limit 1;
>
> This one is indeed instant! Less than 50ms. In my case I can't use it for
> max though because of the fact that payment_id can be null (which is an
> unfortunate design choice). The other variant however didn't become
> instant. I.e. I tried:
>
> select time from transactions where payment_id = 67 order by time asc
> limit 1;
>
> But this one is still really slow.
If you had a compound index on payment_id,time (especially with a WHERE time
IS NOT NULL conditional) it would likely speed it up.
--
Ghawar is dying