Question about search speed

[Ivan Smahin]

On Jan 28, 2013, at 3:33 PM, jda <jda at his.com> wrote:

> 
> I have a built-in search that finds the last 20 records entered. Each record has a unique sequential number (1..N) in the field "id", and this is the query:
> 
> 
>     SELECT * FROM mytable WHERE id > (select max(id) - 20 from mytable)
> 
> 
> It works, but is very slow. With a database of ~7000 records it takes ~20 seconds.
> 
> Is there a way to optimize this (using V4.9.1, Mac OS X).
> 


set @myvar = (select max(id) - 20 from mytable);
SELECT * FROM mytable WHERE id >  @myvar;
-- 
Best regards,
Ivan Smahin
Senior Software Engineer
Paradigma Software, Inc
Valentina - The Ultra-Fast Database
http://www.valentina-db.com