How can i optimize MySQL's ORDER BY RAND() function?

Question

I\'d like to optimize my queries so I look into mysql-slow.log.

Most of my slow queries contains ORDER BY RAND(). I cannot find a real solu

Answer 1

This will give you single sub query that will use the index to get a random id then the other query will fire getting your joined table.

SELECT  accomodation.ac_id,
        accomodation.ac_status,
        accomodation.ac_name,
        accomodation.ac_status,
        accomodation.ac_images
FROM    accomodation, accomodation_category
WHERE   accomodation.ac_status != 'draft'
        AND accomodation.ac_category = accomodation_category.acat_id
        AND accomodation_category.acat_slug != 'vendeglatohely'
        AND ac_images != 'b:0;'
AND accomodation.ac_id IS IN (
        SELECT accomodation.ac_id FROM accomodation ORDER BY RAND() LIMIT 1
)