Mysql performance/optimization help

Question

So this was a small site that got extremely popular very fast and now and im having major problems with the below sql query.

I understand that my DB design is not great. I have text field for subjects and programs witch contains a serialized array and i search it using like.

the below query takes about a minute.

SELECT p.*, e.institution
FROM   cv_personal p
LEFT   JOIN cv_education e
ON     p.id = e.user_id
LEFT   JOIN cv_literacy l
ON     p.id = l.user_id
WHERE  1 = 1
AND    (e.qualification LIKE '%php%' OR e.subjects LIKE '%php%' OR l.programs LIKE '%php%')
GROUP  BY p.id
ORDER  BY p.created_on DESC

Answer 1

What an EXPLAIN show ? I think you can add conditions to a join to reduce number of records which are used :

SELECT p.*, e.institution
FROM   cv_personal p
LEFT   JOIN cv_education e
ON     (e.qualification LIKE '%php%' OR e.subjects LIKE '%php%') AND p.id = e.user_id
LEFT   JOIN cv_literacy l
ON     l.programs LIKE '%php%' AND p.id = l.user_id
ORDER  BY p.created_on DESC

And why do you use GROUP BY ?