Query Optimization

[anu123]

Hi

 

I have a query

 

SELECT * FROM table1 AS a WHERE a.user_id NOT IN (SELECT c.user_id FROM table2 AS c) and (a.sentby = ‘S’ or a. sentby =’B’ or a. sentby = ‘R’)

 

This was running fine when the number of users in the site was less, but as the user number increased, the the query is taking too much time to run. Can anyone help me with how to optimize this query so that, the site wont get slow

 

Thanks in advance

[fenway]

Hard to tell without EXPLAIN output.

 

Try this:

 

SELECT 
* 
FROM table1 AS a 
LEFT JOIN table2 AS c USING ( user_id )
WHERE c.user_id IS NULL
and (a.sentby = ‘S’ or a. sentby =’B’ or a. sentby = ‘R’)