Question

I am writing a SQL query which requires highly optimized solution, so as to not timeout. But I have got no idea of how to continuously optimize the following SQL query:

select distinct j.job,f.path,p.path 
from fixes f, jobs j, paths p where f.job=j.id and p.id =f.path 
and (p.path like '//Tools/Web/%' or p.path = '//Tools/Web');

I have created indexes on the following fields(essentially everything):

• jobs.id
• jobs.job
• paths.path
• paths.id
• fixes.job
• fixes.path

In each of the "fixes", "jobs", "paths" table there are ~50,000 rows, and current timeout is 6 min

The ‘explain’ command shows the following information, try to deciphering

1   SIMPLE  j   index   PRIMARY         job     62   (null)    73226    Using index; Using temporary
1   SIMPLE  f   ref     path,job        job     8    j.id      825  
1   SIMPLE  p   eq_ref  PRIMARY,path    PRIMARY 8    f.path    1        Using where

The table creation statements for the ‘paths’ table:

CREATE TABLE `paths` (
   `id` bigint(20) NOT NULL AUTO_INCREMENT,
   `path` varchar(250) NOT NULL,
   PRIMARY KEY (`id`),
   UNIQUE KEY `path` (`path`),
 ) ENGINE=InnoDB  DEFAULT CHARSET=utf8;

Answer 1

Wouldn’t this get the same results?

select distinct j.job,f.path,p.path  
from fixes f
join  jobs j on  f.job=j.id 
join  paths p  on p.id =f.path  
where p.path like '//Tools/Web%' 

OR is almost always a costly feature.

You could also try a Union Query, they are often faster than an OR.

select  j.job,f.path,p.path  
from fixes f
join  jobs j on  f.job=j.id 
join  paths p  on p.id =f.path  
where p.path like '//Tools/Web/%' 
union 
select  j.job,f.path,p.path  
from fixes f
join  jobs j on  f.job=j.id 
join  paths p  on p.id =f.path  
where  p.path = '//Tools/Web');