Question

I’m trying to get an explain command to work in mysql. I am trying to troubleshoot the performance of this delete query:

DELETE FROM boost_cache_relationships
WHERE base_dir = 'cache/normal/www.dane101.com'
    AND page_callback = 'node'
    AND page_type = 'story'
    AND page_id = '2891';

This query is the output from a SHOW FULL PROCESSLIST command.

I understand that EXPLAIN does not work with delete so I copied it and replaced DELETE with SELECT to give the following:

explain select
FROM boost_cache_relationships
WHERE base_dir = 'cache/normal/www.dane101.com'
    AND page_callback = 'node'
    AND page_type = 'story'
    AND page_id = '2891';

When I hit enter, mysql gives me an error message that this is invalid SQL:

ERROR 1064 (42000): You have an error in your SQL syntax; check the
manual that corresponds to your MySQL server version for the right
syntax to use near ‘FROM boost_cache_relationships WHERE base_dir =
‘cache/normal/www.dane101.com’ A’ at line 1

What am I doing wrong?

Answer 1

You need to specify a field list:

select * FROM boost_cache_relationships WHERE base_dir = 'cache/normal/www.dane101.com' AND page_callback = 'node' AND page_type = 'story' AND page_id = '2891';