Re: Joins and full index scans...mysql vs postgres?

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



ryan groth wrote:
I am issing a query like this:
SELECT *
   FROM users users
   LEFT JOIN phorum_users_base ON users.uid = phorum_users_base.user_id
   LEFT JOIN useraux ON useraux.uid = users.uid;



I'm not sure if postgres would rewrite your query to do the joins properly, though I guess someone else might've already suggested this :)


I'm probably wrong but I read that as:

join users -> phorum_users_base (ON users.uid = phorum_users_base.user_id)

join phorum_users_base -> useraux (ON useraux.uid = users.uid) which won't be indexable because u.uid doesn't exist in phorum_users_base.



Try

SELECT *
FROM users users
LEFT JOIN phorum_users_base ON users.uid = phorum_users_base.user_id
LEFT JOIN useraux ON useraux.uid = phorum_users_base.user_id

or

SELECT *
FROM users u, phorum_users_base pub, useraux ua WHERE u.uid = pub.user_id AND au.uid = u.uid AND pub.user_id=au.uid;


--
Postgresql & php tutorials
http://www.designmagick.com/


[Postgresql General]     [Postgresql PHP]     [PHP Users]     [PHP Home]     [PHP on Windows]     [Kernel Newbies]     [PHP Classes]     [PHP Books]     [PHP Databases]     [Yosemite]

  Powered by Linux