# Comparing Two Large MySQL Tables

**URL:** https://forum.kirupa.com/t/comparing-two-large-mysql-tables/203640
**Category:** programming
**Created:** [October 12, 2006, 6:18pm UTC](https://forum.kirupa.com/t/comparing-two-large-mysql-tables/203640 "2006-10-12T18:18:55Z")
**Posts on this page:** 1
**Page:** 1

<div class="post-metadata">

### Author: ![StarXploser](https://yyz1.discourse-cdn.com/flex011/user_avatar/forum.kirupa.com/starxploser/32/875_2.png) [@StarXploser](https://forum.kirupa.com/u/StarXploser)
#### Post date: [October 12, 2006, 6:18pm UTC](https://forum.kirupa.com/t/comparing-two-large-mysql-tables/203640/1 "2006-10-12T18:18:55Z")

</div>

Hi,  
I have two tables, class\_current and class\_compjar

class\_current has 3 fields: package,class,bundle  
class\_compjar has 3 fields: package,class,compjar\_id

they both have about 25k rows

I’d like to find out the differences between them.

I ran a this JOIN query, and it completely froze my machine for several minutes, I had to restart my computer:

SELECT a.class,a.package FROM class\_current AS a LEFT JOIN class\_compjar AS b ON ( a.class=b.class AND a.package=b.package ) WHERE b.class IS NULL

or something like that, i dont remember the exact query but i’m pretty positive it was this one.

Is there a better way? Could someone point me in the right direction?  
Thanx in advance.Comparing Two Large Tables