2

[MySQL] Deleting/Updating Rows Common To 2 Tables – Speed And Slave Lag Considerations


Posted by Artem Russakovskii on May 11th, 2009 in Databases, Programming

Introduction

A question I recently saw on Stack Overflow titled Faster way to delete matching [database] rows? prompted me to organize my thoughts and observations on the subject and quickly jot them down here.

Here is the brief description of the task: say, you have 2 MySQL tables a and b. The tables contain the same type of data, for example log entries. Now you want to delete all or a subset of the entries in table a that exist in table b.

Solutions Suggested By Others

DELETE FROM a WHERE EXISTS (SELECT b.id FROM b WHERE b.id = a.id);
 
DELETE a

…

Read the rest of this article »