In WordPress by default post revisions are enabled. WP saves a different version of page or post for each edit you make. It is a great feature and let you revert your edits as a specific edit. As number of post edits increases it makes database heavy. For example, You have edited a post 30 times and each revisions saved in database.
In this post I am going to explain how to disable revisions or at least lower down number of revisions saved in database.
For this you need to edit wp-config.php. It is located in root directory of WordPress Installation.Make sure you have made a back up of this file.
Disabling Post Revisions
Add this line of code in wp-config.php
define( 'WP_POST_REVISIONS', false );
Change Post Revisions
Add this line of code in wp-config.php . Here 10 is number of revision to save. It is always better to save upto 10.Again it is up to you.
define( 'WP_POST_REVISIONS', 10 );
I am sure it will lower down size of your db and lower down server load.