Every time I edit a post or page, WP keeps a copy of the old version in my database. It is a great feature, handy when I mess up and need to revert to the previous version. But once my post or page is final, I have no use for the prior revisions. By default, WP keeps all the old versions, forever, and they can add up over time. I recently checked one of my sites and was surprised to find 3,566 useless old pages cluttering up my database. A large, cluttered database slows my site, as the server takes longer to retrieve information.
I should always make sure I have an up-to-date backup of my site. This is especially true before doing any database maintenance. I never know when something could go horribly wrong.
To clean out old posts and pages, as well as other database clutter, I can use a popular free plugin called WP-Optimize. Once all the clutter is removed, WP-Optimize can defragment/compact the database tables for optimum efficiency. Since my site is on a LiteSpeed server I could also use similar functionality provided by the excellent LiteSpeed Cache plugin.
I can limit the number of future page and post revisions that are saved by adding a line to wp-config.php. In my case, I save the latest two revisions: define('WP_POST_REVISIONS', 2);
Update (2018-07-18): Another cause of database clutter is deleted plugins. A well-behaved plugin should clean up after itself – giving me the option of removing all its data from my database when I delete it. Many plugins are not so polite. Deleting the plugin removes only the files, leaving now-useless database tables behind. A tool that can help with this is Plugins Garbage Collector. After making sure I have an up-to-date DB backup, I can run PGC to search my DB for tables left behind by deleted plugins, then remove those tables.
