Post revisions

A revision is a copy of a post or page as it stood at one save. WordPress's documentation says the revisions system "stores a record of each saved draft or published update". You can step back through those copies, see what changed between them, and restore one. By default WordPress tracks changes to the title, author, content and excerpt.

Revisions are rows in the database's posts table, stored as children of the post they belong to, with the post type revision.

Revisions and autosaves

• A revision is made when you save a draft or update a published post. It is kept.
• An autosave is made by the editor while you work. There is at most one per user for a post, and each new one overwrites the last. It never overwrites the published content. If the browser crashes, WordPress offers the autosave back when you next open the post.

How often the editor autosaves is where the sources disagree. WordPress's glossary says changes are saved "every 2 minutes". The wp-config.php documentation says the default is 60 seconds, and the current source, default-constants.php, sets AUTOSAVE_INTERVAL to one minute. The source is what a site runs.

Where you meet it

In the editor. Open the Settings sidebar and stay on the Post or Page tab. A row named "Revisions" shows a count. Select the number. Since WordPress 7.0 that opens the revisions screen: a slider across the top, a list of saved revisions under a "Revision" tab, and two buttons, "Exit" and "Restore". Move the slider to the version you want and select "Restore".

The link "Open classic revisions screen" leads to the older view, where the button reads "Restore This Revision". In WordPress 6.9 and earlier, the number opens that view directly.

In wp-config.php. Two constants control the feature.

The wp-config.php generator writes the revisions line for you.

What goes wrong

• The database grows. With no limit, a page edited hundreds of times carries hundreds of rows, and WordPress has no screen for deleting them. How to clean up and optimize a WordPress database shows how to count them, remove them and cap them, and what that does and does not do for speed.
• Revisions were switched off. With WP_POST_REVISIONS set to false, there is no earlier version to return to after a bad edit. A number is the safer setting.
• The limit seems to do nothing. Setting a number does not trim what is already stored. A post's older revisions go the next time that post is updated.

The WordPress maintenance checklist says when revisions are worth clearing.

How to look at yours

With WP-CLI, this prints how many revisions the site holds:

wp post list --post_type=revision --format=count