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Based on Michael Adams wp-testers email list post


Limit the number of posts revisions that WordPress stores in the database.

define( 'WP_POST_REVISIONS', 3 );


There is only ever a maximum of one autosave for any given post. New autosaves overwrite old autosaves. This means that no, your tables do not grow by one row every 60 seconds.

Autosaves are enabled for all posts and pages but do not overwrite published content. Autosaves are stored as a special type of revision; they do not overwrite the actual post. In fact, if your browser does crash, when you go to edit that post, WP will toss up a warning that says something like "This post has an autosave which is more recent that the post itself. Would you like to see it?" With a link to the revision page from where it can be restored/ignored.

Revision Options

There are options, but they are hidden well :) There is a constant (not even filterable) that can be set by a plugin or in your wp-settings.php file:


  • true (default), -1: store every revision
  • false, 0: do not store any revisions (except the one autosave per post)
  • (int) > 0: store that many revisions (+1 autosave) per post. Old revisions are automatically deleted.

Revision Storage Method

Revisions are stored in the posts table. I don't yet know what kind of impact that will have on post queries. We're going to turn the switch to "on" on sometime soonish and we'll have a better idea about what kind of damage, if any, it does.

Revisions are stored as children of their associated post (the same thing we do for attachments). They are given a post_status of 'inherit', a post_type of 'revision', and a post_name of {parent ID}- revision(-#) for regular revisions and {parent ID}-autosave for autosaves.

Plugins can customize what fields (within limits) are versioned. By default, WP keeps track of the changes to title, author, content, excerpt.

Revision Management

Deleting: There is an API function to delete revisions, but there is no UI. That can certainly change.

Andrew proposed a delete button in the actions column. A column of checkboxes and some action buttons at the top would be more in keeping with the current WP UI (like the Manage -> Posts page), but that would be totally confusing with the column of radio buttons and the "Compare" button we currently have. Andrew's suggestion is clean and simple. If any one wants to rethink that whole UI, please go ahead. Send some mockups to the list.

Re-editing by Contributer: I have no idea what happens in WP 2.5 when a Contributor edits an already published post (by that user or by another) :)

I can say, though, that nothing fancy happens with revisions in that scenario (unless the good will of some unforeseen bug rears its serendipitous head).

Creating new not-yet-to-be-published revisions for a currently published post / pinning an old revision: No. I honestly haven't a clue how many users would use this feature. Maybe everybody, maybe nobody. I don't think the code would be too hard to implement as a plugin given the new revisions API functions. The UI sounds difficult to me to get right.

If it is truly useful to our user base, we can certainly make it happen for core. I'm sure we'll get feedback from "real users" at when it gets turned on.

Displaying Rendered Revisions

Andrew mentioned the possibility of showing revisions in "raw" or "rendered" form. That seems like a good idea to me.

We had also discussed the possibility of showing old revisions and diffs on the blog itself. That certainly wouldn't appeal to everyone. I think that can be left to themers/plugin writers. All the pieces for it are already in core.