[wp-trac] [WordPress Trac] #25233: Revisions metabox improvements

[WordPress Trac]

#25233: Revisions metabox improvements
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 Reporter:  jkudish       |      Owner:
     Type:  defect (bug)  |     Status:  new
 Priority:  normal        |  Milestone:  Awaiting Review
Component:  Revisions     |    Version:
 Severity:  normal        |   Keywords:  needs-patch
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 The revisions metabox suffers from performance degradation when unlimited
 revisions are allowed and a large amount of revisions (e.g. 600+) is
 achieved on a post.

 Symptoms:

 * Slow wp-admin page loads
 * Out of memory errors and 500 errors.

 This seems to be mainly due to:

 * All revisions are loaded at once when a post is loaded in wp-admin
 * For each revision, the entire `$post` object is loaded, when only a few
 pieces of information are needed
 * The queries in `get_children()` are not cached

 Proposed solution:

 * Rewrite the revisions meta box to load the revisions via ajax instead of
 with the initial page load, possibly with pagination or some kind of
 infinite scroll.
 * Only load the information required and not the entire `$post` object for
 each revision.
 * Cache the queries involved.

 Possible bottlenecks:

 * The `get_children()` and `wp_get_post_revisions()` functions are used in
 a bunch of different places, so it might be difficult to bake in
 compatibility for everything. Might be easier to create some new functions
 for the metabox specifically.
 * Currently WordPress loads all the revsions in order to possibly upgrade
 them to the 3.6 versioning of revisions. It does so on every post loaded
 in wp-admin. It might make sense to move this to an upgrade routine or
 somewhere else as it adds to the performance degradation.

 If this sounds like a good approach I'd be happy to work on a patch.

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Ticket URL: <http://core.trac.wordpress.org/ticket/25233>
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