Multiple _encloseme entries in postmeta table when disabling pings

[rebasaurus]

When we disable pings, this can lead to potentially hundreds of thousands rows accumulating with the _encloseme key on the postmeta table (as it is fired on every publish_post hook: ​https://github.com/WordPress/WordPress/blob/71cf332e6569f0ac2f263ce9b2168644942f5534/wp-includes/post.php#L6580) and therefore, cause performance issues on simple meta queries that are normally run on pageload:

SELECT post_id, meta_key, meta_value FROM wp_postmeta WHERE post_id IN (x) ORDER BY meta_id ASC

This is because the cleanup function do_all_pings() does not run anymore on the do_pings hook: ​https://github.com/WordPress/WordPress/blob/1e925a5ae3faccad31c48c810af3954d01a60f0e/wp-includes/comment.php#L2626

[rebasaurus]

We can utilize the 4th parameter of add_post_meta() to prevent duplicate entries.

[whyisjake]

@rebasaurus,

Thanks for contributing this issue, and the associated patch. To get this included in 5.3, we should look at adding some unit tests, and maybe a cleanup routine during the upgrade.

[whyisjake]

Chatting with @jorbin, cleanup could be part of the upgrade routine or maybe a standalone plugin.

[whyisjake]

This probably should have been update_post_meta() in the beginning...

[whyisjake]

The test I added isn't passing, just wanted to share as a starting for deeper testing, or another pass on the primary function. FWIW, changing to update_post_meta() is showing the same issue.

[whyisjake]

Ran this with @desrosj yesterday, tests are passing for him. I would love to get this committed and in beta 3.

[johnbillion]

The test isn't passing for me, so either the test is faulty or the patch is. I'm still seeing multiple _encloseme meta entries for the test post created in test_publish_post_hook().

Investigating.

[johnbillion]

False alarm! Looks good.

[johnbillion]

In 46426:

Pings/Trackbacks: Avoid adding multiple _pingme and _encloseme meta entries to a post when it gets updated prior to pings being done.

Props rebasaurus, whyisjake

Fixes #48014

[johnbillion]

In 46428:

Pings/Trackbacks: Remove a failing test that won't pass as long as WP_IMPORTING gets set during tests.

The _publish_post_hook() function checks for WP_IMPORTING before setting meta fields fir enclosures and pings, which means this test is doomed to fail.

The test can be re-implemented if the WP_IMPORTING constant gets moved to a function similar to how wp_installing() works for the WP_INSTALLING constant.

See #48014