An update on shared term splitting

Background reading: #30335 and the notes on shared term splitting in https://make.wordpress.org/core/2014/11/20/dev-chat-summary-november-19th/.

As part of the work on the taxonomy roadmap in 4.1, shared terms (terms which are shared across more than one taxonomyTaxonomy A taxonomy is a way to group things together. In WordPress, some common taxonomies are category, link, tag, or post format. https://codex.wordpress.org/Taxonomies#Default_Taxonomies. due to a slug collision) now get split when the term gets updated. The end result being that editing a term in one taxonomy will no longer affect the term in another taxonomy.

Many plugins store term IDs in post metaMeta Meta is a term that refers to the inside workings of a group. For us, this is the team that works on internal WordPress sites like WordCamp Central and Make WordPress., options, terms (!), etc, and the side effect of shared term splitting is that these caches can break when the ID of a term they reference changes. Not only that, but the breakage (and the cause) can be invisible to the user and hard to track down if they do notice it.

Following a discussion in #core Slack I’m proposing that shared term splitting is removed from 4.1 and we’ll add it back in for 4.2 and allow a full releaseRelease A release is the distribution of the final version of an application. A software release may be either public or private and generally constitutes the initial or new generation of a new or upgraded application. A release is preceded by the distribution of alpha and then beta versions of the software. cycle to get the word out to developers about the change. I’ll makemake A collection of P2 blogs at make.wordpress.org, which are the home to a number of contributor groups, including core development (make/core, formerly "wpdevel"), the UI working group (make/ui), translators (make/polyglots), the theme reviewers (make/themes), resources for plugin authors (make/plugins), and the accessibility working group (make/accessibility). the final decision during tomorrow’s dev chat.

Thanks in particular to @mboynes for his time spent on this.

(Note that this only affects existing terms; new terms do not get shared since r30240.)

#4-1, #dev-notes, #roadmap, #taxonomy