Fields that will become unused with MCR schema migration should be hidden in the toolforge replica of the wikidatabases, to avoid tools from reading incomplete/inconsistent data. These fields will eventually be dropped anyway, and will stop to be updated when T198312 is done, which is expected to happen by the end of the year [[https://docs.google.com/spreadsheets/d/1TkznqoaMH6HTQBSMxXPRhSOo8auf1oMLx6c-Cjjf-Sk/edit?ts=5b43c255#gid=0|MCR migration plan]]. Affected fields are:
page.page_content_model
revision.rev_content_model
revision.rev_content_format
revision.rev_text_id
These fields should become unavailable on toolforge soon, following an appropriate notice period.
NOTE: this ticket originally asked for compatibility to be maintained by adding joins to the views for the page and revision table. This idea has been dropped due to performance issues, see T195515.