There's an abandoned change that does this: https://gerrit.wikimedia.org/r/#/c/98252/

The abandon message is "No longer support for this change set." Any idea why?

In T65318#1055760, @jayvdb wrote:

The abandon message is "No longer support for this change set." Any idea why?

The patch set was open for 6 months to review, but was not succesfully reviewed. After the 6 months I have abandon the patch set, because I did not want give longer support for that (rebasing for example). But I also give the sentence "Feel free to resubmit and/or modify under your own name.", so this task is open for implemenation, do your own or use the already existing patch set and try to apply to master.

The protected_titles table holds essentially the same information as page_restrictions, but the structures of the tables are fundamentally different. page_restrictions holds some information specific to existing pages, which is understandable. protected_titles has some unnecessary columns:

• pt_user (the user who protected the title, note that page_restrictions.pr_user is reserved for per-user restrictions and currently unused)
• pt_reason
• pt_timestamp

Similarly, the Special:ProtectedTitles and Special:ProtectedPages pages provide fundamentally different information: the former selects from the protected_titles page itself, while the latter selects from the logging table.

I'd suggest to migrate Special:ProtectedTitles to use logging as well (all the info is already available there) and drop the unnecessary columns.