Main limitations

Moved to Store.

Short strings

Moved to Store, which states the 768-character limit and why MySQL sets it.

Indexes

Moved to Optional MySQL Indexes and Optional Oracle Indexes.

Sanity Checks

Moved to Check the Database for Inconsistencies, which carries both scripts and says which of their checks need interpreting on a current instance.

Database browsing

Not carried over: a recommendation of one third-party SQL client, with nothing specific to XWiki.

DbVisualizer

Not carried over, with the section above.