The database layout documentation includes a big diagram of the MediaWiki tables. This is a redirect on commons to a diagram of the DB tables in MediaWiki release 1.20, built in 2012.
I think there has only been one major table change since then (new sites table) but there have been many small tweaks.
The SVG file on commons has fantastic details on how to update it. If and when someone does so, a few things we might do:
- Consider another SQL doc tool. E.g. SchemaSpy can generate a diagram of a schema, but also an entire web site for the schema that we can place on https://doc.wikimedia.org
- Maybe link directly to the SVG file in Manual:Database_layout/viewbox, Firefox and Chrome seem to render the SVG better than the 2500-pixel png of the diagram
- Make the SVG text searchable. (Maybe it's drawing the font outlines). For such a large file, search is pretty important.
- Generate as a PDF as well.
- Store the .mwb file in core's docs directory in git instead of an external repo.