On 10-11-2020 21:26, Joaquin Oltra Hernandez wrote:
TLDR: Wiki Replicas' architecture is being
redesigned for stability
and performance. Cross database JOINs will not be available and a host
connection will only allow querying its associated DB. See 
for more details.
If you only think of Wikipedia, not a lot will break probably, but if
you take into account Commons and Wikidata a lot will break. A quick
grep in my folder with Commons queries returns 123 lines with cross
database joins. So yes, stuff will break and tools will be abandoned.
This follows the practice that seems to have become standard for the WMF
these days: Decisions are made with a small group within the WMF without
any community involved. Only after the decision has been made, it's
Unhappy and disappointed,