Hi Denis!
Sorry for the late response.
The information is in the installation requirements, see https://www.mediawiki.org/wiki/Extension:Wikibase_Repository#Requirements.
Where did you expect to find it? Perhaps we can add it in some more places to avoid confusion and frustration. In the README file, maybe?
-- daniel
Am 06.03.2017 um 09:05 schrieb Denis Rykov:
Hello!
It looks like Wikibase extension is not compatible with PostgreSQL backend. There are many MySQL specific code in sql scripts (e.g. auto_increment, varbinary). How about to add this information to Wikibase docs? //