The primary key is usually a bigint column, but the foreign key columns
are usually of integer type. This can lead to issues when joining these
columns due to mismatched types and different value ranges.
This commit updates the plugin to the latest guidelines, as shown in
discourse-plugin-skeleton, which involves moving a lot of the code to
dedicated files, use proper namespaces, use the autoloader as much as
possible, etc.
Reintroduces the migration removed in `cdfc5d4`, and fixes it to work with `query_groups`. Since the code is fairly complex, I moved into a rake task so it can be tested and make sure it works.
Bianca Nenciu
David Taylor
Roman Rizzi
Daniel Waterworth
Krzysztof Kotlarek