New event store and prefiltering by default

12.6 introduces the use of the new event store and pre-filtering of events by default.

Events are now stored in a Solr core (they are also still stored in the old database store for now as a retro compatibility measure).

User notifications are now associated to each user when they are generated and not when they are requested. This means that gathering is always fast and that the filtering of events is using the preference of the user at the moment the event was generated so modifying your preference will only affect new events. The pre-filtering processing is also asynchronous and done in a low priority thread to not impact the farm so there might be a delay between the action and the appearance of the related notification in the notification list in a very active wiki with a lot of users.

Even if it was implemented along the course of 12.x it's still the first time that this is enabled for most users so don't hesitate to report any notification related issue to https://jira.xwiki.org/projects/XWIKI. If you hit a blocker bug you can go back to:

• post filtering of event using the property notifications.eventPrefilteringEnabled in xwiki.properties
• use only the database store by disabling the new one using the property eventstream.store.enabled in xwiki.properties