How to communicate limitations of search when a Solr re-index is running?
When a Solr re-index is running (see sshoc-marketplace-backend#148 (closed) for further informations) the search will deliver no or only partly results. This would be not so much a problem if this would be a matter of seconds/minutes but we discovered yesterday that for the currently 5200+ items it takes around 4 hours to finish such a re-index. Besides the question why this takes so long, we need to think about a way how to communicate on the MP such a situation when during many hours search results are incomplete. And in general we should also think about situations where we need to shut down MP due to maintenance work.
One way could be to have an option for administrators to put the MP into maintenance mode thus showing to visitors of the MP an information message, that either the MP is not available currently or that the MP delivers insufficient results. Additionaly, it could be necessary to allow to change the information text that is delivered to visitors based on the cause of the maintenance.
For the Solr re-index it is not always clear when it is initiated e.g. what happens if servers re-start. Thus putting the MP in maintenance mode manually could be forgotten/not possible. In such cases we could think about an mechanism where the maintenance mode is changed automatically by backend, e.g. if re-index is started then put MP in maintenance and after finishing re-index put it back online.
What are your opinions @matej.durco @tparkola @ekalata @lbarbot @alex @stefan.probst @edward.gray @anowak - anyone else interested in the discussion?