Health check for search indexes

[melslenstra-dc]

The search indexing engine, Lucene/Examine, has shown to be quite prone to failure in such a way that it does not automatically recover itself. We've seen many cases where a corrupt index simply results in the index returning 0 items incorrectly.

It would be great if Umbraco would monitor the correct functioning of its indexes by adding a Health Check that, for example, determines periodically if items are returned by the index in a correct fashion (e.g. by querying directly against the database and comparing the result with an index query's results).