Critical Description
OAK-1292 introduced the following interesting but not very nice behavior:
On an idle system with no changes for an extended amount of time, the OAK-1292 change blocks the async indexer from updating the reference to the last indexed checkpoint. After one hour (the default checkpoint lifetime), the referenced checkpoint will expire, and the indexer will fall back to full reindexing.
The result of this behavior is that once every hour, the size of an idle instance will grow with dozens or hundreds of megabytes of new index data generated by reindexing. Older index data becomes garbage, but the compaction code from OAK-1804 is needed to make it collectable. A better solution would be to prevent the reindexing from happening in the first place.