Because WT prevents us from dropping a table until it has been checkpointed, if I have a query that spills and completes within the span of a single checkpoint, currently we must checkpoint everything in the table just to delete it, which is a waste of work.

The WiredTiger fast-truncate can remove the contents of a table very efficiently without performing unnecessary page reads. Before queueing the table for being dropped, we truncate the contents of the table, we avoid creating extra work for the next checkpoint.