Version 1.6.6
Compaction

The WT_SESSION::compact method can be used to compact a row- or column-store btree (log-structured merge trees cannot be compacted).

The data source does not have to be quiescent, compaction may be performed on a live data source.

Because checkpoints named by the application are not discarded until explicitly removed or replaced, they may prevent WT_SESSION::compact from accomplishing anything.