Garbage Collection (Overview of Sweeping)

From InterBase

To limit the growth of the database, InterBase performs garbage collection by sweeping the database. This process frees up space allocated to outdated record versions. Whenever a transaction accesses a record, outdated versions of that record are collected. Records that were rolled back are not collected. To guarantee that all outdated records are collected, including those that were rolled back, InterBase periodically sweeps the database.