Facilitating Garbage Collection
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By default, InterBase databases have a built-in function to automatically sweep old record versions when they become too numerous. However, sweeping is partially inhibited by outstanding active transactions. If the server cannot do complete garbage collection, it has to do extra work to maintain each client’s snapshot of the database.
Design your client applications to explicitly start and COMMIT transactions promptly, to reduce the number of outstanding transactions.
See Overview of Sweeping for more details on sweeping, garbage collection, and the database snapshot.