Firebird Database Keeps getting larger

Question

This one is interesting to me - despite the almost inane title. I have used Firebird for a long time, but not until recently noticed an interesting behavior.

I am using embedded firebird 1.5, and noticed that if I stuff the database full of blobs (lets say 10mb worth), the size of the database increases. I can then delete all the fields in the database, and the file size of the DB remains at its expanded size. Currently it is at 20mb and is completely empty.

I know that firebird has this built into its architecture (for quick indexing, speed issues etc), but I always thought it would decrease back down to its original ~2mb default.

Does anyone have any suggestions to 'deflate' the file size? The reason being is that this is a space conscious issue. If I had tons of space to work with, I wouldn't care. However that is not the case, and I need things to be as optimal as possible

Thanks!

Answer 1

The only way to free unused space in a firebird database is to do a backup then an immediate restore of that backup (Reference: Firebird FAQ).

Here is a good technical explanation of why this is so.

Note that Firebird will reuse the currently unused space - ie. if you put another 10MB of blobs in now, the database should not grow to 30MB.