Why doesn't the database file shrink when I delete records?

Many users wonder why they don't get their disk space back when they delete a lot of records from database.

The reason is that it is an expensive operation, it would require a lot of disk writes and memory - just like doing refragmentation of hard disk partition. The parts of database (pages) that were used by such data are marked as empty and Firebird will reuse them next time it needs to write new data.

If disk space is critical for you, you can get the space back by doing backup and then restore. Since you're doing the backup to restore right away, it's wise to use the "inhibit garbage collection" or "don't use garbage collection" switch (-G in gbak), which will make backup go A LOT FASTER. Garbage collection is used to clean up your database, and as it is a maintenance task, it's often done together with backup (as backup has to go throught entire database anyway). However, you're soon going to ditch that database file, and there's no need to clean it up.

Do you find this FAQ incorrect or incomplete? Please e-mail us what needs to be changed. To ensure quality, each change is checked by our editors (and often tested on live Firebird databases), before it enters the main FAQ database. If you desire so, the changes will be credited to your name. To learn more, visit our add content page.

All contents are copyright © 2007-2024 FirebirdFAQ.org unless otherwise stated in the text.

Links   Firebird   News   FlameRobin   Powered by FB: Home Inventory   Euchre  
Add content   About  

 Installation and setup
 Backup and restore
 Connectivity and API
 Errors and error codes