Subject RE: [firebird-support] Re: Firebird and vacuum?
Author Helen Borrie
At 12:16 AM 7/11/2007, you wrote:
>Am I correct in understanding that the garbage collection is only effected,
>once a restore is performed, after the backup?

No. By default, garbage collection always occurs during gbak -b, since it reads every record in every table. If you plan to restore the database afterwards, you don't need the overhead of GC so you can "switch it off" with the "-g" switch.

Backups never contain garbage, but this isn't because of GC. It's because of what a backup is - it's metadata and data stored apart. "Data" means the latest committed version of each record in a compressed format that gbak -r or gbak -c unravels and loads into brand-new structures and brand-new pages. Page images are not stored at all.