Hi,

>Does anybody knows what can this be? Is this an internal maintenance?

To me that sounds to be garbage collect or automatic sweep.

> If yes, how can schedule it to do it in specific time range?

You can turn automatic sweep OFF using:

gfix -housekeeping 0 your_database

than, you can run manual sweep from time to time (eg. on a daily basis,
every night -- that dependes on each case)

gfix -sweep your_database

> Something else, what kind of maintenance we must do on firebird database
> files?
> How often?

That depends on your applications/use. AFAIK, If you keep transactions short
so that cooperative GC is running efectively, than you'll have less need for
maintainance (sweep) -- Good transaction handling is the key for a healthy
DB.

Also, from time to time (let's say 6-12 months) may be a good idea to backup
and restore your database, getting rid of any fragmentation.


Regards,
Anderson Farias