Enrico,

> what kind of index we must add to our database, an Index on system
> tables ?
> But this kind of operation are not discouraged ?
> I don't remeber why but during the transition fron FireBird 1.0.x to
> 1.5.x i have readed that the index on the system table are lost in some
> circustances, backup -> restore or some other.

Firebird 1.5 introduced three new indexes on system tables, thus this
was one reason why the ODS (On-Disk Structure) was increased from 10.0
to 10.1.

These indexes will be created when moving from Firebird 1.0 to 1.5, when
you make a backup with 1.0 and a restore under 1.5. They shouldn't get
lost whenever you make a restore under Firebird 1.5.


--
HTH,
Thomas Steinmaurer
LogManager Series - Logging/Auditing Suites supporting
InterBase, Firebird, Advantage Database, MS SQL Server and
NexusDB V2 (NEW!)
Upscene Productions
http://www.upscene.com