>> Do we need to backup on 2.5.1 and restore to 2.5.2?
>
>> In this particular case, you do need backup/restore.
>
>> Dmitry
>
> __._,_._
>
> I´m curious Dmitry, why?

From the 2.5.2 RC1 release notes.

Warning re Databases Created or Restored under Firebird 2.5.1
All users upgrading from Firebird 2.5.1 to a higher sub-release are
strongly advised to migrate databases using
gbak backup/restore. If this is impracticable, at least rebuild all
compound indices in the databases being
migrated.
Databases being upgraded from older Firebird versions (ODS 11.1 and
lower) or v.2.5.0 are not affected by
this regression.

--
With regards,
Thomas Steinmaurer
http://www.upscene.com/