Downgrade 3 to 2.5 with gbak?

[Tim Crawford]

Is is possible, and  safe to downgrade a Firebird 3 database to 2.5 with
gbak?

Assuming no database object changes (same tables, column indexes etc)
but with new/modified row data only.

I am looking to have a contingency plan in case some catastrophic problem
comes up that requires application code changes which cannot be done
within a reasonable time frame.

Google search indicates some people have done this,.
I haven't bothered trying it yet, no point if I get a resounding NO for
an answer

Thanks
Tim

Notes:

A couple of existing databases have been upgraded to 3.0 from 2.5,
and no issues have been found with a first pass of  testing of the main
functionality.

However it is not reasonable to extensively test ever piece of code in
the application,
there are tens of thousands of lines of 20 year old Delphi 3 code,
probably have of
which doesn't actually even execute....

If I upgrade a customer database to version 3 and issues come up, it
will not
be possible to fix problems with application source code changes in a
timely manner

The existing databases were originally Firebird 1.5, though might have
started as Interbase.
Upgrading to 2.5 was done a few years ago without issues (there might
have been one or two
minor things, but that was years ago, and we had a developer who cold
fix the code pretty easily)
Databases are dialect 1 and have to remain that way for the foreseeable
future, so no Date or TIme columns,
of course no Booleans columns, no BIGINT etc.
Databases objects are 99% Tables, Columns and Indexes, a handful of
sequences
Columns almost entirely varchar and integers and timestamp, a couple of
float and a couple of blobs

[Dimitry Sibiryakov]

Tim Crawford wrote 16.04.2024 21:17:
> Is is possible, and  safe to downgrade a Firebird 3 database to 2.5 with gbak?
>
> Assuming no database object changes (same tables, column indexes etc)
> but with new/modified row data only.

*IF* the object weren't changed then just use gbak version 2.5 to create
backup from server version 3. And, naturally, you cannot use "-se" switch.

--
WBR, SD.

[Tim Crawford]

Thanks!

[Fabiano SCI]

In my opinion, based as someone that migrated the same way I suggest you to at least go direct to Firebird 4 (I dont have experience with FB 5) . With FB 4 you get few problems with record versions and the migration process is the basically the same to 3 or 4.