--- In firebird-support@yahoogroups.com, "robert_hollay" <rhollay@...>
wrote:

>
> Hi,
>
> I have one dilemma.
> One of my clients has an old VB application which uses FB1.0 with
> an XTG ODBC driver. The VB app is closed source, I can't get the
> sources.
> Now, I have to make some (not too simple) reports from that
> database. I must write several select stored procedures to solve
> the problem.
> It would be much better for me if the database was FB1.5, because it
> has some very useful functions (CASE, COALESCE, etc.).
> My question is: is it safe to upgrade their FB1.0 server to FB1.5?
> Are there any issues that could cause the VB app not to function
> properly after upgrading the server?
> Is the backward compatibility 100% ?

Rephrasing the question, Is it safe to run FB 1.0? Well there are a
lot of known bugs resolved by 1.5 (check the 1.5 release notes), so
there are some very good reasons to choose 1.5 over 1.0.

The only problem you may find is relating to ambiguous queries. Take
this pretty simple query:

select id
from t1
join t2 on (t1.id = t2.t1id)

Firebird 1 would run the query and return data, but you could not know
whether the id field returned came from t1 or t2. Worse still, the
simple act of updating statistics on a particular index may change the
join order of the plan, and consequently the reports that were working
yesterday stopped working today for no apparent reason.

Firebird 1.5 or newer would not run that query. It would complain that
the id field is ambiguous to force you to specify what you actually meant.

So no-one can guarantee you wont encounter such issues, but then you
can't guarantee that you are not getting wrong data under 1.0 if you
do encounter those issues on Firebird 1.5

Adam