There are times when it would be nice to know how many free pages are
available in a database. For example:

Suppose you have an application that stores large amounts of data in
Blobs. It is important to be able to monitor the database to know
when it is getting full. Initially this can be done by monitoring the
amount of free space on the drive(s) holding the database, but after
purging stale data this will no longer work since the database does
not shrink when the Blobs are deleted. In this case it would be nice
to be able to get the number of free pages in the database. I'm
thinking that this could be added as an option to the
isc_database_info API call.

I have some code that provides the same function by reading the
database directly and reporting on the number of free pages that way
but I am afraid some future change to the ODS will break this code. I
can contribute the code that I have if this will help.