We are creating a virtual scolling list that will contain 100,000+
entries, however only 20-100 entries will be displayed at any given
time to the user. Each entry corresponds to a row in the database,
and has multiple fields, which the user can sort the entries on.
Because there are multiple users, the table will have millions of
rows. There will be multiple users running on the same machine
concurrently, so I would like to avoid loading all the entries in the
list into memory.

In order to support basic scrollbar functionality, I need to be able
to grab windowed chunks of 20-100 out of sorted list. On SQL Server,
they have bi-directional cursors where I can randomly access the data.
I haven't been able to find anything like this on Firebird. Any
ideas as to how I would do this using Firebird?
Virtual scrolling requirements:

1. return the total number of records(rows) in a query result set.
2. Be able to efficiently return a window of result set rows based on
a offset into the result set and a count of records.
3. Be able to sub query the result set mentioned above to retrieve the
index of a particular row.

As far as I understand Firebird doesn't have bi-directional cursors.
I understand that firebird may not have the exact functionality I
described above.

I was wondering if there was another way to get that functionality or
work around missing features in firebird?

Thanks

-Joey