Subject Proxy Query ?
Is it possible to write UDF (exetended stored proc) that opens
another database, runs query across that database and return the
result back to IB ? Is there problem by accessing IB back-end engine
again from UDF ? It will be ideal to return cursor or complete result
set !

For example sybase support proxy table that is similar to this idea,
and MsSql does not have problems to access more databases at all.