On Fri, 10 Apr 1998, Kent S. Gordon wrote:
[snip]
> > The first is, that when we update the OID which points to the
> > large object, the large object is orphaned. I realize that at
> > the time of the update, we could select the old OID and
> > subsequently drop the large object. The problem is that general
> > purpose tools such as MS Access do not provide an clean
> > framework for invoking such a query. Specifically, UPDATE
> > statements would have to be torn apart to build such a SELECT
> > statement. In the short term I can build a separate daemon to
> > track down the orphans. I hope VACUUM will eventually handle
> > these.
>
> You should be able to use triggers to fix the problem at the time that
> the update statement is run.
Yes that is one possibility, which I have done here, but this is a
generic problem, rather than one unique to a single application.
For triggers to work, you would have to add the trigger to each table, and
to each column that may contain a large object. Also, triggers are not
inherited.
Creating a new lo/blob data type would make this transparent to the user,
and would permit already written JDBC or ODBC based applications for other
databases to work without modification.
--
Peter T Mount petermount@earthling.net or pmount@maidast.demon.co.uk
Main Homepage: http://www.demon.co.uk/finder
Work Homepage: http://www.maidstone.gov.uk Work EMail: peter@maidstone.gov.uk
