losing my large objects with Postgresql 8.1.4 and 8.1.5

Some of my custom server functions/data types that work correctly
under Postgresql 8.0.1 are having trouble with lost large objects
under Postgresql 8.1.4 and Postgresql 8.1.5, but only in particular
usages. I'm hoping somebody familiar with the changes made to
Postgresql since 8.0.X can suggest what might be happening.

Details:
I have a datatype for storing large blocks of data. Because a block
of data may be multi gigabytes in size, I can't rely on the toaster
mechanism. Instead, each instance of my datatype contains a key to
another table that contains a list of oids for large objects (each
containing a portion of the block).

My functions are written in C using the SPI interface. One of the
functions creates an instance of the datatype, and another one
converts the datatype to text.

When I execute the following sequence of commands:
select MyTypeToText( BuildMyType('asdf'));
I get the following error
ERROR: large object 33016 does not exist
\lo_list (in psql) doesn't show any new large objects.

However, when I execute the following sequence of commands:
create table smith( a MyType);
insert into smith select BuildMyType('asdf');
select MyTypeToText(a) from smith;
the contents of the MyType object are displayed correctly, no error messages.
\lo_list shows an additional large object.

I have stepped through both the BuildMyType function and the
MyTypeToText function and seen that the
lob id that BuildMyType is using is the same one that MyTypeToText is
trying to use in the problem case.

I tried producing a reduced version of the MyType code to demonstrate
the problem but unfortunately it works perfectly.

Can anybody suggest what could cause this type of behavior?

Thank you,

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Eric Davies, M.Sc.
Barrodale Computing Services Ltd.
Tel: (250) 472-4372 Fax: (250) 472-4373
Web: http://www.barrodale.com
Email: eric(at)barrodale(dot)com
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