Possible memory leak with SQL function?

Hello list,

Is the following known behaviour, or should I put some time in writing a
self contained test case?

We have a function that takes a value and returns a ROW type. With the
function implemented in language SQL, when executing this function in a
large transaction, memory usage of the backend process increases.
MemoryContextStats showed a lot of SQL function data. Debugging
init_sql_fcache() showed that it was for the same function oid each
time, and the oid was the function from value to ROW type.

When the function is implemented in PL/pgSQL, the memory usage was much
less.

I'm sorry I cannot be more specific at the moment, such as what is 'much
less' memory with a PL/pgSQl function, and are there as many SQL
function data's as calls to the SQL function, because I would have to
write a test case for this. I was just wondering, if this is known
behavior of SQL functions vs PL/pgSQL functions, or could it be a bug?

--
Yeb Havinga
http://www.mgrid.net/
Mastering Medical Data