Strange issue with JDBC add Postgres

I'm encountering a strange problem with using the JDBC component with
Postgresql.
Postgresql by default fetches large result sets into memory. To avoid
this you need to use
statement.setFetchSize()
to make it use a cursor.
This works fine in a simple Java example. But when I try to use it in
Camel I get a strange exception thrown from deep down in Postgresql.
My route looks a bit like this:

from('direct:databasequery')
.to('jdbc:myDataSoruce?outputType=StreamList닖굺枧.fetchSize=100')
.split(body()).streaming()
.log('Processing row')

I then send it a body containing something like:
select * from a_very_large_table

When I combine it with maxRowSize=10 its fine.
When I combine it with maxRowSize=1000 it blows up, so it looks like it
fails when it needs to go back for a second chunk of data.
The error from Postgresql is this:

Caused by: org.postgresql.util.PSQLException: ERROR: portal "C_2" does
not exist
at
org.postgresql.core.v3.QueryExecutorImpl.receiveErrorResponse(QueryExecutorImpl.java:2198)
at
org.postgresql.core.v3.QueryExecutorImpl.processResults(QueryExecutorImpl.java:1927)
at
org.postgresql.core.v3.QueryExecutorImpl.fetch(QueryExecutorImpl.java:2130)
at
org.postgresql.jdbc2.AbstractJdbc2ResultSet.next(AbstractJdbc2ResultSet.java:1917)
at
org.apache.camel.component.jdbc.ResultSetIterator.loadNext(ResultSetIterator.java:117)
at
org.apache.camel.component.jdbc.ResultSetIterator.next(ResultSetIterator.java:83)

Anyone got any idea what's going on here?

Tim