Invoking a function within a batch statement

Hello,

I'm having trouble invoking a PostgreSQL function
<https://www.postgresql.org/docs/9.4/static/sql-syntax-calling-funcs.html>
within a prepared batch statement, and I'm wondering if it's possible that
I'm encountering a limitation in the JDBC driver.

For context, my application uses jDBI v2.63.1 with version 9.4-1204-jdbc42
of the Postgres driver. I've implemented a feature which requires insertion
into certain tables using a custom PL/pgSQL function. In order to issue
batches of these queries within a single transaction, I'd like to use
jDBI's `(at)SqlBatch` annotation. However, because Postgres functions are
invoked using SELECT, they return a table-like result, so even though my
PL/pgSQL function returns VOID, the queries fail in the JDBC driver because
it's expecting a null result.

The jDBI-annotated DAO method in question:

@SqlBatch(
transactional=true,
value="SELECT append_to_time_series(<arguments_redacted>)")
public void insertV2(
...
);

This results in a BatchUpdateException wrapping a PSQLException which
indicates a root cause of an unexpected null result: https://gist.github.
com/evnm/17a370c6ead2a2dfeaab0285e067897a

This issue is being tracked in a jDBI issue on GitHub
<https://github.com/jdbi/jdbi/issues/447>, which links to some relevant
discussion that took place on the jDBI mailing list. Any insight from the
JDBC community would be greatly appreciated.

--
Evan Meagher