BUG: Batch executions silently accept SELECT statements

[jorsol]

Working on #935, I have just found a bug in batch execution, the driver silently accept SELECT statements in executeBatch(), but the specification clearly reads:

The method executeBatch throws a BatchUpdateException if any of the commands in
the batch fail to execute properly or if a command attempts to return a result set.

The JavaDoc for executeBatch:

Throws BatchUpdateException (a subclass of SQLException) if one of the commands sent to the database fails to execute properly or attempts to return a result set.

And the Java Tutorials:

You should not add a query (a SELECT statement) to a batch of SQL commands because the method executeBatch, which returns an array of update counts, expects an update count from each SQL statement that executes successfully. This means that only commands that return an update count (commands such as INSERT INTO, UPDATE, DELETE) or that return 0 (such as CREATE TABLE, DROP TABLE, ALTER TABLE) can be successfully executed as a batch with the executeBatch method.

The bug was introduced in #503, while it should not be a big deal, the specification is very clear about this, and must be corrected.

[vlsi]

Do you mean this change?
https://github.com/pgjdbc/pgjdbc/pull/503/files#diff-90f32da311526dc658f812dba0399924R54

Feel free to submit a PR that reverts that line -- we'll se which tests would be affected.

PS. The documentation is weird since "statements in 'return generated keys' mode are allowed to return results".

[jorsol]

Yes, that should do the trick...

[davecramer]

seems like this doesn't have any traction. @jorsol let me know if you think it should be reopened