I tried modifying the example I found on https://github.com/onefoursix/Cloudera-Impala-JDBC-Example in order to do inserts.
Using library version 0.10.0-cdh4.5.0.
I created a sample table with impala-shell.
create table example_table
Querying this table with the original JDBC example works fine.
However, when I run an insert statement (that works fine in the shell), it fails with no error: nothing gets written in the tables.