To update what you've said with insider info, ad-hoc SQL performance is currently a big focus at VoltDB. We fully support ad-hoc access in auto-commit mode through our native clients or through JDBC. Currently, we can do hundreds or thousands of statements/sec, and we expect performance to increase dramatically in the next few months.

Here's the Epic in JIRA: https://issues.voltdb.com/secure/IssueNavigator.jspa?reset=t...

Typically, applications are not 100% ad-hoc on VoltDB, but we're starting to see more hybrid use cases. Stored procedures can be used for extreme throughput or for transactional requirements, but other parts of the app can be more flexible.