I think the issue reported in this post is still unsolved.
When you use system.db.runPrepUpdate() with numeric parameters might get an error like this:
This is happening to me with a MS SL Server 2008 R2 database, and not only with BigInts, but with any numeric type.
I think that, if this issue cannot be solved it would be great to add the workaround suggested in that post (casting to int) in the .runPrepUpdate() and .runPrepQuery() documentation, perhaps as a “known issue”. That can save lots of hours of frustration.
Ignition comes with painfully old JDBC drivers, for backward compatibility presumably. Replace the driver with the newest for your DB and many problems go away. Problems with round trips from java.lang.Long to jython long and back to java.lang.Long are a known problem in many older drivers.