Any warnings/errors from MySQL? I see you don't check return values or check for errors. I always wrap my database actions in an eval block, and set RaiseError to 1 and AutoCommit to 0, with a commit at the end (and a roll back if the eval fails).

I also note that for each row returned from Oracle you start a new MySQL connection. While this has nothing to do with your problem, it's quite costly (setting up a database connection is relatively expensive) if Oracle returns many rows.