How much logging should I do at production for SQLExcpetions?

Question

I'm writing a small database-centric application in Java Swing that will be used internally in a small company. I haven't much experience with developing production-level applications.

I don't use an ORM, just a few simple methods that run SQL queries with Java JDBC. On every method that access the database I use a try-catch statement for SQLException and IOException. Should I do any logging here? In case I should, how much should I log? Please give me examples of good practice in this case.

Answer 1

Two main things in production system are:

1. Don't blow up the logs with information that is not interesting
2. Allow raising the log level for troubleshooting purpose.

Use some kind of a logging infrastructure. If the exception can occur during the normal operation, report it in debug level. If it is a real problem, report it in error level. Either way you will have a way to troubleshoot the system by raising the log level.

Also - when you report an exception always make sure the the entire stack trace + inner exceptions are printed.

Answer 2

IMHO, here is the very minimum you should do. I assume you are using Log4J.

try
{
   // open connection

   // begin transaction

   // my database stuff

   // commit transaction
}
catch (SQLException ex)
{
   log.Error("An error occured while ...: " + ex.Message, ex);
   // do stuff related to SQLException

   // rollback transaction
}
catch (IOExcpetion ex)
{
   log.Error("An error occured while ...: " + ex.Message, ex);
   // do stuff related to IOException

   // rollback transaction
}
catch (Exception ex)
{
    log.Error("An error occured while ...: " + ex.Message, ex);
    // manage this unhandled exception

    // rollback transaction
}
finally
{
   // close connection
}