Normally, when an error occurs in the Berkeley DB library, an errno value is returned by the function. In some cases, however, this value may be insufficient to completely describe the cause of the error, especially during initial application debugging.
There are four additional configuration options intended to provide applications with additional run-time error information. They are db_errcall, db_errfile, db_errpfx and db_verbose.
If these options are configured when the environment is first initialized by calling db_appinit, many Berkeley DB errors will result in additional information being written to a file or passed as an argument to an application function.
The Berkeley DB error reporting facility does not slow performance or significantly increase application size, and may be run during normal operation as well as during debugging. Where possible, we recommend that these options always be configured and the output saved in the filesystem. We have found that that this often saves time when debugging installation or other system integration problems.