问题
I am trying to get started with Cassandra triggers, but I cannot get Cassandra to load them. I have built jar files from here and here, and put them under C:\Program Files\DataStax-DDC\apache-cassandra\conf\triggers. I have restarted the DataStax_DDC_Server service (on Windows) and reopened the CQLSH command line, but trying to use the trigger class in a create trigger command gives me only:
ConfigurationException: <ErrorMessage code=2300 [Query invalid because of configuration issue] message="Trigger class 'org.apache.cassandra.triggers.InvertedIndex' doesn't exist">
I checked the jar files, and they include the class files.
The only thing I could find in the log files of cassandra is Trigger directory doesn't exist, please create it and try again. But I don't know if that is relevant.
EDIT: Following the last line shown here, I edited the cassandra.bat file. Now if I stop the DataStax_DDC_Server service and run the bat file directly, the create trigger command succeeds. Nevertheless, the service seems to be independent of this bat file. The question now is how to apply the same config to the service?
回答1:
After googling creatively, I found a solution. As mentioned here you need to explicitly set the cassandra.triggers_dir variable, but for the service to pick it up, as explained here, you must configure it in the registry. So the answer is to update the registry key
HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Apache Software Foundation\Procrun 2.0\DataStax_CDC_Server\Parameters\Java\Options
and add the line
-Dcassandra.triggers_dir=C:\Program Files\DataStax-DDC\apache-cassandra\conf\triggers
Note that the path should not be enclosed in quotations, or it won't work. Don't forget to restart the service.
回答2:
Above solution is working for window. it's difficult in window to find registry option. so to find registry option go to start menu and type "regedit" it will open registry window then you can do above settings.
来源：https://stackoverflow.com/questions/37572209/cassandra-3-5-fails-to-load-trigger-class