running data purge job from admin control page

John Sanda jsanda at redhat.com
Thu Nov 21 02:51:59 UTC 2013


Earlier today the question came up about whether or not if we can force the execution of the data purge job. You can if you enable debug mode in system settings and then go to http://localhost:7080/portal/admin/test/control.jsp. Due to implementation changes, executing the data purge job here will basically result in a no-op for metrics compression. 

I need to give a little background on the C* implementation to explain why this is so. When the metrics compression runs, we look at the current time, round down to the hour, and then subtract an hour to get the time slice for raw data to be aggregated. For example, suppose the data purge job is running during the 20:00 hour. The time slice over which we aggregate raw data will be 19:00 to 20:00. We use a custom index table to query for schedule ids that have data to be aggregated. The row keys are timestamps that correspond to the start of a particular time slice. The index gets updated whenever data is inserted. So for any raw data inserted during the 19:00 hour, the corresponding schedule id will have an entry in the 19:00 hour row. After the raw data for the schedules is aggregated, the row is deleted.

If I go to control.jsp at 20:25 and execute the data purge job, it will attempt to aggregate raw data for hour 19:00, not 20:00. And because the 19:00 hour row in the index is deleted, we will get an empty result set when querying for schedule ids with data to aggregate. If people utilize control.jsp to perform on demand aggregation, then we can look at making changes to continue supporting that behavior.

- John


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