Purging of features and observations that have been marked as deleted runs as a background tasks on the Redbex Application Server. Whenever a feature or observation is deleted the task of purging that feature or observation (i.e. deleting data from the Redbex Application Server Database) is put onto a purge-queue.

A purging background process will monitor the purge-queue and will actually delete the features or observations on that queue one by one. If big amounts of features and observations are marked as deleted in a short period of time the purge-queue will grow since the process of purging might take longer than the marking features or observations as deleted. I.e. the time it takes for a feature or observation to be actually removed from the Redbex Application Server Database varies according to the size of the purge-queue the overall system load etc.

The Application Server also implements a prioritization on the purge queue i.e. it is not guaranteed that the first deleted feature or observation is also the first to be purged.

The purging process runs as a single thread i.e. purging of elements on the queue is done sequentially.

When the Application Server starts up it will check for all features and observations marked as deleted and will initially fill the purge queue. Therefore after an ungraceful shutdown of the Application Server content purging will resume immediately when starting the Application Server again.

Monitoring the purging process

The process handling the purge-queue and actually deleting data from the Redbex Application Server Database updates the performance counters Content purging queue size and Content purging average time.