Part of the effort is to enhance the results metrics.
This metrics should store the number of pipelineruns and taskruns which were not stored in the database before deletion.
Metrics should look like 
watcher_runs_not_stored_count{kind="PipelineRun",namespace="default"}

Initial work is done by Andrew here https://github.com/tektoncd/results/pull/1064.
Rest of the work includes testing the metrics, writing unit tests and updating the docs.