data collector retention
I'm seeing some odd or possibly undocumented behavior from the data collector retention policy.
We have our policy set at 50,000kb with no time limit on RequestsIssued, RequestsCompleted, Errors, and ResourceAcquisitions to set the overall retention for v_monitor.query_requests.
I'm doing some analysis over the last few monthsand have data for all users over that time period except for 1. That user is a service account that issues far more queries than any of the others. The history for that user only has data for the last few weeks.
Sometime in the past one of our admins had set up a dump of query_requests to another table at regular intervals, maybe because the data collector had been seen as unreliable in the past, but I couldn't confirm the reason. Anyway, I have at least some of the historical data I need for that user because of that mechanism.
Is there some sort of undocumented selection process for purging data collector data? Maybe the system is purging data at the user level when the max size is reached? I would think that the oldest data would roll off regardless of any criteria but that doeasn't seem to be what I'm experiencing.