Reflection Refresh Policies details

1

Could someone , please, explain some details about the Reflection Refresh policies ?
For ex.:
Full update
Unchecked the both checkbox
Refresh every 1h
Expire after 3h
What does happen here?

  1. every hour is made the full source data snapshot(reflection parquet format data).
  2. at third hour was expired last snapshot(dremio parquet data was cleaned), reflection was unavailable for dremio consumers(depend of the opened client session, of course)…
    Now, will run next, fourth refreshing?
    If new refresh will run - so, will restart the new cycle for the Expire, no?
    Does Expired event trigger once and definitely died?
    Sorry , it’s not so clear the design of Expire policy - to clean parquet reflection data once? What will happen for next, hourly, refresh event?
    thanks for some details.
2

@alex23ua If you refresh every one hour then after 3 hours only materialization > 3h will expire so your current reflection should be valid