Daniel Dai created HIVE-21697:
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Summary: Remove periodical full refresh in HMS cache
Key: HIVE-21697
URL: https://issues.apache.org/jira/browse/HIVE-21697
Project: Hive
Issue Type: Improvement
Components: Standalone Metastore
Reporter: Daniel Dai
Assignee: Daniel Dai
In HIVE-18661, we added periodical notification based refresh in HMS cache. We
shall remove periodical full refresh to simplify the code as it will no longer
be used. In the mean time, we introduced mechanism to provide monotonic reads
through the CachedStore.commitTransaction. This will no longer be needed after
HIVE-21637. So I will remove related code as well. This will provide some
performance benefits include:
1. We don't have to slow down write to catch up notification logs. Write can be
done immediately and tag the cache with writeids
2. We can read from cache even if updateUsingNotificationEvents is running.
Read will compare the writeids of the cache so monotonic reads will be
guaranteed
I'd like to put a patch separately with HIVE-21637 so it can be tested
independently. HMW will use periodical notification based refresh to update
cache. And it will temporarily lift the monotonic reads guarantee until
HIVE-21637 checkin.
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