David Mollitor created HIVE-24450:
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Summary: DbNotificationListener Request Notification IDs in Batches
Key: HIVE-24450
URL: https://issues.apache.org/jira/browse/HIVE-24450
Project: Hive
Issue Type: Improvement
Reporter: David Mollitor
Assignee: David Mollitor
Every time a new notification event is logged into the database, the sequence
number for the ID of the even is incremented by one. It is very standard in
database design to instead request a block of IDs for each fetch from the
database. The sequence numbers are then handed out locally until the block of
IDs is exhausted. This allows for fewer database round-trips and transactions,
at the expense of perhaps burning a few IDs.
Burning of IDs happens when the server is restarted in the middle of a block of
sequence IDs. That is, if the HMS requests a block of 10 ids, and only three
have been assigned, after the restart, the HMS will request another block of
10, burning (wasting) 7 IDs. As long as the blocks are not too small, and
restarts are infrequent, then few IDs are lost.
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