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https://issues.apache.org/jira/browse/HIVE-24450?focusedWorklogId=518138&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-518138
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ASF GitHub Bot logged work on HIVE-24450:
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Author: ASF GitHub Bot
Created on: 30/Nov/20 21:53
Start Date: 30/Nov/20 21:53
Worklog Time Spent: 10m
Work Description: pvargacl commented on pull request #1718:
URL: https://github.com/apache/hive/pull/1718#issuecomment-736078852
@belugabehr Although I am not very familiar with this area, but what happens
if multiple HMS are running in HA? Wouldn't this solution mean, that
potentially the order of the notification events will change? Two HMS are
running HMS 1 gets id range 1-10, HMS 2 gets 11-20. Then openTxn notification
goes to HMS 2 and allocateWriteId notification goes to HMS1. The sequence of
the ids will not represent the sequence of the events. Wouldn't this mess up
acid table replication?
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Issue Time Tracking
-------------------
Worklog Id: (was: 518138)
Time Spent: 20m (was: 10m)
> 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
> Priority: Major
> Labels: pull-request-available
> Time Spent: 20m
> Remaining Estimate: 0h
>
> 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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