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https://issues.apache.org/jira/browse/ASTERIXDB-2444?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16612507#comment-16612507
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ASF subversion and git services commented on ASTERIXDB-2444:
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Commit 5550a5f225a0528fe2229d2b39db4595590ab0ea in asterixdb's branch
refs/heads/master from [~mhubail]
[ https://git-wip-us.apache.org/repos/asf?p=asterixdb.git;h=5550a5f ]
[ASTERIXDB-2444][STO] Avoid Using System Clock in Checkpoints
- user model changes: no
- storage format changes: yes
- interface changes: yes
Details:
- Replace the usage of system clock timestamps in checkpoints
by a sequencer.
- Update Asterix/Hyracks storage version to reflect the recent
changes in storage.
- This change is expected to break storage backward compatibility.
Change-Id: Idc061e6eaccfb308b29a5a263b77a0a849694d4f
Reviewed-on: https://asterix-gerrit.ics.uci.edu/2961
Reviewed-by: Michael Blow <[email protected]>
Integration-Tests: Michael Blow <[email protected]>
Tested-by: Michael Blow <[email protected]>
> Potential data loss due to clock drift
> --------------------------------------
>
> Key: ASTERIXDB-2444
> URL: https://issues.apache.org/jira/browse/ASTERIXDB-2444
> Project: Apache AsterixDB
> Issue Type: Bug
> Components: STO - Storage
> Affects Versions: 0.9.4
> Reporter: Murtadha Hubail
> Assignee: Murtadha Hubail
> Priority: Major
> Fix For: 0.9.5
>
>
> Currently we use a timestamp based on the current system time to sort the
> index files to identify the order in which the index components should be
> searched. If the system clock is changed to a time earlier than the latest
> index component time and a new component written, it will result in sorting
> the components in a wrong order. This issue can also be encountered if a
> current master replica has a system time that is ahead of another replica. If
> the current master fails and that replica is promoted, it might generate new
> components with an earlier timestamp. The same issue is applicable in
> component ids.
> Proposed Fix:
> Avoid using the system clock timestamp and use a simple monotonically
> increasing sequencer.
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