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https://issues.apache.org/jira/browse/HUDI-5407?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Raymond Xu updated HUDI-5407:
-----------------------------
Sprint: 0.13.0 Final Sprint, 0.13.0 Final Sprint 2, 0.13.0 Final Sprint 3
(was: 0.13.0 Final Sprint, 0.13.0 Final Sprint 2)
> Rollbacks in MDT is not effective
> ---------------------------------
>
> Key: HUDI-5407
> URL: https://issues.apache.org/jira/browse/HUDI-5407
> Project: Apache Hudi
> Issue Type: Bug
> Components: metadata
> Reporter: sivabalan narayanan
> Assignee: sivabalan narayanan
> Priority: Critical
> Labels: pull-request-available
> Fix For: 0.13.0
>
>
> On rare conditions, rollbacks in MDT is not effective. Apparenlty, we have
> set cleaning policy to be lazy. hence rollbacks happens only when cleaner
> kicks in and not when we start a new commit. Given MDT is a single writer
> table, rollback blocks are effective only when the commit to rollback is just
> prior to the rollback block.
>
> Scenarios where this could fail w/ inline compaction.
>
> {code:java}
> Data table timeline
> t1.dc t2.comp.req. |Crash t3.dc t2.comp.inflight t2.commit
> MDT timeline
> t1.dc. t2.comp.inflight |Crash t3.dc t4.rb(t2) t2.dc
> {code}
>
> The first attempt of t2 in MDT should be rolled back since it crashed
> mid-way. in other words, if there are any log blocks written by t2 in MDT, it
> should be deemed invalid.
>
> But what happens is, here is how the log blocks are laid out.
> log1(t1). log2(t2 first attempt) crash.... log3 (t3) log4(t4.rb rolling back
> t2) ... log5 (t2)
>
> So, when we read the log blocks via AbstractLogRecordReader, ideally we want
> to ignore log2. but when we encounter log4 for a rollback block, we only
> check the previous log block for matching commit to rollback. since it does
> not match w/ t2, we assume log4 is a duplicate rollback and hence still deem
> log2 as a valid log block.
> hence MDT could serve more data files which are not valid from a FS based
> listing standpoint.
>
> Impact:
> log blocks to be ignored are considered valid if not for this fix.
>
>
>
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