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Posted to issues@hbase.apache.org by "stack (JIRA)" <ji...@apache.org> on 2013/08/11 07:45:49 UTC
[jira] [Updated] (HBASE-8741) Scope sequenceid to the region rather
than regionserver (WAS: Mutations on Regions in recovery mode might have
same sequenceIDs)
[ https://issues.apache.org/jira/browse/HBASE-8741?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
stack updated HBASE-8741:
-------------------------
Summary: Scope sequenceid to the region rather than regionserver (WAS: Mutations on Regions in recovery mode might have same sequenceIDs) (was: Mutations on Regions in recovery mode might have same sequenceIDs)
> Scope sequenceid to the region rather than regionserver (WAS: Mutations on Regions in recovery mode might have same sequenceIDs)
> --------------------------------------------------------------------------------------------------------------------------------
>
> Key: HBASE-8741
> URL: https://issues.apache.org/jira/browse/HBASE-8741
> Project: HBase
> Issue Type: Bug
> Components: MTTR
> Affects Versions: 0.95.1
> Reporter: Himanshu Vashishtha
> Assignee: Himanshu Vashishtha
> Fix For: 0.95.2
>
> Attachments: HBASE-8741-v0.patch, HBASE-8741-v2.patch, HBASE-8741-v3.patch, HBASE-8741-v4-again.patch, HBASE-8741-v4-again.patch, HBASE-8741-v4.patch, HBASE-8741-v5-again.patch, HBASE-8741-v5.patch
>
>
> Currently, when opening a region, we find the maximum sequence ID from all its HFiles and then set the LogSequenceId of the log (in case the later is at a small value). This works good in recovered.edits case as we are not writing to the region until we have replayed all of its previous edits.
> With distributed log replay, if we want to enable writes while a region is under recovery, we need to make sure that the logSequenceId > maximum logSequenceId of the old regionserver. Otherwise, we might have a situation where new edits have same (or smaller) sequenceIds.
> We can store region level information in the WALTrailer, than this scenario could be avoided by:
> a) reading the trailer of the "last completed" file, i.e., last wal file which has a trailer and,
> b) completely reading the last wal file (this file would not have the trailer, so it needs to be read completely).
> In future, if we switch to multi wal file, we could read the trailer for all completed WAL files, and reading the remaining incomplete files.
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