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https://issues.apache.org/jira/browse/HBASE-4844?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13164022#comment-13164022
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Lars Hofhansl commented on HBASE-4844:
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bq. The logroller could signal new log to copy?
Right, and it could trigger a coprocessor hook to do the actual work of
archiving. The coprocessor would get the path to the old file and then copy it
somewhere else.
Looking at the code, there're races, though. Until the HLogs.writer is set to
the new writer, all writes would still go to the old file. So if the
coprocessor post hook is before that and it makes a copy of the file some edit
might be missed (that go into the old file after it was copied, but before the
writer was switched over).
Wouldn't it be nice if we had hardlinks in HDFS? :)
So I think the coprocessor post hook should be called after the HLog.writer
assignment. If it did the copy synchronously it only needs to finish before the
next log for the same regionserver is rolled (still a race, though).
I'll attach a very simple patch tonight or tomorrow morning and then folks can
poke holes in it.
> Coprocessor hooks for log rolling
> ---------------------------------
>
> Key: HBASE-4844
> URL: https://issues.apache.org/jira/browse/HBASE-4844
> Project: HBase
> Issue Type: New Feature
> Affects Versions: 0.94.0
> Reporter: Lars Hofhansl
> Priority: Minor
>
> In order to eventually do point in time recovery we need a way to reliably
> back up the logs. Rather than adding some hard coded changes, we can provide
> coprocessor hooks and folks can implement their own policies.
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