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HBase >> mail # user >> reading WAL log file from inside coprocessor


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Jan Van Besien 2012-10-29, 09:42
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lars hofhansl 2012-10-29, 15:34
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Re: reading WAL log file from inside coprocessor
On 10/29/2012 04:34 PM, lars hofhansl wrote:
> I filed HBASE-4844 a while ago but never actually provided a patch.
> If you can comment on that jira with the exact use case that'd be helpful.
>
> If you wanted to work on a patch that'd be cooler even :)

Interesting thanks, I'll look into it.

The ticket seems to confirm that registering a WALActionListener from
inside a coprocessor is not going to work. Something I discovered today
as well.

With a completely different approach, I did manage to get something
working by constructing the path to the HLog files myself (in the
coprocessor) and reading them from there. So I am not notified about the
HLog files being rolled etc, I simply poll the directory on HDFS for
available files. It's a bit an ugly solution, and (apart from additional
delays) maybe there are even issues with it that I did not think of yet?

Anyway, I would like the HBASE-4844 approach a lot better for sure.

thanks,
Jan