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https://issues.apache.org/jira/browse/HBASE-4354?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13100910#comment-13100910
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stack commented on HBASE-4354:
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A long time ago we had a history column in .META. It tried to note each
transition a region went through. The history of a region was kept in its row
up in .META. It was a kinda nice feature. It was also a super pain at the
same time. We had lots of issues around regionservers trying to update history
in .META. though .META. was gone and we couldn't do full history; e.g. the
close of a region on a cluster shutdown. There may have been deadlocks too
around updating history while trying to do edits in .META. but my memory may
not be serving me right here. In the end we stripped the feature out because
it was more trouble that it was worth.
That said, I think this would be good to have. The natural place to do this
stuff would be in a table inside hbase I'd think. But then what to do if this
table is not online or if we are shutting down the cluster and you want to log
region close?
> track region history
> --------------------
>
> Key: HBASE-4354
> URL: https://issues.apache.org/jira/browse/HBASE-4354
> Project: HBase
> Issue Type: New Feature
> Components: master, metrics, regionserver
> Reporter: Ming Ma
> Assignee: Ming Ma
>
> For debugging and analysis purposes it will be useful to understand regions'
> lifecycle, how it is created ( from which parent region, for example), how it
> is splitted, assigned, etc. Some of these info are in the logs, hbase .META.
> table, zookeeper, metrics. Certain history data is lost; for example, the
> states will be removed from zookeeper /hbase/unassigned once the region is
> assigned; also .META. table has max version of 10 thus only tracks the last
> 10 RS assignments of a given region. It will be nice to put it a central
> place. It can provide:
> 1. How applications use hbase. For example, it might create large number of
> regions in a short period of time and drop the table later.
> 2. How HBase internally manage regions such as how regions are splitted,
> assigned, turned offline, etc.
> Things to track
> 1. How it is created, parent region in the case of split.
> 2. Region tranisition process such as region state change, region server
> change.
> One idea is to put such transition history data to zookeeper. One issue is it
> could blow up zookeeper memory if we have large number of regions and the
> cluster runs for a long time. I would like to get your feedback on different
> approaches to address the issue. One assumption is region assignment doesn't
> happen with high frequency and thus the overhead introduced won't have much
> impact on the system performance.
> Approach 1:
> Zookeeper knows the history of how /hbase/unassigned is modified, if we can
> get zookeeper's logs (Bookkeeper ? ) somehow, we know the history of region
> transition.
> Approach 2:
> 1. HBase logs extra region transition data to zookeeper. It could be one
> zookeeper node per transaction.
> 2. Have a separate thread on the Master to move data from zookeeper and
> append to HDFS. That will keep the zookeeper size in check.
> 3. Have some tool or web UI to show the history of a given region by
> looking at zookeeper and HDFS.
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