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From "Victor Xu (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HBASE-11397) When merging expired stripes, we need to create an empty file to preserve metadata.
Date Sun, 22 Jun 2014 09:30:24 GMT

     [ https://issues.apache.org/jira/browse/HBASE-11397?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Victor Xu updated HBASE-11397:
------------------------------

    Attachment: HBASE-11397-HDFS.png

Attach the accumulated expired stripe files.

> When merging expired stripes, we need to create an empty file to preserve metadata.
> -----------------------------------------------------------------------------------
>
>                 Key: HBASE-11397
>                 URL: https://issues.apache.org/jira/browse/HBASE-11397
>             Project: HBase
>          Issue Type: Bug
>          Components: Compaction
>    Affects Versions: 0.98.2
>         Environment: jdk1.7.0_45, hadoop-cdh5, hbase-0.98.2
>            Reporter: Victor Xu
>         Attachments: HBASE-11397-HDFS.png, HBASE-11397-Stripe-Info.png
>
>
> Stripe Compaction is a good feature in 0.96 and 0.98. But when I used it in a heavy-write
non-uniform row keys scenario(e.g. time dimension in a key), I came across some problems.

> I made my stripes split at the size of 2G(hbase.store.stripe.sizeToSplit=2G), and soon
there were tens of them. It was true that only the last stripe receiving the new keys kept
compacting - old data didn't compact as much, or at all. However, the old stripes were still
there when they all expired. I checked the source code and found that when compacting expired
stripes, the StoreScanner may return no KVs so that SizeMultiWriter.append() is never called.
That's to say, NO NEW FILE WILL BE CREATED. 
> My solution is to create an empty file to preserve metadata at the end of the SizeMultiWriter.commitWritersInternal().



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