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From "Jeffrey Zhong (JIRA)" <j...@apache.org>
Subject [jira] [Created] (HBASE-11315) Keeping MVCC for configurable longer time
Date Tue, 10 Jun 2014 02:21:01 GMT
Jeffrey Zhong created HBASE-11315:

             Summary: Keeping MVCC for configurable longer time 
                 Key: HBASE-11315
                 URL: https://issues.apache.org/jira/browse/HBASE-11315
             Project: HBase
          Issue Type: Improvement
    Affects Versions: 0.99.0
            Reporter: Jeffrey Zhong
            Assignee: Jeffrey Zhong

After hbase-8763, we need keep mvcc number longer in hfile so that it can be used to order
changes during writes. For example, the known put,delete,put,... scenario, cross region server
scan, out of order puts(in recovery case).

Current thinking is that we make the retention period configurable(below we're using 1 day
to explain). During major compaction, we check hfile's creation time if a hfile creation time
is older than 1 day then all mvcc of KVs in that hfile will be removed. If a hfile is created
within 1 day, then all mvccs of KVs in that hfile will be kept. 

In case there are time clock skew, we can firstly sort hfiles based on its seqId in ascending
order and find the first hfile's creation time stamp less than 1 day. Then mvcc of all hfiles
before the found file will be removed during compaction. 

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