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From "Kannan Muthukkaruppan (JIRA)" <j...@apache.org>
Subject [jira] Created: (HBASE-3048) unify code for major/minor compactions
Date Wed, 29 Sep 2010 00:20:32 GMT
unify code for major/minor compactions
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                 Key: HBASE-3048
                 URL: https://issues.apache.org/jira/browse/HBASE-3048
             Project: HBase
          Issue Type: Improvement
            Reporter: Kannan Muthukkaruppan


Today minor compactions do not process deletes, purge old versions, etc. Only major compactions
do.  The rationale was probably to save CPU (?). We should evaluate if major compaction logic
indeed runs significantly slower.

Unifying minor compactions to do the same thing as major compactions has other advantages:

* If the same data is overwritten several times and we are not processing overwrites, it makes
each subsequent minor compaction more expensive as the total amount of data.

* We'll have fewer bugs if the logic is as symmetric as possible. Any bugs in TTL enforcement,
version enforcement, etc. could cause behavior to be different after a major compaction. Keeping
the same logic means these bugs will get caught earlier.

-

Note: There will still need to be one difference in the two schemes, and that has to do with
delete markers. Any compaction which doesn't compact all files will still need to leave delete
markers.


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