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From "Marcus Eriksson (JIRA)" <j...@apache.org>
Subject [jira] [Created] (CASSANDRA-8833) Stop opening compaction results early
Date Thu, 19 Feb 2015 14:45:14 GMT
Marcus Eriksson created CASSANDRA-8833:
------------------------------------------

             Summary: Stop opening compaction results early
                 Key: CASSANDRA-8833
                 URL: https://issues.apache.org/jira/browse/CASSANDRA-8833
             Project: Cassandra
          Issue Type: Improvement
            Reporter: Marcus Eriksson
             Fix For: 2.1.4


We should simplify the code base by not doing early opening of compaction results. It makes
it very hard to reason about sstable life cycles since they can be in many different states,
"opened early", "starts moved", "shadowed", "final", instead of as before, basically just
one (tmp files are not really 'live' yet so I don't count those). The ref counting of shared
resources between sstables in these different states is also hard to reason about. This has
caused quite a few issues since we released 2.1

I think it all boils down to a performance vs code complexity issue, is opening compaction
results early really 'worth it' wrt the performance gain? The results in CASSANDRA-6916 sure
look like the benefits are big enough, but the difference should not be as big for people
on SSDs (which most people who care about latencies are)

WDYT [~benedict] [~jbellis] [~iamaleksey] [~JoshuaMcKenzie]?



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