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From "Sean Thornton (JIRA)" <>
Subject [jira] [Created] (CASSANDRA-10976) Improve Tombstone Compaction to respect Partitioner
Date Wed, 06 Jan 2016 21:39:39 GMT
Sean Thornton created CASSANDRA-10976:

             Summary: Improve Tombstone Compaction to respect Partitioner
                 Key: CASSANDRA-10976
             Project: Cassandra
          Issue Type: Improvement
          Components: Compaction
            Reporter: Sean Thornton

It would be nice to have AbstractCompactionStrategy.worthDroppingTombstones changed to use
the partitioner to help decide when to compact.  It appears that back in CASSANDRA-6563, unchecked_tombstone_compaction
was added to try and address this but it is turned off by default.

The problem I have with this method is it was built when OrderedPartitioner was more the norm
(vs. Random/Murmur today) and the checks it performs are still based on that assumption.

So my thought would be to update worthDroppingTombstones to get rid of unchecked_tombstone_compaction
and do something like the following pseudo -
// do the early escape checks...
if (ssTableTooNew) return false;
if (droppableRatio <= tombstoneThreshold) return false;

// use the partitioner to try to be smart about it
if (sstable.partitioner.preservesOrder()) {
    // do the range/overlap checks done today and return...
} else {
    return true;

Found in 2.0.14 but looking around seems to be present in newer branches as well.

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