Improvement to CompactionManger's submitMinorIfNeeded
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Key: CASSANDRA-1083
URL: https://issues.apache.org/jira/browse/CASSANDRA-1083
Project: Cassandra
Issue Type: Improvement
Affects Versions: 0.6.1
Reporter: Ryan King
Assignee: Ryan King
Priority: Minor
We've discovered that we are unable to tune compaction the way we want for our
production cluster. I think the current algorithm doesn't do this as well as it
could, since it doesn't sort the sstables by size before doing the bucketing,
which means the tuning parameters have unpredictable results.
I looked at CASSANDRA-792, but it seems like overkill. Here's an alternative
proposal:
config operations:
minimumCompactionThreshold
maximumCompactionThreshold
targetSSTableCount
The first two would mean what they currently mean: the bounds on how many
sstables to compact in one compaction operation. The 3rd is a target for how
many SSTables you'd like to have.
Pseudo code algorithm for determining whether or not to do a minor compaction:
if sstables.length > targetSSTableCount
sort sstables from smallest to largest
if sstables.length - targetSSTableCount > minimumCompactionThreshold
compact the up to maximumCompactionThreshold smallest tables
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