Takenori Sato created CASSANDRA-8866:
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Summary: PartitionedCompactionStrategy
Key: CASSANDRA-8866
URL: https://issues.apache.org/jira/browse/CASSANDRA-8866
Project: Cassandra
Issue Type: New Feature
Reporter: Takenori Sato
Fix For: 2.0.12
PartitionedCompactionStrategy is a new compaction strategy with the following
goals in mind:
* Column tombstone removal effectiveness
* Read performance
As the name suggests, PartitionedCompactionStrategy actively splits
un-partitioned sstables(newly flushed, imported, compaction strategy switch)
into partitions by IPartitioner. The number of nodes will be configurable.
Then, PartitionedCompactionStrategy finds an interesting partition at
compaction based on the followings:
- the number of sstables
- the ratio of droppable tombstones
- read hotness
You may think this design looks similar to SizeTieredCompactionStrategy and
LeveledCompactionStrategy, but the big difference is that a compaction by
PartitionedCompactionStrategy is based on rows(a partitions). And this allows
more effective column tombstone removal, and better read performance.
Also note that this will not require any changes to the other components. So
this is expected to be a purely pluggable compaction strategy.
A possible implementation of
_PertitionedCompactionStrategy#getNextBackgroundTask()_ is as follows:
# find un-partitioned sstables
# split un-partitioned sstables into partitiones
# group all the sstables into partitions
# find an interesting partition
#* the number of sstables
#* the number of droppable tombstones
#* hotness
# create a compaction task for the interesting bucket if found
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