range-based log(n) elimination of sstables in read path
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Key: CASSANDRA-4011
URL: https://issues.apache.org/jira/browse/CASSANDRA-4011
Project: Cassandra
Issue Type: Improvement
Components: Core
Reporter: Peter Schuller
If the read path was able to eliminate sstables based on token ranges, we would
avoid {{O(n)}} bloom filter checks ({{n}} being number of sstables).
Contributing motivation:
* For maximally efficient bulk-import, you tend to want a lot of small sstables
to avoid having to build up huge ones during the bulk creation process.
* To avoid having to keep duplicate data when switching a data set (in a
periodic bulk replace import process), keeping sstables partitioned on token
range (similarly to leveled compaction) allows in-place replacement of sstables
one sstable at a time.
Those two in combination would mean that you can run a bulk-import based
total-dataset-replacement cluster with zero compaction and with zero disk space
overhead stemming from having to have overhead for compaction.
In addition:
* For e.g. leveled compaction where we have range based partitioning anyway,
{{log(n)}} is preferable to {{o(n)}}; especially if it would allow us to have
more than 10 "partitions" per level. I'm not sure yet whether there are other
reasons to have "only" 10, but if we can make them smaller by eliminating the
{{o(n)}} behavior in the read path, individual compactions can be even smaller
with leveled and you would scale even more easily with large data sets while
avoiding build-up in L0.
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