Jonathan Ellis created CASSANDRA-11206:
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Summary: Support large partitions on the 3.0 sstable format
Key: CASSANDRA-11206
URL: https://issues.apache.org/jira/browse/CASSANDRA-11206
Project: Cassandra
Issue Type: Improvement
Reporter: Jonathan Ellis
Fix For: 3.x
Cassandra saves a sample of IndexInfo objects that store the offset within each
partition of every 64KB (by default) range of rows. To find a row, we binary
search this sample, then scan the partition of the appropriate range.
The problem is that this scales poorly as partitions grow: on a cache miss, we
deserialize the entire set of IndexInfo, which both creates a lot of GC
overhead (as noted in CASSANDRA-9754) but is also non-negligible i/o activity
(relative to reading a single 64KB row range) as partitions get truly large.
We introduced an "offset map" in CASSANDRA-10314 that allows us to perform the
IndexInfo bsearch while only deserializing IndexInfo that we need to compare
against, i.e. log(N) deserializations.
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