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Ryan McGuire commented on CASSANDRA-7282: ----------------------------------------- Here's a test run with default settings. We fared just slightly better than stock. http://riptano.github.io/cassandra_performance/graph_v3/graph.html?stats=stats.7282.defaults.json Tomorrow I'll run a test incorporating [~benedict]'s suggestions regarding memtable and row size adjustments. > Faster Memtable map > ------------------- > > Key: CASSANDRA-7282 > URL: https://issues.apache.org/jira/browse/CASSANDRA-7282 > Project: Cassandra > Issue Type: Improvement > Components: Core > Reporter: Benedict > Assignee: Benedict > Labels: performance > Fix For: 3.0 > > > Currently we maintain a ConcurrentSkipLastMap of DecoratedKey -> Partition in > our memtables. Maintaining this is an O(lg(n)) operation; since the vast > majority of users use a hash partitioner, it occurs to me we could maintain a > hybrid ordered list / hash map. The list would impose the normal order on the > collection, but a hash index would live alongside as part of the same data > structure, simply mapping into the list and permitting O(1) lookups and > inserts. > I've chosen to implement this initial version as a linked-list node per item, > but we can optimise this in future by storing fatter nodes that permit a > cache-line's worth of hashes to be checked at once, further reducing the > constant factor costs for lookups. -- This message was sent by Atlassian JIRA (v6.2#6252)