[ https://issues.apache.org/jira/browse/CASSANDRA-7282?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14132586#comment-14132586 ]
Benedict commented on CASSANDRA-7282: ------------------------------------- Perhaps this is a good opportunity, for our second set of data points, to try taking the latest 'realistic workload' features of cassandra-stress for a whirl > 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 > > Attachments: reads.svg, writes.svg > > > 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 (v6.3.4#6332)