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https://issues.apache.org/jira/browse/CASSANDRA-7282?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14104970#comment-14104970
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Ryan McGuire edited comment on CASSANDRA-7282 at 8/21/14 4:10 AM:
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Thanks Benedict, I tried it with those new settings. Still using
memtable_cleanup_threshold of 0.5 :
http://riptano.github.io/cassandra_performance/graph_v3/graph.html?stats=stats.7282.3.json
Getting a bit more interesting now, not sure what's up with that first read and
then the drop.
EDIT: a second run of this shows similar results:
http://riptano.github.io/cassandra_performance/graph_v3/graph.html?stats=stats.7282.3-redo.json&metric=op_rate&operation=2_read&smoothing=1&show_aggregates=true&xmin=0&xmax=389.62&ymin=0&ymax=196953.9
I'll try scaling up memtable_cleanup_threshold again.
was (Author: enigmacurry):
Thanks Benedict, I tried it with those new settings. Still using
memtable_cleanup_threshold of 0.5 :
http://riptano.github.io/cassandra_performance/graph_v3/graph.html?stats=stats.7282.3.json
Getting a bit more interesting now, not sure what's up with that first read and
then the drop.
I'll try scaling up memtable_cleanup_threshold again.
> 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.
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