Aleksey Yeschenko created CASSANDRA-6880:
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Summary: counters++ lock on cells, not partitions
Key: CASSANDRA-6880
URL: https://issues.apache.org/jira/browse/CASSANDRA-6880
Project: Cassandra
Issue Type: Improvement
Reporter: Aleksey Yeschenko
Assignee: Aleksey Yeschenko
Fix For: 2.1 beta2
I'm starting to think that we should switch to locking by cells, not by
partitions, when updating counters.
With the current 2.1 counters, if nothing changes, the new recommendation would
become "use smaller partitions, batch updates to the same partition", and that
goes against what we usually recommend:
1. Prefer wide partitions to narrow partitions
2. Don't batch counter updates (because you risk to exaggerate
undercounting/overcounting in case of a timeout)
Locking on cells would cause C* to have to grab more locks for batch counter
updates, but would give us generally more predictable performance (independent
of partition wideness), and won't force people to remodel their data model if
they have often concurrently-updated counters in the same few wide partitions.
(It's a small change, code-wise)
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