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https://issues.apache.org/jira/browse/CASSANDRA-6880?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13951398#comment-13951398
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Aleksey Yeschenko commented on CASSANDRA-6880:
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The old (pre-1.2) index locks were per-keyspace. I'm more inclined to go global
this time, though. Whether to go 1024 * CW or higher is an open question
though. FWIW I'm not committing this until the current batch of CASSANDRA-6553
and the next one (with changed params + some new tests) are run, so feel free
to keep brainstorming here.
> 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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