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From "Jonathan Ellis (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-2449) Deprecate or modify per-cf memtable sizes in favor of the global threshold
Date Mon, 11 Apr 2011 19:36:05 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-2449?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13018528#comment-13018528
] 

Jonathan Ellis commented on CASSANDRA-2449:
-------------------------------------------

bq. replace them with a preference value, which controls the relative memory usage of one
CF versus another

I'm not a fan of adding additional complexity here.  At best, you'll get substantially the
current behavior; at worst (when you tell it to prefer keeping the largest CF in memory),
you'll create a flush storm of smaller CFs.

> Deprecate or modify per-cf memtable sizes in favor of the global threshold
> --------------------------------------------------------------------------
>
>                 Key: CASSANDRA-2449
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-2449
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: Core
>            Reporter: Stu Hood
>             Fix For: 0.8
>
>
> The new memtable_total_space_in_mb setting is an excellent way to cap memory usage for
memtables, and one could argue that it should replace the per-cf memtable sizes entirely.
On the other hand, people may still want a knob to tune to flush certain cfs less frequently.
> I think a best of both worlds approach might be to deprecate the memtable_(throughput|operations)
settings, and replace them with a preference value, which controls the relative memory usage
of one CF versus another (all CFs at 1 would mean equal preference). For backwards compatibility,
we could continue to read from the _throughput value and treat it as the preference value,
while logging a warning.

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