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From "Stu Hood (JIRA)" <>
Subject [jira] [Commented] (CASSANDRA-2006) Serverwide caps on memtable thresholds
Date Tue, 05 Apr 2011 06:52:05 GMT


Stu Hood commented on CASSANDRA-2006:

Since the only one consuming the getLiveSize value is the MeteredFlusher thread, could the
live-size update be moved into that thread instead? Adding a new executor and 2 new tasks
seems like overkill, and it looks like it would remove the "potentially a flushed memtable
being counted by jamm" fuzziness.

> Serverwide caps on memtable thresholds
> --------------------------------------
>                 Key: CASSANDRA-2006
>                 URL:
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: Core
>            Reporter: Stu Hood
>             Fix For: 0.8
>         Attachments: 2006-v2.txt, 2006.txt, jamm-0.2.jar
> By storing global operation and throughput thresholds, we could eliminate the "many small
memtables" problem caused by having many CFs. The global threshold would be set in the config
file, to allow different classes of servers to have different values configured.
> Operations occurring in the memtable would add to the global counters, in addition to
the memtable-local counters. When a global threshold was violated, the memtable in the system
that was using the largest fraction of it's local threshold would be flushed. Local thresholds
would continue to act as they always have.
> The result would be larger sstables, safer operation with multiple CFs and per node tuning.

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