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From "Tyler Hobbs (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-5515) Track sstable coldness
Date Thu, 01 Aug 2013 21:11:50 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-5515?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13726900#comment-13726900
] 

Tyler Hobbs commented on CASSANDRA-5515:
----------------------------------------

With that in mind, I'm leaning towards using Metric's [Meters|http://metrics.codahale.com/manual/core/#meters],
which have pretty low overhead and would be be easy to dump and restore.  The only flaw is
that they are hard-coded with 1m, 5m, and 15m windows; for compaction decisions, I feel like
it would be nice to have a multi-hour window, and the 1 and 5m are probably too short to be
useful for CASSANDRA-5519 (if we do something similar to my suggestion on that ticket).  We
could of course subclass and hardcode with windows of our choosing.
                
> Track sstable coldness
> ----------------------
>
>                 Key: CASSANDRA-5515
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-5515
>             Project: Cassandra
>          Issue Type: New Feature
>          Components: Core
>            Reporter: Jonathan Ellis
>            Assignee: Tyler Hobbs
>             Fix For: 2.0.1
>
>         Attachments: 0001-Track-row-read-counts-in-SSTR.patch
>
>
> Keeping a count of reads per-sstable would allow STCS to automatically ignore cold data
rather than recompacting it constantly with hot data, dramatically reducing compaction load
for typical time series applications and others with time-correlated access patterns.  We
would not need a separate age-tiered compaction strategy.
> (This will really be useful in conjunction with CASSANDRA-5514.)

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