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From "Jonathan Ellis (JIRA)" <j...@apache.org>
Subject [jira] Updated: (CASSANDRA-622) better commitlog performance
Date Mon, 18 Jan 2010 19:22:54 GMT

     [ https://issues.apache.org/jira/browse/CASSANDRA-622?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Jonathan Ellis updated CASSANDRA-622:
-------------------------------------

    Fix Version/s:     (was: 0.6)

> better commitlog performance
> ----------------------------
>
>                 Key: CASSANDRA-622
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-622
>             Project: Cassandra
>          Issue Type: Improvement
>            Reporter: Jonathan Ellis
>            Priority: Minor
>
> Postgresql uses fixed-size commitlog files that it pre-allocates (filling with zeros)
so "appending" to the log can use cheaper fsync-without-metadata (length changes is "metadata").
 Then, when a commitlog is not needed, it "recycles" it by renaming it to a higher number.
 Commitlog entries have an increasing id, and if you come to an out-of-sequence (earlier)
id, then you must have have reached the end of the commitlog and are reading from the "recycled"
part.

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