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From "Jeff Jirsa (JIRA)" <j...@apache.org>
Subject [jira] [Issue Comment Deleted] (CASSANDRA-10496) Make DTCS split partitions based on time during compaction
Date Tue, 12 Jan 2016 01:25:39 GMT

     [ https://issues.apache.org/jira/browse/CASSANDRA-10496?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Jeff Jirsa updated CASSANDRA-10496:
-----------------------------------
    Comment: was deleted

(was: [~krummas] - why not make 3 resulting sstables - one earlier, one later, and one exactly
on target? The marginal cost of the third sstable seems pretty minor. The benefit seems relatively
significant? 
)

> Make DTCS split partitions based on time during compaction
> ----------------------------------------------------------
>
>                 Key: CASSANDRA-10496
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-10496
>             Project: Cassandra
>          Issue Type: Improvement
>            Reporter: Marcus Eriksson
>              Labels: dtcs
>             Fix For: 3.x
>
>
> To avoid getting old data in new time windows with DTCS (or related, like [TWCS|CASSANDRA-9666]),
we need to split out old data into its own sstable during compaction.
> My initial idea is to just create two sstables, when we create the compaction task we
state the start and end times for the window, and any data older than the window will be put
in its own sstable.
> By creating a single sstable with old data, we will incrementally get the windows correct
- say we have an sstable with these timestamps:
> {{[100, 99, 98, 97, 75, 50, 10]}}
> and we are compacting in window {{[100, 80]}} - we would create two sstables:
> {{[100, 99, 98, 97]}}, {{[75, 50, 10]}}, and the first window is now 'correct'. The next
compaction would compact in window {{[80, 60]}} and create sstables {{[75]}}, {{[50, 10]}}
etc.
> We will probably also want to base the windows on the newest data in the sstables so
that we actually have older data than the window.



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