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https://issues.apache.org/jira/browse/CASSANDRA-10496?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15988457#comment-15988457
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Marcus Eriksson commented on CASSANDRA-10496:
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you need to inspect the timestamp on each cell in each partition and split
based on that
> Make DTCS/TWCS 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: 3.11.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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