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https://issues.apache.org/jira/browse/CASSANDRA-8361?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15092967#comment-15092967
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Wei Deng commented on CASSANDRA-8361:
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Should this now be considered as a duplicate to CASSANDRA-10496?
> Make DTCS split SSTables to perfectly fit time windows
> ------------------------------------------------------
>
> Key: CASSANDRA-8361
> URL: https://issues.apache.org/jira/browse/CASSANDRA-8361
> Project: Cassandra
> Issue Type: Improvement
> Reporter: Björn Hegerfors
> Priority: Minor
>
> The time windows that DTCS uses are what the strategy tries to align SSTables
> to, in order to get the right structure, for best performance. I added the
> ticket CASSANDRA-8360, taking SSTables one step closer to aligning with these
> windows in a 1:1 manner.
> The idea in this ticket is to perfectly align SSTables with the DTCS time
> windows, by splitting SSTables that cross window borders. This can lead to
> certain benefits, perhaps mostly in consistency and predictability terms,
> where it will be very well defined where every value is stored that is old
> enough to have stabilized.
> Read queries can be aligned with windows in order to guarantee a single disk
> seek (although then the client needs to know the right window placements).
> Basically, SSTables can be made to align perfectly on day borders, for
> example. Right now, there would be an SSTable that almost represents a day,
> but not perfectly. So some data is still in another SSTable.
> It could also be a useful property for tombstone expiration and repairs.
> Practically all splits would happen only in the latest time windows with the
> newest and smallest SSTables. After those are split, DTCS would never compact
> SSTables across window borders. I have a hard time seeing when this could
> cause an expensive operation except for when switching from another
> compaction strategy (or even from current DTCS), and after a major
> compaction. In fact major compaction for DTCS should put data perfectly in
> windows rather than everything in one SSTable.
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