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From "Marcus Eriksson (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-8340) Use sstable min timestamp when deciding if an sstable should be included in DTCS compactions
Date Mon, 01 Jun 2015 07:45:18 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-8340?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14567035#comment-14567035
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Marcus Eriksson commented on CASSANDRA-8340:
--------------------------------------------

I doubt we should introduce this now - having many hard-to-explain configuration options is
bad thing.

For your use case, you should probably just run a custom compaction strategy as I really hope
it is not a common problem. For the people migrating from STCS, we should probably build a
major compaction for DTCS that splits data based on its timestamps, but I have not heard any
complaints about issues when migrating to DTCS from STCS since DTCS was introduced.

> Use sstable min timestamp when deciding if an sstable should be included in DTCS compactions
> --------------------------------------------------------------------------------------------
>
>                 Key: CASSANDRA-8340
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-8340
>             Project: Cassandra
>          Issue Type: Improvement
>            Reporter: Marcus Eriksson
>            Priority: Minor
>         Attachments: 8340-v2.diff, 8340.diff
>
>
> Currently we check how old the newest data (max timestamp) in an sstable is when we check
if it should be compacted.
> If we instead switch to using min timestamp for this we have a pretty clean migration
path from STCS/LCS to DTCS. 
> My thinking is that before migrating, the user does a major compaction, which creates
a huge sstable containing all data, with min timestamp very far back in time, then switching
to DTCS, we will have a big sstable that we never compact (ie, min timestamp of this big sstable
is before max_sstable_age_days), and all newer data will be after that, and that new data
will be properly compacted
> WDYT [~Bj0rn] ?



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