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From "Jeff Jirsa (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-10276) With DTCS, do STCS in windows if more than max_threshold sstables
Date Mon, 07 Sep 2015 22:03:45 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-10276?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14734051#comment-14734051
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Jeff Jirsa commented on CASSANDRA-10276:
----------------------------------------


If your most recent window/bucket with compactable sstables has more than max_threshold sstables,
but they're sized in such a way that stcs won't combine any of them, {{SizeTieredCompactionStrategy.mostInterestingBucket}}
may return empty, which then causes {{trimToThreshold}} and {{newestBucket}} to return empty
lists.  If you may have older buckets that could otherwise be compacted in some way, they'll
starve. If you check to see if {{SizeTieredCompactionStrategy.mostInterestingBucket(...).isEmpty()}}
, you can continue to check older time windows/buckets/targets. 

This also impacts calculation of {{estimatedRemainingTasks}} 

Other than that it looks good. 

> With DTCS, do STCS in windows if more than max_threshold sstables
> -----------------------------------------------------------------
>
>                 Key: CASSANDRA-10276
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-10276
>             Project: Cassandra
>          Issue Type: Sub-task
>          Components: Core
>            Reporter: Marcus Eriksson
>            Assignee: Marcus Eriksson
>             Fix For: 3.x, 2.1.x, 2.2.x
>
>
> To avoid constant recompaction of files in big ( > max threshold) DTCS windows, we
should do STCS of those files.
> Patch here: https://github.com/krummas/cassandra/commits/marcuse/dtcs_stcs



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