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From "Etienne Adam (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 Thu, 14 May 2015 20:41:00 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-8340?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14544330#comment-14544330
] 

Etienne Adam commented on CASSANDRA-8340:
-----------------------------------------

We have the same issue in 2.1.5, converting a CF from STCS to DTCS: one huge sstable keeps
getting compacted... The compaction takes more than 10 hours and runs very often (at least
every day), causing a constant load on all nodes.
I think that having a "max_window_size" would solve this problem, as this sstable would immediately
stop compacting, even with a high setting of 1 month.

> 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
>
> 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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