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From "Marcus Eriksson (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-11550) Make the fanout size for LeveledCompactionStrategy to be configurable
Date Tue, 30 Aug 2016 06:40:20 GMT

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Marcus Eriksson commented on CASSANDRA-11550:
---------------------------------------------

So, starting from 40gb unleveled data we get this with fanout = 6:
* 5% longer time to compact
* 10% more compaction bytes written
* 2% larger live size after compaction

I guess all those numbers are due to the fact that we end up with more levels and we need
to do more compaction to get the data into those levels

These numbers are not 100% fair either as what is most interesting is a steady-state situation,
but that is much harder to benchmark. I'll set up a 2 node cluster and change one of them
to use fanout = 6 and run stress.

> Make the fanout size for LeveledCompactionStrategy to be configurable
> ---------------------------------------------------------------------
>
>                 Key: CASSANDRA-11550
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-11550
>             Project: Cassandra
>          Issue Type: New Feature
>          Components: Compaction
>            Reporter: Dikang Gu
>            Assignee: Dikang Gu
>              Labels: lcs
>             Fix For: 3.x
>
>         Attachments: 0001-make-fanout-size-for-leveledcompactionstrategy-to-be.patch
>
>
> Currently, the fanout size for LeveledCompactionStrategy is hard coded in the system
(10). It would be useful to make the fanout size to be tunable, so that we can change it according
to different use cases.
> Further more, we can change the size dynamically.



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