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From Charles Brophy <cbro...@zulily.com>
Subject Re: Size Tiered -> Leveled Compaction
Date Thu, 14 Feb 2013 16:29:28 GMT
I second these questions: we've been looking into changing some of our CFs
to use leveled compaction as well. If anybody here has the wisdom to answer
them it would be of wonderful help.

Thanks
Charles

On Wed, Feb 13, 2013 at 7:50 AM, Mike <mtheroux2@yahoo.com> wrote:

> Hello,
>
> I'm investigating the transition of some of our column families from Size
> Tiered -> Leveled Compaction.  I believe we have some high-read-load column
> families that would benefit tremendously.
>
> I've stood up a test DB Node to investigate the transition.  I
> successfully alter the column family, and I immediately noticed a large
> number (1000+) pending compaction tasks become available, but no compaction
> get executed.
>
> I tried running "nodetool sstableupgrade" on the column family, and the
> compaction tasks don't move.
>
> I also notice no changes to the size and distribution of the existing
> SSTables.
>
> I then run a major compaction on the column family.  All pending
> compaction tasks get run, and the SSTables have a distribution that I would
> expect from LeveledCompaction (lots and lots of 10MB files).
>
> Couple of questions:
>
> 1) Is a major compaction required to transition from size-tiered to
> leveled compaction?
> 2) Are major compactions as much of a concern for LeveledCompaction as
> their are for Size Tiered?
>
> All the documentation I found concerning transitioning from Size Tiered to
> Level compaction discuss the alter table cql command, but I haven't found
> too much on what else needs to be done after the schema change.
>
> I did these tests with Cassandra 1.1.9.
>
> Thanks,
> -Mike
>

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