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From Franc Carter <franc.car...@sirca.org.au>
Subject Re: Updated sstable size for LCS, ran upgradesstables, file sizes didn't change
Date Sat, 22 Jun 2013 09:14:13 GMT
On Sat, Jun 22, 2013 at 10:42 AM, Wei Zhu <wz1975@yahoo.com> wrote:

> I think the new SSTable will be in the new size. In order to do that, you
> need to trigger a compaction so that the new SSTables will be generated.
> for LCS, there is no major compaction though. You can run a nodetool repair
> and hopefully you will bring some new SSTables and compactions will kick in.
> Or you can change the $CFName.json file under your data directory and move
> every SSTable to level 0. You need to stop your node,  write a simple
> script to alter that file and start the node again.
>
> I think it will be helpful to have a nodetool command to change the
> SSTable Size and trigger the rebuild of the SSTables.
>


I'd find that useful as well

cheers


>
> Thanks.
> -Wei
>
> ------------------------------
> *From: *"Robert Coli" <rcoli@eventbrite.com>
> *To: *user@cassandra.apache.org
> *Sent: *Friday, June 21, 2013 4:51:29 PM
> *Subject: *Re: Updated sstable size for LCS, ran upgradesstables, file
> sizes didn't change
>
>
> On Fri, Jun 21, 2013 at 4:40 PM, Andrew Bialecki
> <andrew.bialecki@gmail.com> wrote:
> > However when we run alter the column
> > family and then run "nodetool upgradesstables -a keyspace columnfamily,"
> the
> > files in the data directory have been re-written, but the file sizes are
> the
> > same.
> >
> > Is this the expected behavior? If not, what's the right way to upgrade
> them.
> > If this is expected, how can we benchmark the read/write performance with
> > varying sstable sizes.
>
> It is expected, upgradesstables/scrub/clean compactions work on a
> single sstable at a time, they are not capable of combining or
> splitting them.
>
> In theory you could probably :
>
> 1) start out with the largest size you want to test
> 2) stop your node
> 3) use sstable_split [1] to split sstables
> 4) start node, test
> 5) repeat 2-4
>
> I am not sure if there is anything about level compaction which makes
> this infeasible.
>
> =Rob
> [1] https://github.com/pcmanus/cassandra/tree/sstable_split
>
>


-- 

*Franc Carter* | Systems architect | Sirca Ltd
 <marc.zianideferranti@sirca.org.au>

franc.carter@sirca.org.au | www.sirca.org.au

Tel: +61 2 8355 2514

Level 4, 55 Harrington St, The Rocks NSW 2000

PO Box H58, Australia Square, Sydney NSW 1215

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