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From Yuki Morishita <mor.y...@gmail.com>
Subject Re: Automatic tombstone compaction
Date Wed, 21 Aug 2013 15:23:46 GMT
Tamas,

If there are rows with the same key in other SSTables, that rows won't
be deleted.
Tombstone compaction make guess if it can actually drop "safely" by
scanning overlap with other SSTables.
Do you have many rows in your large SSTable?
If you don't, then chance to run tombstone compaction may be low.


On Wed, Aug 21, 2013 at 9:33 AM,  <tamas.foldesi@thomsonreuters.com> wrote:
> Hi,
>
>
>
> I ran upgradesstables as part of the Cassandra upgrade, before issuing the
> CQL alter command.
>
> According to the docs, SizeTieredCompactionStrategy is fine (that is what I
> used, and plan on continue using), and automatic tombstone compaction is
> available for it:
>
> http://www.datastax.com/documentation/cassandra/1.2/webhelp/index.html#cassandra/operations/ops_about_config_compact_c.html
>
> I just had to include the ‘class’ in the alter statement, otherwise it would
> not accept my command.
>
> Is that not right?
>
>
>
> Thanks,
>
> Tamas
>
>
>
> From: Haithem Jarraya [mailto:a-hjarraya@expedia.com]
> Sent: 21. august 2013 16:24
> To: user@cassandra.apache.org
> Subject: Re: Automatic tombstone compaction
>
>
>
> Hi,
>
>
>
> do you mean LeveledCompactionStrategy?
>
>
>
> Also you will need to run nodetool upgradesstables  [keyspace][cf_name]
> after changing the compaction strategy.
>
>
>
> Thanks,
>
>
>
> Haithem Jarraya
>
> On 21 Aug 2013, at 15:15, tamas.foldesi@thomsonreuters.com wrote:
>
>
>
> Hi,
>
>
>
> After upgrading from 1.0 to 1.2, I wanted to make use of the automatic
> tombstone compaction feature, so using CQL3 I issued:
>
>
>
> ALTER TABLE versions WITH compaction = {'class' :
> 'SizeTieredCompactionStrategy', 'min_threshold' : 4, 'max_threshold' : 32,
> 'tombstone_compaction_interval' : 1, 'tombstone_threshold' : '0.1'};
>
>
>
> But I still see no trace that would suggest this works – we had 60G of data
> with TTL=1week pushed a while ago to the test cluster, the majority of it
> should be expired & compacted away by now. Not sure if it is relevant, but
> this old data is in one ~60G file + I have a few smaller files with latest
> data in them.
>
> Looking at JMX: DroppableTombstoneRatio = 0.892076544, which seems to back
> my theory.
>
> Am I doing something wrong, or am I expecting the wrong thing?
>
>
>
> Thanks,
>
> Tamas
>
>
>
>



-- 
Yuki Morishita
 t:yukim (http://twitter.com/yukim)

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