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Date: Wed, 4 Apr 2012 09:17:12 +0200
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Subject: Re: System keyspace leak?
From: Sylvain Lebresne <sylvain@datastax.com>
To: user@cassandra.apache.org
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On Wed, Apr 4, 2012 at 3:14 AM, David Leimbach <leimy2k@gmail.com> wrote:
> Well I just found this:
>
> http://wiki.apache.org/cassandra/LiveSchemaUpdates
>
> which explains a ton... =A0It looks like this particular Column Family wi=
ll
> grow infinitely (it's just one row with a column per migration), so if I'=
m
> pounding on my Cassandra node with CREATE/DROP activity, I'm going to mak=
e
> VERY wide row.
>
> That tells me enough to say "don't do that!" =A0:-)

All that is true in 1.0 but know that we've "fixed" it in the upcoming
1.1 (http://www.datastax.com/dev/blog/the-schema-management-renaissance).

--
Sylvain


>
> Dave
>
> On Tue, Apr 3, 2012 at 6:00 PM, David Leimbach <leimy2k@gmail.com> wrote:
>>
>> I've been trying to understand the overhead of create/drop keyspace on
>> Cassandra 1.0.8. =A0It's not free, especially when I've managed to drive=
 up
>> the LiveDiskSpaceUsed for the Migrations CF in the "system" keyspace up =
to
>> over 12 MB of disk.
>>
>> I've tried doing "nodetool -h localhost repair system" and other nodetoo=
l
>> commands to try to compact the SSTables involved with it, but it never w=
ants
>> to let go of that slowly growing space.
>>
>> The Cassandra node in question is in a ring of size 1.
>>
>> Other than clobbering my data directory, how do I get my space back? =A0=
Is
>> it natural for this to grow seemingly infinitely (even though it's prett=
y
>> small increments), or did I find a bug?
>>
>> The reason I ask is I need to run unit tests in a shared developer
>> infrastructure with Cassandra, and we were having a little trouble with
>> TRUNCATE on column families, but that might have been environmental (I'v=
e
>> not looked deeply into it).
>>
>> Which is less expensive? =A0Create/Drop, or Truncate? =A0I don't expect
>> Truncate to swell the Migration Column Family because it tracks (seeming=
ly)
>> schema changes.
>>
>> Dave
>>
>>
>