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Date: Tue, 3 Apr 2012 18:14:27 -0700
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 <CAJJ04x56xdOdMSwkvhbuyUW_YPZJyJhQAWth9LJOW8eFvJc-3Q@mail.gmail.com>
Subject: Re: System keyspace leak?
From: David Leimbach <leimy2k@gmail.com>
To: user <user@cassandra.apache.org>
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Well I just found this:

http://wiki.apache.org/cassandra/LiveSchemaUpdates

which explains a ton...  It looks like this particular Column Family will
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 make
VERY wide row.

That tells me enough to say "don't do that!"  :-)

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.  It'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 nodetool
> commands to try to compact the SSTables involved with it, but it never
> wants 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?  Is
> it natural for this to grow seemingly infinitely (even though it's pretty
> 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've
> not looked deeply into it).
>
> Which is less expensive?  Create/Drop, or Truncate?  I don't expect
> Truncate to swell the Migration Column Family because it tracks (seemingly)
> schema changes.
>
> Dave
>
>
>

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Well I just found this:<div><br></div><div><a href=3D"http://wiki.apache.or=
g/cassandra/LiveSchemaUpdates">http://wiki.apache.org/cassandra/LiveSchemaU=
pdates</a></div><div><br></div><div>which explains a ton... =A0It looks lik=
e this particular Column Family will grow infinitely (it&#39;s just one row=
 with a column per migration), so if I&#39;m pounding on my Cassandra node =
with CREATE/DROP activity, I&#39;m going to make VERY wide row.</div>
<div><br></div><div>That tells me enough to say &quot;don&#39;t do that!&qu=
ot; =A0:-)</div><div><br></div><div>Dave</div><div><br><div class=3D"gmail_=
quote">On Tue, Apr 3, 2012 at 6:00 PM, David Leimbach <span dir=3D"ltr">&lt=
;<a href=3D"mailto:leimy2k@gmail.com">leimy2k@gmail.com</a>&gt;</span> wrot=
e:<br>
<blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1p=
x #ccc solid;padding-left:1ex">I&#39;ve been trying to understand the overh=
ead of create/drop keyspace on Cassandra 1.0.8. =A0It&#39;s not free, espec=
ially when I&#39;ve managed to drive up the LiveDiskSpaceUsed for the Migra=
tions CF in the &quot;system&quot; keyspace up to over 12 MB of disk.<div>

<br></div><div>I&#39;ve tried doing &quot;nodetool -h localhost repair syst=
em&quot; and other nodetool commands to try to compact the SSTables involve=
d with it, but it never wants to let go of that slowly growing space.</div>

<div><br></div><div>The Cassandra node in question is in a ring of size 1.<=
/div><div><br></div><div>Other than clobbering my data directory, how do I =
get my space back? =A0Is it natural for this to grow seemingly infinitely (=
even though it&#39;s pretty small increments), or did I find a bug?</div>

<div><br></div><div>The reason I ask is I need to run unit tests in a share=
d developer infrastructure with Cassandra, and we were having a little trou=
ble with TRUNCATE on column families, but that might have been environmenta=
l (I&#39;ve not looked deeply into it).</div>

<div><br></div><div>Which is less expensive? =A0Create/Drop, or Truncate? =
=A0I don&#39;t expect Truncate to swell the Migration Column Family because=
 it tracks (seemingly) schema changes.</div><div><br></div><div>Dave</div><=
div>

<br></div><div><br></div>
</blockquote></div><br></div>

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