Mailing-List: contact user-help@cassandra.apache.org; run by ezmlm
Precedence: bulk
Reply-To: user@cassandra.apache.org
Received-SPF: pass (athena.apache.org: local policy)
DomainKey-Signature: a=rsa-sha1; c=nofws; d=thelastpickle.com; h=content-type
	:mime-version:subject:from:in-reply-to:date
	:content-transfer-encoding:message-id:references:to; q=dns; s=
	thelastpickle.com; b=lB+S/L4vd33bYThUzNsjXSpKmrfQAsqlEcQBZDwyHap
	0u9+KGTGgrsJFTlaliKqHldCEGIveiGVf/URnHCKPbJ0ZXX1FDKHOs1xQ6mX3OYa
	bNmDD6N9W1uSuRt8ji37HBk0hLRFmfZwFO73tNZKG/fOuh/CV2oRzdl7Md+4HwHo
	=
Content-Type: text/plain; charset=iso-8859-1
Mime-Version: 1.0 (Apple Message framework v1244.3)
Subject: Re: Tuning a column family for archival
From: aaron morton <aaron@thelastpickle.com>
In-Reply-To: 
 <CA+OgoCtcE7634mex82b=QNKz3Nc32=fQbjb5dTMUXZ5-Arc23A@mail.gmail.com>
Date: Thu, 11 Aug 2011 16:07:14 +1200
Content-Transfer-Encoding: quoted-printable
Message-Id: <17576A61-7748-46E8-8DDE-2F52B7EC2C8E@thelastpickle.com>
References: 
 <CA+OgoCtcE7634mex82b=QNKz3Nc32=fQbjb5dTMUXZ5-Arc23A@mail.gmail.com>
To: user@cassandra.apache.org

There's not much to do other than turn off the caches (which you have =
done) and leave it alone.=20

If you want to poke around perhaps look at the compaction settings (from =
CLI help):

- max_compaction_threshold: The maximum number of SSTables allowed =
before a
minor compaction is forced. Default is 32, setting to 0 disables minor
compactions.

Decreasing this will cause minor compactions to start more frequently =
and
be less intensive. The min_compaction_threshold and =
max_compaction_threshold
boundaries are the number of tables Cassandra attempts to merge together =
at
once.

- min_compaction_threshold: The minimum number of SSTables needed
to start a minor compaction. Default is 4, setting to 0 disables minor
compactions.

Increasing this will cause minor compactions to start less frequently =
and
be more intensive. The min_compaction_threshold and =
max_compaction_threshold
boundaries are the number of tables Cassandra attempts to merge together =
at
once.=20

You *could* disable compaction and then manually compact at the best =
time. If you are not doing many updates I'd wait and see.=20

You could repair different CF's at different times. This would help with =
reducing the amount of data that is used to build the Merkle tree's, but =
there is a bug about streaming the differences that means extra data is =
streamed (can't remember the bug number now)

I'd wait to see if there is an issue first.=20

Cheers

-----------------
Aaron Morton
Freelance Cassandra Developer
@aaronmorton
http://www.thelastpickle.com

On 11 Aug 2011, at 13:18, Jason Baker wrote:

> I have a column family that I'm using to archive records.  They're =
mostly kept around for historical purposes.  Aside from that, they're =
mostly considered deleted.  It's probably going to be very rare that =
anyone reads from this table *ever*.  I don't really even write to it =
that much. =20
>=20
> Does anyone have advice for me as far as how (or if) I should tune =
this table with that in mind?  My concern is less speeding up access to =
this table than it is making sure that it doesn't impact the performance =
of any other column families in any way.
>=20
> Here's the data from nodetool cfstat (although this table was just =
created a few days ago):
>=20
> 		Column Family: ArchivedLinks
> 		SSTable count: 1
> 		Space used (live): 29580801
> 		Space used (total): 97838786
> 		Number of Keys (estimate): 93184
> 		Memtable Columns Count: 7497
> 		Memtable Data Size: 3223587
> 		Memtable Switch Count: 11
> 		Read Count: 0
> 		Read Latency: NaN ms.
> 		Write Count: 139091
> 		Write Latency: 0.007 ms.
> 		Pending Tasks: 0
> 		Key cache: disabled
> 		Row cache: disabled
> 		Compacted row minimum size: 259
> 		Compacted row maximum size: 372
> 		Compacted row mean size: 311