Return-Path: X-Original-To: apmail-cassandra-user-archive@www.apache.org Delivered-To: apmail-cassandra-user-archive@www.apache.org Received: from mail.apache.org (hermes.apache.org [140.211.11.3]) by minotaur.apache.org (Postfix) with SMTP id 947BB9C36 for ; Fri, 9 Mar 2012 18:08:55 +0000 (UTC) Received: (qmail 83099 invoked by uid 500); 9 Mar 2012 18:08:53 -0000 Delivered-To: apmail-cassandra-user-archive@cassandra.apache.org Received: (qmail 83065 invoked by uid 500); 9 Mar 2012 18:08:53 -0000 Mailing-List: contact user-help@cassandra.apache.org; run by ezmlm Precedence: bulk List-Help: List-Unsubscribe: List-Post: List-Id: Reply-To: user@cassandra.apache.org Delivered-To: mailing list user@cassandra.apache.org Received: (qmail 83056 invoked by uid 99); 9 Mar 2012 18:08:53 -0000 Received: from nike.apache.org (HELO nike.apache.org) (192.87.106.230) by apache.org (qpsmtpd/0.29) with ESMTP; Fri, 09 Mar 2012 18:08:53 +0000 X-ASF-Spam-Status: No, hits=2.2 required=5.0 tests=HTML_MESSAGE,RCVD_IN_DNSWL_NONE,SPF_PASS X-Spam-Check-By: apache.org Received-SPF: pass (nike.apache.org: local policy) Received: from [208.113.200.5] (HELO homiemail-a58.g.dreamhost.com) (208.113.200.5) by apache.org (qpsmtpd/0.29) with ESMTP; Fri, 09 Mar 2012 18:08:45 +0000 Received: from homiemail-a58.g.dreamhost.com (localhost [127.0.0.1]) by homiemail-a58.g.dreamhost.com (Postfix) with ESMTP id C303C7D806A for ; Fri, 9 Mar 2012 10:08:15 -0800 (PST) DomainKey-Signature: a=rsa-sha1; c=nofws; d=thelastpickle.com; h=from :mime-version:content-type:subject:date:in-reply-to:to :references:message-id; q=dns; s=thelastpickle.com; b=Qu1BOjK7Tj +632O/gpwxwycM1JAS/D9dk3G88AbmQVbD3T0PawfEf3nLqt8BNerfIHTUpJu/WC +SDUF7+jWPq5OokY7VdbLSlCk8Gi79c4oOq3RUlnlP+cvgKPql1DfQSE8CrE9KvQ ng8IHMUMAE9BvcsF8Nh3J4fbEFduo/fIM= DKIM-Signature: v=1; a=rsa-sha1; c=relaxed; d=thelastpickle.com; h=from :mime-version:content-type:subject:date:in-reply-to:to :references:message-id; s=thelastpickle.com; bh=NqMBWvxdTEKh292d 64jsYCy//fE=; b=BC3w+EOJPkAhoW17g/oXahdE+IxPR5aPKjGv1ggaCmbhGGba bPEkdgKCFCMplNXbjcdAsqzqR+/VpZLPdYt0hUX1vFaIfmx9fQPGf6dv9e3NUD25 bUF68r7kBwa0dbXG5KhWNVJEZpI488MeszvLUn/cqKaTaWimmXlyai/wTXw= Received: from [172.16.1.3] (125-236-193-159.adsl.xtra.co.nz [125.236.193.159]) (using TLSv1 with cipher AES128-SHA (128/128 bits)) (No client certificate requested) (Authenticated sender: aaron@thelastpickle.com) by homiemail-a58.g.dreamhost.com (Postfix) with ESMTPSA id D9F2C7D8060 for ; Fri, 9 Mar 2012 10:08:14 -0800 (PST) From: aaron morton Mime-Version: 1.0 (Apple Message framework v1257) Content-Type: multipart/alternative; boundary="Apple-Mail=_7E7CC0B4-B68A-4BAD-85D9-9AA01EB2E5D4" Subject: Re: Single column read latency Date: Sat, 10 Mar 2012 07:08:11 +1300 In-Reply-To: To: user@cassandra.apache.org References: Message-Id: <4D92DF06-45CB-4B89-81B5-5990774D448D@thelastpickle.com> X-Mailer: Apple Mail (2.1257) X-Virus-Checked: Checked by ClamAV on apache.org --Apple-Mail=_7E7CC0B4-B68A-4BAD-85D9-9AA01EB2E5D4 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=iso-8859-1 Check the latency on the server, use nodetool cfstats. Call it before = the request to recent the "recent" latency. Then dive into nodetool cfhistogram to see how much effort went into = retrieving the request. Cheers ----------------- Aaron Morton Freelance Developer @aaronmorton http://www.thelastpickle.com On 9/03/2012, at 9:38 AM, A J wrote: > Hello, > In a CF I have with valueless columns and column-name type being > integer, I am seeing latency in the order of 80-90ms to retrieve a > single column from a row containing 50K columns. It is just a single > node db on a single box. > Another row with 20K columns in the same CF, still has the latency > around 30ms to get to a single column. >=20 > Example in pycassa, for a row with 50K columns: > t1 =3D time.time() > cf1.get(5011,columns=3D[90006111]) > t2 =3D time.time() - t1 > print int(t2*1000),'ms' >=20 > gives 82 ms >=20 > Any idea what could be causing the latency to be so high ? That too > after ensuring that the row_cache is large enough to contain all the > rows and all the rows are pre-fetched. >=20 > Thanks. --Apple-Mail=_7E7CC0B4-B68A-4BAD-85D9-9AA01EB2E5D4 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=iso-8859-1 Check = the latency on the server, use nodetool cfstats. Call it before the = request to recent the "recent" latency.

Then dive = into nodetool cfhistogram to see how much effort went into retrieving = the request.

Cheers

http://www.thelastpickle.com

On 9/03/2012, at 9:38 AM, A J wrote:

Hello,
In a CF I have with valueless columns and = column-name type being
integer, I am seeing latency in the order of = 80-90ms to retrieve a
single column from a row containing 50K = columns. It is just a single
node db on a single box.
Another row = with 20K columns in the same CF, still has the latency
around 30ms to = get to a single column.

Example in pycassa, for a row with 50K = columns:
t1 =3D time.time()
cf1.get(5011,columns=3D[90006111])
t2= =3D time.time() - t1
print  int(t2*1000),'ms'

gives 82 = ms

Any idea what could be causing the latency to be so high ? = That too
after ensuring that the row_cache is large enough to contain = all the
rows and all the rows are = pre-fetched.

Thanks.

<= /html>= --Apple-Mail=_7E7CC0B4-B68A-4BAD-85D9-9AA01EB2E5D4--