Return-Path: Delivered-To: apmail-cassandra-user-archive@www.apache.org Received: (qmail 91793 invoked from network); 1 Apr 2010 20:37:16 -0000 Received: from unknown (HELO mail.apache.org) (140.211.11.3) by 140.211.11.9 with SMTP; 1 Apr 2010 20:37:16 -0000 Received: (qmail 93450 invoked by uid 500); 1 Apr 2010 20:37:16 -0000 Delivered-To: apmail-cassandra-user-archive@cassandra.apache.org Received: (qmail 93429 invoked by uid 500); 1 Apr 2010 20:37:16 -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 93402 invoked by uid 99); 1 Apr 2010 20:37:16 -0000 Received: from athena.apache.org (HELO athena.apache.org) (140.211.11.136) by apache.org (qpsmtpd/0.29) with ESMTP; Thu, 01 Apr 2010 20:37:15 +0000 X-ASF-Spam-Status: No, hits=2.2 required=10.0 tests=FREEMAIL_FROM,HTML_MESSAGE,RCVD_IN_DNSWL_NONE,SPF_PASS,T_TO_NO_BRKTS_FREEMAIL X-Spam-Check-By: apache.org Received-SPF: pass (athena.apache.org: domain of jamesgolick@gmail.com designates 209.85.223.185 as permitted sender) Received: from [209.85.223.185] (HELO mail-iw0-f185.google.com) (209.85.223.185) by apache.org (qpsmtpd/0.29) with ESMTP; Thu, 01 Apr 2010 20:37:09 +0000 Received: by iwn15 with SMTP id 15so1045456iwn.7 for ; Thu, 01 Apr 2010 13:36:49 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:received:in-reply-to:references :date:received:message-id:subject:from:to:content-type; bh=oY10Gxn8yifLShV8bwbiAQx80el52dFnh0O3R4cO9P4=; b=tLDI4eoxWVl9dFMRGx4TVFen0ivW2NDFEo1zl5ihLKKluPAcQTAzCUdC8E472GTGx0 mVgWdi9KKqVMcqiJQyCavZXnoFe72cLcPpBk1jpEq4N3xLVShpTsRXWYlHZlPxMpNKIT sbPKxjGN5s8s08Af24WC/ttSgK5sAoLFOtERc= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type; b=OPZU8Dyzo51FtGhG2eEvpXr3tD/1KiEIQiHG10FkTOGjGeorFcbIoHuTKNb8IC9c3C Megg8ofSsoZe7uqW03d6OhtJuQ1ghyUFZ7P+rQMpLrPDT+SS4HpCjG59iszAzYPP1avL rMU7re8Vx6y8v/FtVbK6gL0+5PKyjwp7Db8XM= MIME-Version: 1.0 Received: by 10.231.113.234 with HTTP; Thu, 1 Apr 2010 13:36:48 -0700 (PDT) In-Reply-To: References: <1ab2da821003302047h128aaed9g1a65f3972836b086@mail.gmail.com> <1270060358.18338.3.camel@barium> Date: Thu, 1 Apr 2010 13:36:48 -0700 Received: by 10.231.60.19 with SMTP id n19mr387508ibh.79.1270154209067; Thu, 01 Apr 2010 13:36:49 -0700 (PDT) Message-ID: Subject: Re: Read Performance From: James Golick To: user@cassandra.apache.org Content-Type: multipart/alternative; boundary=001485e76dfe713ef3048332d2d7 --001485e76dfe713ef3048332d2d7 Content-Type: text/plain; charset=ISO-8859-1 I don't have the additional hardware to try to isolate this issue atm, so I decided to push some code that performs 20% of reads directly from cassandra. The cache hit rate has gone up to about 88% now and it's still climbing, albeit slowly. There remains plenty of free cache space. So far, the average time to multi_get those 20 rows is still hovering around 35-45ms. I'll report back with more info as it comes in. On Thu, Apr 1, 2010 at 12:06 AM, Cemal Dalar wrote: > Hi James, > > I don't know how to get the below statistics data and calculate the access > times (read/write in ms) in your previous mails. Can you explain a little? > Iike to work on it also. > > CD > > > On Thu, Apr 1, 2010 at 4:15 AM, Jonathan Ellis wrote: > >> On Wed, Mar 31, 2010 at 6:21 PM, James Golick >> wrote: >> > Keyspace: ActivityFeed >> > Read Count: 699443 >> > Read Latency: 16.11017477192566 ms. >> >> > Column Family: Events >> > Read Count: 232378 >> > Read Latency: 0.396 ms. >> > Row cache capacity: 500000 >> > Row cache size: 62768 >> > Row cache hit rate: 0.007716049382716049 >> >> This says that >> >> - recent queries to Events are much faster than the lifetime average >> for your Keyspace >> - even though you have almost no row cache hits (~1700 out of 232000 >> reads) >> >> Not sure what to make of that, tbh. If it were me I would try to >> reproduce on a test machine w/o all that pesky live traffic confusing >> things. >> >> -Jonathan >> > > --001485e76dfe713ef3048332d2d7 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable I don't have the additional hardware to try to isolate this issue atm, = so I decided to push some code that performs 20% of reads directly from cas= sandra. The cache hit rate has gone up to about 88% now and it's still = climbing, albeit slowly. There remains plenty of free cache space.

So far, the average time to multi_get those 20 rows is still= hovering around 35-45ms.

I'll report back wit= h more info as it comes in.

On Thu, Apr 1= , 2010 at 12:06 AM, Cemal Dalar <cemal.dalar@gmail.com> wrote:
Hi James,=A0

= I don't know how to get the below statistics data and calculate the acc= ess times (read/write in ms) in your previous mails. Can you explain a litt= le? Iike to work on it also.=A0

CD


On Thu, Apr 1, 2010 at 4:15 = AM, Jonathan Ellis <jbellis@gmail.com> wrote:
On Wed, Mar 31, 2010 at 6:21 PM, James Golick <jamesgolick@gmail.com> wrote:=
> Keyspace: ActivityFeed
> =A0=A0 =A0 =A0 =A0Read Count: 699443
> =A0=A0 =A0 =A0 =A0Read Latency: 16.11017477192566 ms.

> =A0=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0Column Family: Events
> =A0=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0Read Count: 232378
> =A0=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0Read Latency: 0.396 ms.
> =A0=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0Row cache capacity: 50000= 0
> =A0=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0Row cache size: 62768
> =A0=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0Row cache hit rate: 0.00771604938271= 6049

This says that

=A0- recent queries to Events are much faster than the lifetime average
for your Keyspace
=A0- even though you have almost no row cache hits (~1700 out of 232000 rea= ds)

Not sure what to make of that, tbh. =A0If it were me I would try to
reproduce on a test machine w/o all that pesky live traffic confusing
things.

-Jonathan


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