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Date: Fri, 20 May 2011 16:32:14 +0800
From: Dikang Gu <dikang85@gmail.com>
To: user@cassandra.apache.org
Message-ID: <70375285F34F4630B4B700D818015913@gmail.com>
In-Reply-To: <BANLkTin+H4daw=hifeEg7nzKoW_rVXivbA@mail.gmail.com>
References: <39D6788E2320442ABAC9F4FCDCE6D8B4@gmail.com>
 <BANLkTin+H4daw=hifeEg7nzKoW_rVXivbA@mail.gmail.com>
Subject: Re: How to reduce the Read Latency.
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I use the default consistency level in the hector client, so it should be QUORUM.

-- 
Dikang Gu
0086 - 18611140205
On Friday, May 20, 2011 at 4:25 PM, Jeffrey Kesselman wrote: 
> What consistency are you asking for?
> 
> On Fri, May 20, 2011 at 7:42 AM, Dikang Gu <dikang85@gmail.com> wrote:
> > Hi All,
> > I'm running three cassandra 0.7.4 nodes in a cluster, and I give 2G memory
> > to each node.
> > Now, I get the cfstats here:
> > Keyspace: UserMap
> > Read Count: 38411
> > Read Latency: 123.54214613001484 ms.
> > Write Count: 44155
> > Write Latency: 0.02341093873853471 ms.
> > Pending Tasks: 0
> > Column Family: Map
> > SSTable count: 3
> > Space used (live): 32704387
> > Space used (total): 32704387
> > Memtable Columns Count: 49
> > Memtable Data Size: 3348
> > Memtable Switch Count: 56
> > Read Count: 38411
> > Read Latency: 123.542 ms.
> > Write Count: 44155
> > Write Latency: 0.023 ms.
> > Pending Tasks: 0
> > Key cache capacity: 200000
> > Key cache size: 611
> > Key cache hit rate: 0.9294361241314483
> > Row cache: disabled
> > Compacted row minimum size: 125
> > Compacted row maximum size: 17436917
> > Compacted row mean size: 147647
> > You can find that the Read Latency is really high here, so what can I do to
> > reduce the latency? Give more memory to the three nodes? Any other options?
> > Thanks.
> > --
> > Dikang Gu
> > 0086 - 18611140205
> 
> 
> 
> -- 
> It's always darkest just before you are eaten by a grue.
> 

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<div>
            <div>
                <span>I use the default consistency level in the hector c=
lient, so it should be QUORUM.<br>
                </span>
                <span><br>--&nbsp;<br>Dikang Gu<br>0086 - 18611140205<br>=
</span>
               =20
                <=21-- <p style=3D=22color: =23a0a0a0;=22>On =46riday, Ma=
y 20, 2011 at 4:25 PM, Jeffrey Kesselman wrote:</p> -->
                <p style=3D=22color: =23a0a0a0;=22>On =46riday, May 20, 2=
011 at 4:25 PM, Jeffrey Kesselman wrote:</p>
                <blockquote type=3D=22cite=22 style=3D=22border-left-styl=
e:solid;border-width:1px;margin-left:0px;padding-left:10px;=22>
                    <span><div><div>What consistency are you asking for=3F=
<br><br>On =46ri, May 20, 2011 at 7:42 AM, Dikang Gu &lt;<a href=3D=22mai=
lto:dikang85=40gmail.com=22>dikang85=40gmail.com</a>&gt; wrote:<br><block=
quote type=3D=22cite=22><div>Hi All,<br>I'm running three cassandra 0.7.4=
 nodes in a cluster, and I give 2G memory<br>to each node.<br>Now, I get =
the cfstats here:<br>Keyspace: UserMap<br>Read Count: 38411<br>Read Laten=
cy: 123.54214613001484 ms.<br>Write Count: 44155<br>Write Latency: 0.0234=
1093873853471 ms.<br>Pending Tasks: 0<br>Column =46amily: Map<br>SSTable =
count: 3<br>Space used (live): 32704387<br>Space used (total): 32704387<b=
r>Memtable Columns Count: 49<br>Memtable Data Size: 3348<br>Memtable Swit=
ch Count: 56<br>Read Count: 38411<br>Read Latency: 123.542 ms.<br>Write C=
ount: 44155<br>Write Latency: 0.023 ms.<br>Pending Tasks: 0<br>Key cache =
capacity: 200000<br>Key cache size: 611<br>Key cache hit rate: 0.92943612=
41314483<br>Row cache: disabled<br>Compacted row minimum size: 125<br>Com=
pacted row maximum size: 17436917<br>Compacted row mean size: 147647<br>Y=
ou can find that the Read Latency is really high here, so what can I do t=
o<br>reduce the latency=3F &nbsp;Give more memory to the three nodes=3F A=
ny other options=3F<br>Thanks.<br>--<br>Dikang Gu<br>0086 - 18611140205<b=
r></div></blockquote><br><br><br>-- <br>It's always darkest just before y=
ou are eaten by a grue.<br></div></div></span>
               =20
               =20
               =20
               =20
                </blockquote>
               =20
                <div>
                    <br>
                </div>
            </div>
        </div>
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