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Date: Mon, 22 Nov 2010 17:30:47 -0800
Message-ID: <AANLkTimik7JMHS9baW9uUDp-4hW_wuZ040C31iN2o=O3@mail.gmail.com>
Subject: Re: cassandra vs hbase summary (was facebook messaging)
From: David Jeske <davidj@gmail.com>
To: user@cassandra.apache.org
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> My point still applies though. Caching HFIle blocks on a single node
>> vs individual "dataums" on N nodes may not be more efficient. Thus
>> terms like "Slower" and "Less Efficient" could be very misleading.
>>
>
I seem to have missed this the first time around. Next time I correct the
summary I'll include something about the subtlties of block vs record
caching. If you access sparse/random rows, and rows are small, the record
caching on multiple machines may in fact be more efficicent than block
caching on fewer machines.

That said, the story for pinning ranges of data in memory doesn't seem to
change.

Another interesting difference has to do with scan vs seek performance.
There was one comment about cassandra possibly having better seek
performance than hbase because of some hdfs slowness, which was then rumored
to be in the works to fix. Anyone have any other comments about scan or seek
performance comparisons?

Again, I understand Cassandra is not HBase. However, it's useful to be able
to compare them (and their designs), so people can understand what might
help them choose one over the other.  Thanks again!

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<div class=3D"gmail_quote"><br><blockquote class=3D"gmail_quote" style=3D"m=
argin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;"><div class=
=3D"im"><div class=3D"gmail_quote"><blockquote class=3D"gmail_quote" style=
=3D"margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
My point still applies though. Caching HFIle blocks on a single node<br>
vs individual &quot;dataums&quot; on N nodes may not be more efficient. Thu=
s<br>
terms like &quot;Slower&quot; and &quot;Less Efficient&quot; could be very =
misleading.<br></blockquote></div></div></blockquote><div><br></div><div>I =
seem to have missed this the first time around. Next time I correct the sum=
mary I&#39;ll include something about the subtlties of block vs record cach=
ing. If you access sparse/random rows, and rows are small, the record cachi=
ng on multiple machines may in fact be more efficicent than block caching o=
n fewer machines.=A0</div>
<div><br></div><div>That said, the story for pinning ranges of data in memo=
ry doesn&#39;t seem to change.</div><div><br></div><div>Another interesting=
 difference has to do with scan vs seek performance. There was one comment =
about cassandra possibly having better seek performance than hbase because =
of some hdfs slowness, which was then rumored to be in the works to fix. An=
yone have any other comments about scan or seek performance comparisons?=A0=
</div>
<div><br>Again, I understand Cassandra is not HBase. However, it&#39;s usef=
ul to be able to compare them (and their designs), so people can understand=
 what might help them choose one over the other. =A0Thanks again!</div></di=
v>

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