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From "Bingbing Liu" <rucb...@gmail.com>
Subject wo did some test on cassandra ,but the result puzzled us
Date Fri, 12 Mar 2010 05:36:10 GMT
We did some test on on Cassandra, and the benchmark is from Section 7 of the BigTable paper
“Bigtable: A Distributed Storage System for Structured Data”, the benchmark task includes:
random write, random read, sequential write, and sequential read. The test results made us
puzzled. We use a cluster of 5 nodes (each node has a 4 cores cpu , 4G memory).The data for
test is a table with 4,000,000  records each of which is 1000 bytes. The test results are
as follows:
Sequential write:  875124 ms
Sequential read:  1972588 ms
Random read:  43331738 ms
Random write:  20193484 ms
We wondered why the speed of sequential write are so faster than the speed of sequential read,
and why the speed of sequential write are so faster than that of random write? We think that
the speed of read should be faster than that of data write, but the results are just the opposite,
would you please give us some explanations, thanks a lot!

2010-03-12 



Bingbing Liu 
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