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From Markus Klems <markuskl...@gmail.com>
Subject Analysis of performance benchmarking - unexpected results
Date Wed, 15 Feb 2012 18:33:58 GMT
Hi Cassandra community,

we conducted performance benchmarking experiments on Cassandra 0.7 (on
EC2 instances) using YCSB++ and stumbled upon some unexpected results:

1. Changing consistency level configurations from Write.ALL + Read.ONE
to Write.ALL + Read.ALL increases write latency (expected) and
decrease read latency (unexpected).
2. Changing from a single-region Cassandra cluster to a multi-region
Cassandra cluster on EC2 significantly increases write latency (approx
2x, again expected) but slightly decreases read latency (approx -10%,
again unexpected).

The effects could be due to unexplained variance in our model (we
might have forgotten to include important independent variables),
however we got quite good "R-squared adjusted" and are therefore
somewhat confident that the results reflect some mechanism in
Cassandra. Do you have an explanation for the effect? It seems
counter-intuitive at first sight.

Thanks,

Markus

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