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From Robert Coli <>
Subject Re: cassandra performance problems
Date Thu, 05 Dec 2013 18:35:40 GMT
On Thu, Dec 5, 2013 at 4:33 AM, Alexander Shutyaev <>wrote:

> Cassandra version is 2.0.3. ... We've plugged it into our production
> environment as a cache in front of postgres.

> What can be the reason? Can it be high number of tables? Do we need to
> adjust some settings for this setup? Is it ok to have so many tables?
> Theoretically we can stuck them all in 3-4 tables.

500 column families ("tables") is "a lot" but not necessarily "too many."

During that time cluster read latency goes from 2ms to 200ms

In perfectly normal operation, things operating in the JVM may exhibit a
few hundreds of milliseconds of latency, when the JVM pauses for garbage
collection. If you absolutely require consistent latency below this time
for all requests, something running in the JVM may not be for you.

If compaction triggers "runaway GC" then you probably have too much steady
state heap consumption. You don't mention anything about the hardware
environment, how much heap is available, etc.. ?


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