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From Dmitry Olshansky <dmitry.olshan...@gridnine.com>
Subject Re: Cassandra as storage for cache data
Date Tue, 02 Jul 2013 14:11:06 GMT
In our case we have continuous flow of data to be cached. Every second 
we're receiving tens of PUT requests. Every request has 500Kb payload in 
average and TTL about 20 minutes.

On the other side we have the similar flow of GET requests. Every GET 
request is transformed to "get by key" query for cassandra.

This is very simple and straightforward solution:
- one CF
- one key that is directly corresponds to cache entry key
- one value of type bytes that corresponds to cache entry payload

To be honest, I don't see how we can switch this solution to multi-CF 
scheme playing with time-based snapshots.

Today this solution crashed again with overload symptoms:
- almost non-stop compactifications on every node in cluster
- large io-wait in the system
- clients start failing with timeout exceptions

At the same time we see that cassandra uses only half of java heap. How 
we can enforce it to start using all available resources (namely 
operating memory)?

Best regards,
Dmitry Olshansky

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