Scalability comparison between different DBMSs

By what factor does the performance (read queries/sec) increase when a machine is added to a cluster of machines running either:

• a Bigtable-l开发者_JS百科ike database
• MySQL?

Google's research paper on Bigtable suggests that "near-linear" scaling is achieved can be achieved with Bigtable. This page here featuring MySQL's marketing jargon suggests that MySQL is capable of scaling linearly.

Where is the truth?

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Having built and benchmarked several applications using VoltDB I consistently measure between 90% and 95% of additional transactional throughput as each new server is added to the cluster. So if an application is performing 100,000 transaction per second (TPS) on a single server, I measure 190,000 TPS on 2 servers, 280,000 TPS on 3 servers, and so on. At some point we expect the server to server networking to become a bottleneck but our largest cluster (30 servers) is still above 90%.

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If you don't do that many writes to the database, MySQL may be a good and easy solution, especially if coupled with memcached in order to increase the read speed.

OTOH if you data is constantly changing, you should probably look somewhere else:

• Cassandra
• VoltDB
• Riak
• MongoDB
• CouchDB
• HBase

These systems have been designed to scale linearly with the number of computers added to the system. A full list is available here.