Analytics Gallery: 2010 Data Center Operational Trends Report
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NoSQL database system Cassandra recently launched the beta version its 0.7 feature improvement release with support for secondary indexes. The support makes it easier to analyze data found in a single column, such as finding a certain age grouping in a column of birth dates.

Cassandra is an open source project sponsored by the Apache Software Foundation to push forward the development of the key value store, NoSQL system. Jonathan Ellis, who founded the project while working for Rackspace, was the keynote speaker at the Cassandra Summit held at San Francisco's Mission Bay Conference Center Aug. 10. Current uses of Cassandra include Facebook, Digg, and Twitter, which stores 15 million tweets a day in Cassandra.

Ellis, in an interview, said the addition of secondary indexes to Cassandra makes it possible to index columns in the tables of the Cassandra database. Primary indexes, which are already supported, are based on rows in the database.

In addition, the 0.7 release includes support for rows that contain more than two GBs of data in Cassandra table; in the past two GBs was the limit for a row. The 0.7 release can also create families of columns while the database is running. Previously, a node needed to be shut down for a family to be generated from the data stored on it. A family can be queried and a response obtained more quickly than a query being required to review all the columns in the database, he said.

Ellis talked about the features of the 0.7 release in his address, The Present and Future of Cassandra. He was introduced by Bill Boebel, VP of strategy at Rackspace, who said Rackspace wished to contribute to open source projects that lead to more cloud computing software. As more users adopt the code, "we'll get a percentage of them" as cloud users in the company's cloud infrastructure offering. Rackspace is an investor in the company that Ellis co-founded, Riptano, to supply training and support. His partner was Matt Pfeil, also a former Rackspace employee.

Ellis said about 200 Cassandra users were at the summit. He asked attendees how many of them were using Cassandra in production systems and about a third indicated they were, he said. Boebel termed the Cassandra event "the biggest individual NoSQL event held thus far." MongoDB, a document-oriented, NoSQL system, held its own user conference in San Francisco May 3 with a similar number of attendees.

A non-scientific poll conducted by Hacker News among startup developers found the open source MySQL database system still the most popular choice for establishing a company database, followed by the PostgreSQL database project. On their heels came NoSQL systems, MongoDB, third, and CouchDB and Cassandra tied for sixth. Redis and Microsoft databases took the fourth and fifth place spots.