Gartner2013年10月21日发布了今年的四象限图，Oracle是老大，MS、IBM和SAP紧随其后，
- 主流是NoSQL系统，如MongoDB、DataStax、Couchbase、Basho（Riak）、MarkLogic、AeroSpike；
- 今年Gartner似乎喜欢内存数据库，因此SAP、Voltdb、Altibase、McObjects的评价都不错；
- 有几个NewSQL：包括NuoDB、Clustrix、VoltDB；
- 传统SQL数据库：Actian、EnterpriseDB
- 图数据库：OrientDB
- 对象数据库：Cache（InterSystems）
关注一下VoltDB：
VoltDB
Located in Boston, Massachusetts, U.S., VoltDB (www.voltdb.com) markets an in-memory row-store DBMS for the operational DBMS market. VoltDB (founded in 2008) is an open-source DBMS that is available as software only.
Strengths
- Technology and vision — The unique H-Store technology and IMDBMS allows VoltDB to reach extreme performance. Many customers are performing HTAP transactions and analytics in the same database, with high velocity data.
- Open-source — VoltDB is the only open-source IMDBMS vendor, positioning it uniquely in the market for customers desiring an open-source product.
- Performance and value — As expected of an IMDBMS, VoltDB received high reference scores on overall performance as well as on value for the price paid.
Cautions
- Revenue model — the open-source model is a double-edged sword: reducing the revenue of VoltDB; preventing it from growing at the speed of its competitors; and also restricting new feature delivery.
- Partnerships and reach — VoltDB is small, with few resources for its sales force. Although the ecosystem is growing, independent software vendors and partners remain low — further limiting its ability to reach new customers.
- Ease of use — VoltDB references called out ease of use as an issue, specifically missing SQL language elements that required workarounds for the applications.
相关信息：
http://www.gartner.com/technology/reprints.do?id=1-1M9YEHW&ct=131028&st=sb
https://www.gartner.com/doc/2610218
http://www.clustrix.com/free-trial/
http://en.wikipedia.org/wiki/NuoDB
http://www.infoq.com/cn/articles/nuodb-architecture-1