voltdb

I've been working on a project for over half a year now, building healthcare software from the ground up. When I joined up, MySQL had been chosen as the primary data store. A few months and many headaches later, we've begun to investigate alternative data stores that can offer the flexibility we need to record our critical and ever-changing healthcare data. We've looked at many NoSQL solutions; MongoDB drawing the most of our attention. Being able to store structured, embedded data would be a huge benefit. We've been scared off by reports of data loss/reliability issues, however. I've come

I read about Voltdb's command log . The command log records the transaction invocations instead of each row change as in a write-ahead log. By recording only the invocation, the command logs are kept to a bare minimum, limiting the impact the disk I/O will have on performance. Can anyone explain the database theory behind why Voltdb uses a command log and why the standard SQL databases such as Postgres, MySQL, SQLServer, Oracle use a write-ahead log? I think it is better to rephrase: Why does new distributed VoltDB use a command log over write-ahead log? Let's do an experiment and imagine you

转自： https://blog.csdn.net/ransom0512/article/details/50440316 http://www.360doc.com/content/16/0712/11/9200790_574921580.shtml https://www.cnblogs.com/kkyycom/p/9359090.html VoltDB数据库是一个分布式，可扩展，shared-nothing的内存数据库。使用JAVA 写的存储过程来定义事务。使用标准SQL访问数据，使用并行的单线程处理方式确保数据一致性，同时避免了传统数据库的锁，插销，资源管理开销。 VoltDB具有如下特点： 高吞吐量：百万次每秒 横向拓展：可以根据需求自由拓展，性能线性增长。 高可用性：数据支持副本、也可以持久化保存、除此之外，还支持双活机制。 实时数据分析：数据实时性高，因为都是内存计算。 完整ACID支持，保证事务性和可靠性。 VoltDB的设计动机来源于内存成本的大幅下降，系统对于数据的时效性要求越来越高，而传统数据库由于数据在本地文件保存，所以不论并发还是处理速度，都难以满足要求。而新型的NoSQL数据库，又缺乏SQL支持以及完整的ACID的支持，完全无法提单传统数据库。 VoltDB、NoSQL和传统关系型数据库的对比如下所示： 适用场景 VoltDB适合OLTP系统