hibernate
Update: A very nice JavaWorld podcast interview with Google engineer Max Ross on Hibernate Shards. Max defines Hibernate Shards (horizontal partitioning), how it works (pretty well), virtual shards (don't ask), what they need to do in the future (query, replication, operational tools), and how it relates to Google
General Discussion
Let me begin by saying that I have used and continue to use various ORM frameworks such as hibernate, ibatis, propel and activerecord in applications and websites that have a user base ranging from a couple hundred to 500k users. Especially for projects that have to be up and running
General Discussion
In The Architectures You've Always Wondered About track at the Qcon conference, Second Life, eBay, Yahoo, LinkedIn and Orbitz presented how they dealt with different aspects of their applications, such as scalability. There were quite a few lessons that I learned that day that I thought were worth
Example
Fotolog, a social blogging site centered around photos, grew from about 300 thousand users in 2004 to over 11 million users in 2007. Though they initially experienced the inevitable pains of rapid growth, they overcame their problems and now manage over 300 million photos and 800,000 new photos are
Product
If you want to adopt a shard architecture, but don't want to start from scratch, you may want to consider Hibernate's sharding system. Hibernate Shards is a framework that is designed to encapsulate and minimize this complexity by adding support for horizontal partitioning to Hibernate Core.