Key points

1) No stored procedures are used. There are some very simple triggers.
2) Move cpu-intensive work moved out of the database layer to applications applications layer: referential integrity, joins, sorting done in the application layer! Reasoning: app servers are cheap, databases are the bottleneck.
3) No client-side transactions. no distributed transactions
4) J2EE: use servlets, JDBC, connection pools (with rewrite). Not much else.
5) No state information in application tier. Transient state maintained in cookie or scratch database.

http://highscalability.com/ebay-architecture

How ebay use Cassandra - http://www.infoq.com/cn/articles/best-practice-of-cassandra-data-model-design http://www.infoq.com/cn/articles/best-practices-cassandra-data-model-design-part2 http://www.ebaytechblog.com/2012/07/16/cassandra-data-modeling-best-practices-part-1/ http://www.ebaytechblog.com/2012/08/14/cassandra-data-modeling-best-practices-part-2/