The main difference between PipelineDB and old CEP frameworks is that PipelineDB is based on the PostgreSQL 9.4 core, so is a fully functional relational database in addition to a streaming processing engine, which gives us integrated storage in addition to a SQL-based approach to stream processing and realtime/streaming analytics. We have also added functionality like probabilistic data structures, stream-table joins for adding historical context to streams, and now offer a distributed architecture, realtime alerting, and HA. So there is definitely some overlap with the types of things CEP frameworks did, but having an open-source core based on PostgreSQL that operates with 100% SQL enables a wider range of users to deal with an increasing need to tackle realtime data challenges.
