That's awesome! If you don't mind - one more q.. I see that stream-stream joins are not yet supported (http://docs.pipelinedb.com/joins.html#stream-stream-joins). Can you comment on when you think this feature cold land or is it still a ways off?
The primary issue in implementing stream-stream JOINs is that we'd essentially need to preemptively store every single raw event that could be matched on at some point in the future. Conceptually this is straightforward, but on a technical level we just haven't seen the demand to optimize for it.
That being said, you could just use a regular table as one of the "streams" you wanted to JOIN on and then use an stream-table JOIN. As long as the table side of the JOIN is indexed on the JOIN condition, an STJ would probably be performant enough for a lot of use cases. With PostgreSQL's increasingly excellent partitioning support this is becoming especially practical.
I also suspect that this is an area where integration with TimescaleDB could be really interesting!