[grammr]

I'm Derek, one of the co-founders--great questions!

> So you create a table, insert into it, and it's always empty. Is that right?

That is correct. Streams can only be read by continuous queries (e.g. you can't even run a SELECT on them).

> Does this work for any table in pg? How does pg know that the insert should NOT actually insert a row?

PipelineDB streams are represented as a specific kind of PostgreSQL foreign table [0], so only foreign tables created in a specific way will be considered streams. You can use triggers to write table rows and updates out to streams if you want to though.

[0] https://www.postgresql.org/docs/current/static/sql-createfor...