I’m not sure that’s it either. PostgreSQL has a feature — don’t remember what it’s called — where multiple readers can share a serial table scan.

Suppose client A runs “select * from foo”, which has a thousand records. It can start streaming those results starting with row 1. Now suppose it’s on row 500 when client B runs the same query. Instead of starting over for B, it can start streaming results to B starting at row 501. Each time it reads a row, now it sends that to both clients.

Now when it finishes with row 1000, client A’s query is done. It starts back over with B on row 1 and continues through row 500.

Hypothetically, you can serve N clients with a total of 2 table scans if they all arrive before the first client’s scan is finished.

So that’s the kind of magic where I think this is going to shine. Queue up a few queries and it’s likely that several will be able to share the same underlying work.