The key thing about the performance aspect is SQL produces bi-modal behavior due to there being a query planner / operator execution. If all of a sudden your pe

The key thing about the performance aspect is SQL produces bi-modal behavior due to there being a query planner / operator execution. If all of a sudden your performance characteristics change dramatically because the query planner produced a different result than normal due to something changing about your dataset, that could be pretty bad. So, not having this risk of bi-modal behavior is a nice feature of dedicated pub/sub and queue software.