Andres>I think the biggestoverhead here is that the executor startup includes Andres>too many indirect (linked lists) datastructured, that allocated each Andres>round
The case is very common: batch inserts are popular in Java, and ORMs use batch API automatically.
However, there's high per-backend-message overhead, and that overhead is very noticeable.
CTE doc>Trying to update the same row twice in a single statement is not supported. Only one of the modifications takes place, but it is not easy (and sometimes not possible) to reliably predict which one
