Alex Bolenok <quassnoi(at)gmail(dot)com> writes:
> I get why it's not working (because the statement is not allowed to see the
> tuples with its own cmin), but I was wondering if it was worth it at least
> to spell it out explicitly in the documentation.
What's not explicit about this?
The sub-statements in WITH are executed concurrently with each other
and with the main query. Therefore, when using data-modifying
statements in WITH, the order in which the specified updates actually
happen is unpredictable. All the statements are executed with the same
snapshot (see Chapter 13), so they cannot “see” one another's effects
on the target tables.
regards, tom lane