Re: 7.4 - FK constraint performance

Rod Taylor <rbt@rbt.ca> writes:
> Statistics say there are 10 values. Statistics list the 10 most common
> values (all of them). Given this, would it not be reasonable to assume
> that 239 is a recent addition (if there at all) to the table and not
> very common?

We don't know that it's 239 when we make the plan.  In order to know
that, we'd have to abandon caching of RI check query plans and re-plan
for each row.  That strikes me as inevitably a losing proposition.
        regards, tom lane