David Rowley <dgrowleyml(at)gmail(dot)com> writes:
> However, maybe you've left it this way as you feel it's a decision
> that must be made in the future, perhaps based on how difficult it
> would be to free up another bit?
Yeah, pretty much. I think it'll be a long time before we run out
of memory context IDs, and it's hard to anticipate the tradeoffs
that will matter at that time.
regards, tom lane