Re: [COMMITTERS] pgsql-server: Rearrange pg_subtrans handling

> Uh ... the interesting question is usually not "does this backend hold
> any row locks", it is "is this row locked by any backends".  If the
> latter question is not *exceedingly* cheap to answer, at least in the
> normal case where the answer is no, you don't have a workable solution,
> because you'll be adding nontrivial overhead to every row update.

OK, what I mean is to know if a row is locked by any backend, why can't 
we just put a reference count of the number of locks on that row, 
instead of recording each backend separately?  Wouldn't that require a 
fixed amount of shared mem?

Chris