"Jim C. Nasby" <jnasby@xxxxxxxxxxxxx> writes: > On Sat, Sep 24, 2005 at 07:19:10PM -0400, Tom Lane wrote: >> Currently, when a tuple is reclaimed by VACUUM, we just mark its item >> pointer as unused (and hence recyclable). I think it might be safe to >> decrease pd_lower if there are unused pointers at the end of the page's >> pointer array, but we don't currently do that. > Sounds like a good newbie TODO? Uh, no, because the $64 question is whether it actually *is* safe, or perhaps would be safe with more locking than we do now. I'm not sure of the answer myself, and would have zero confidence in a newbie's answer. Decreasing pd_lower would definitely be a win if we can do it free or cheaply. If it requires significant additional locking overhead, then maybe not. regards, tom lane ---------------------------(end of broadcast)--------------------------- TIP 2: Don't 'kill -9' the postmaster
