Re: Fwd: Avoid endless futile table locks in vacuuming.

Jeff Janes <jeff(dot)janes(at)gmail(dot)com> writes:
> On Dec 29, 2015 4:47 PM, "Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> Uh, isn't that what my patch is doing?

> My reading was it does that only if there are no tuples that could be
> frozen. If there are tuples that could be frozen, it actually does
> the freezing, even though that is not necessary unless scan_all is
> true.

Ah, now I see.

> So like the attached, although it is a bit weird to call
> lazy_check_needs_freeze if , under !scan_all, we don't actually care
> about whether it needs freezing but only the hastup.

True, but this is such a corner case that it doesn't seem worth expending
additional code to have a special-purpose page scan for it.

regards, tom lane