Re: Fwd: Avoid endless futile table locks in vacuuming. - Mailing list pgsql-hackers

From Tom Lane
Subject Re: Fwd: Avoid endless futile table locks in vacuuming.
Date
Msg-id 22168.1451503025@sss.pgh.pa.us
Whole thread Raw
In response to Fwd: Avoid endless futile table locks in vacuuming.  (Jeff Janes <jeff.janes@gmail.com>)
List pgsql-hackers
Jeff Janes <jeff.janes@gmail.com> writes:
> On Dec 29, 2015 4:47 PM, "Tom Lane" <tgl@sss.pgh.pa.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



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