Re: Reviewing freeze map code

On Fri, Jul 1, 2016 at 10:22 AM, Masahiko Sawada <sawada.mshk@gmail.com> wrote:
> Ah, you're right, I misunderstood.
>
> Attached updated patch incorporating your comments.
> I've changed it so that heap_xlog_lock clears vm flags if page is
> marked all frozen.

I believe that this should be separated into two patches, since there
are two issues here:

1. Locking a tuple doesn't clear the all-frozen bit, but needs to do so.
2. heap_update releases the buffer content lock without logging the
changes it has made.

With respect to #1, there is no need to clear the all-visible bit,
only the all-frozen bit.  However, that's a bit tricky given that we
removed PD_ALL_FROZEN.  Should we think about putting that back again?Should we just clear all-visible and call it good
enough? The only
 
cost of that is that vacuum will come along and mark the page
all-visible again instead of skipping it, but that's probably not an
enormous expense in most cases.

-- 
Robert Haas
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