On 08/15/2017 09:55 PM, Robert Haas wrote:
On Tue, Aug 15, 2017 at 3:42 PM, Tomas Vondra
<tomas.von...@2ndquadrant.com> wrote:
What I think we should not do is interpret the bitmasks (omitting some of
the information) assuming all the bits were set correctly.

I'm still confused. HEAP_XMIN_COMMITTED|HEAP_XMIN_ABORTED == HEAP_XMIN_FROZEN. Nobody is proposing to omit anything; to the contrary, what's being proposed is not to display the same thing
twice (and in a misleading fashion, to boot).


I understand your point. Assume you're looking at this bit of code:

    if (HeapTupleHeaderXminCommitted(enumval_tup->t_data))
        return;

which is essentially

    if (enumval_tup->t_data & HEAP_XMIN_COMMITTED)
        return;

If the function only gives you HEAP_XMIN_FROZEN, how likely is it you miss this actually evaluates as true?

You might say that people investigating issues in this area of code should be aware of how HEAP_XMIN_FROZEN is defined, and perhaps you're right ...

regards

--
Tomas Vondra                  http://www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services


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