Re: [HACKERS] [PATCH] pageinspect function to decode infomasks

On Tue, Aug 15, 2017 at 10:59 PM, Tomas Vondra
<tomas.vondra@2ndquadrant.com> wrote:
>
>
> On 08/15/2017 03:24 PM, Robert Haas wrote:
>>
>> On Mon, Aug 14, 2017 at 9:59 PM, Craig Ringer <craig@2ndquadrant.com>
>> wrote:
>>>
>>> The bits are set, those macros just test to exclude the special meaning
>>> of
>>> both bits being set at once to mean "frozen".
>>>
>>> I was reluctant to filter out  HEAP_XMIN_COMMITTED and HEAP_XMIN_INVALID
>>> when we detect that it's frozen, because that could well be misleading
>>> when
>>> debugging.
>>
>>
>> I don't think so -- the "committed" and "invalid" meanings are
>> effectively canceled when the "frozen" mask is present.
>>
>> I mean, "committed" and "invalid" contradict each other...
>>
>
> FWIW I agree with Craig - the functions should output the masks raw, without
> any filtering. The reason is that when you're investigating data corruption
> or unexpected behavior, all this is very useful when reasoning about what
> might (not) have happened.
>
> Or at least make the filtering optional.
>

I'd vote for having both and making one optional (perhaps filtering?).
Both are useful to me for the debugging and study purpose.

Regards,

--
Masahiko Sawada
NIPPON TELEGRAPH AND TELEPHONE CORPORATION
NTT Open Source Software Center