Re: [HACKERS] [PROPOSAL] Use SnapshotAny in get_actual_variable_range

On Fri, May 5, 2017 at 1:28 PM, Dmitriy Sarafannikov
<dsarafannikov@yandex.ru> wrote:
> Amit, thanks for comments!
>
>> 1.
>> +#define InitNonVacuumableSnapshot(snapshotdata)  \
>> + do { \
>> + (snapshotdata).satisfies = HeapTupleSatisfiesNonVacuumable; \
>> + (snapshotdata).xmin = RecentGlobalDataXmin; \
>> + } while(0)
>> +
>>
>> Can you explain and add comments why you think RecentGlobalDataXmin is
>> the right to use it here?  As of now, it seems to be only used for
>> pruning non-catalog tables.
>
> Can you explain me, what value for xmin should be used there?
>

I think we can use RecentGlobalDataXmin for non-catalog relations and
RecentGlobalXmin for catalog relations (probably a check similar to
what we have in heap_page_prune_opt).


-- 
With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com