On Wed, Apr 11, 2018 at 2:34 AM, Chapman Flack <c...@anastigmatix.net> wrote:
> On 04/10/2018 04:03 PM, Robert Haas wrote:
>> I suspect you want, or maybe need, to use the same snapshot as the
>> scan that retrieved the tuple containing the toasted datum.
> I'm sure it's worth more than that, but I don't know if it's
> implementable.
> If I'm a function, and the datum came to me as a parameter, I may
> have no way to determine what snapshot the enclosing query used to
> obtain the thing passed to me.

Before query execution, we push the active snapshot, so any time
during execution, if you get the active snapshot via
GetActiveSnapshot(), you can access it.  So, I think during a function
execution, if you use GetActiveSnapshot, you should get the snapshot
used by enclosing query.

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

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