Re: [HACKERS] PG10 transition tables, wCTEs and multiple operationson the same table

On Wed, Jun 7, 2017 at 3:42 AM, Thomas Munro
<thomas.munro@enterprisedb.com> wrote:
> On Wed, Jun 7, 2017 at 7:27 PM, Thomas Munro
> <thomas.munro@enterprisedb.com> wrote:
>> On Wed, Jun 7, 2017 at 10:47 AM, Peter Geoghegan <pg@bowt.ie> wrote:
>>> I suppose you'll need two tuplestores for the ON CONFLICT DO UPDATE
>>> case -- one for updated tuples, and the other for inserted tuples.
>>
>> Hmm.  Right.  INSERT ... ON CONFLICT DO UPDATE causes both AFTER
>> INSERT and AFTER UPDATE statement-level triggers to be fired, but then
>> both kinds see all the tuples -- those that were inserted and those
>> that were updated.  That's not right.
>
> Or maybe it is right.

The idea of transition tables is that you see all changes to the
target of a single statement in the form of delta relations -- with
and "old" table for any rows affected by a delete or update and a
"new" table for any rows affected by an update or delete.  If we
have a single statement that combines INSERT and UPDATE behaviors,
it might make sense to have an "old" table for updates and a single
"new" table for both.

--
Kevin Grittner
VMware vCenter Server
https://www.vmware.com/