Re: [HACKERS] Transactions involving multiple postgres foreign servers

On Wed, Dec 27, 2017 at 9:40 PM, Tsunakawa, Takayuki
<tsunakawa.takay@jp.fujitsu.com> wrote:
> (1)
> Why don't you use the existing global variable MyXactFlags instead of the new TransactionDidWrite?  Or, how about
usingXactLastRecEnd != 0 to determine the transaction did any writes?  When the transaction only modified temporary
tableson the local database and some data on one remote database, I think 2pc is unnecessary. 

If I understand correctly, XactLastRecEnd can be set by, for example,
a HOT cleanup record, so that doesn't seem like a good thing to use.
Whether we need to use 2PC across remote nodes seems like it shouldn't
depend on whether a local SELECT statement happened to do a HOT
cleanup or not.

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company