| From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
|---|---|
| To: | "Tsunakawa, Takayuki" <tsunakawa(dot)takay(at)jp(dot)fujitsu(dot)com> |
| Cc: | Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com>, Ashutosh Bapat <ashutosh(dot)bapat(at)enterprisedb(dot)com>, Antonin Houska <ah(at)cybertec(dot)at>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: [HACKERS] Transactions involving multiple postgres foreign servers |
| Date: | 2018-01-09 14:38:20 |
| Message-ID: | CA+TgmoaQ6kTTzq4uNZV6MULNBa5ciP-LbxWb4P+_v4ChbwYn3w@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Wed, Dec 27, 2017 at 9:40 PM, Tsunakawa, Takayuki
<tsunakawa(dot)takay(at)jp(dot)fujitsu(dot)com> wrote:
> (1)
> Why don't you use the existing global variable MyXactFlags instead of the new TransactionDidWrite? Or, how about using XactLastRecEnd != 0 to determine the transaction did any writes? When the transaction only modified temporary tables on 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
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