| From: | Masahiko Sawada <masahiko(dot)sawada(at)2ndquadrant(dot)com> |
|---|---|
| To: | Fujii Masao <masao(dot)fujii(at)oss(dot)nttdata(dot)com> |
| Cc: | Masahiro Ikeda <ikedamsh(at)oss(dot)nttdata(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>, Muhammad Usama <m(dot)usama(at)gmail(dot)com>, amul sul <sulamul(at)gmail(dot)com>, Kyotaro Horiguchi <horikyota(dot)ntt(at)gmail(dot)com>, Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com>, Álvaro Herrera <alvherre(at)2ndquadrant(dot)com>, Thomas Munro <thomas(dot)munro(at)gmail(dot)com>, Ildar Musin <ildar(at)adjust(dot)com>, Kyotaro HORIGUCHI <horiguchi(dot)kyotaro(at)lab(dot)ntt(dot)co(dot)jp>, Chris Travers <chris(dot)travers(at)adjust(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com>, "Tsunakawa, Takayuki" <tsunakawa(dot)takay(at)jp(dot)fujitsu(dot)com>, Tatsuo Ishii <ishii(at)sraoss(dot)co(dot)jp> |
| Subject: | Re: Transactions involving multiple postgres foreign servers, take 2 |
| Date: | 2020-07-16 05:47:10 |
| Message-ID: | CA+fd4k7f-+YfHbv9SOWCQhb8ZVietZdRX+=DaVA9JjJwNtETiw@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Tue, 14 Jul 2020 at 11:19, Fujii Masao <masao(dot)fujii(at)oss(dot)nttdata(dot)com> wrote:
>
>
>
> On 2020/07/14 9:08, Masahiro Ikeda wrote:
> >> I've attached the latest version patches. I've incorporated the review
> >> comments I got so far and improved locking strategy.
> >
> > Thanks for updating the patch!
>
> +1
> I'm interested in these patches and now studying them. While checking
> the behaviors of the patched PostgreSQL, I got three comments.
Thank you for testing this patch!
>
> 1. We can access to the foreign table even during recovery in the HEAD.
> But in the patched version, when I did that, I got the following error.
> Is this intentional?
>
> ERROR: cannot assign TransactionIds during recovery
No, it should be fixed. I'm going to fix this by not collecting
participants for atomic commit during recovery.
>
> 2. With the patch, when INSERT/UPDATE/DELETE are executed both in
> local and remote servers, 2PC is executed at the commit phase. But
> when write SQL (e.g., TRUNCATE) except INSERT/UPDATE/DELETE are
> executed in local and INSERT/UPDATE/DELETE are executed in remote,
> 2PC is NOT executed. Is this safe?
Hmm, you're right. I think atomic commit must be used also when the
user executes other write SQLs such as TRUNCATE, COPY, CLUSTER, and
CREATE TABLE on the local node.
>
> 3. XACT_FLAGS_WROTENONTEMPREL is set when INSERT/UPDATE/DELETE
> are executed. But it's not reset even when those queries are canceled by
> ROLLBACK TO SAVEPOINT. This may cause unnecessary 2PC at the commit phase.
Will fix.
Regards,
--
Masahiko Sawada http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
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