Date: Fri, 05 Aug 2022 11:49:16 +0900 (JST)
Message-Id: <20220805.114916.994654810780821553.horikyota.ntt@gmail.com>
To: laurenz.albe@cybertec.at
Cc: bharath.rupireddyforpostgres@gmail.com,
 pgsql-hackers@lists.postgresql.org, satyanarlapuram@gmail.com
Subject: Re: An attempt to avoid
 locally-committed-but-not-replicated-to-standby-transactions in
 synchronous replication
From: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
In-Reply-To: <9290b55b6ae2b04e002ca9dadadd1cca09461482.camel@cybertec.at>
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At Tue, 26 Apr 2022 08:26:59 +0200, Laurenz Albe <laurenz.albe@cybertec.at> wrote in 
> While this may mitigate the problem, I don't think it will deal with
> all the cases which could cause a transaction to end up committed locally,
> but not on the synchronous standby.  I think that only using the full
> power of two-phase commit can make this bulletproof.
> 
> Is it worth adding additional complexity that is not a complete solution?

I would agree to this. Likewise 2PC, whatever we do to make it
perfect, we're left with unresolvable problems at least for now.

Doesn't it meet your requirements if we have a means to know the last
transaction on the current session is locally committed or aborted?

We are already internally managing last committed LSN. I think we can
do the same thing about transaction abort and last inserted LSN and we
can expose them any way. This is way simpler than the (maybe)
uncompletable attempt to fill up the deep gap.

regards.

-- 
Kyotaro Horiguchi
NTT Open Source Software Center