Re: Error "initial slot snapshot too large" in create replication slot

From: Kyotaro Horiguchi <horikyota(dot)ntt(at)gmail(dot)com>
To: dilipbalaut(at)gmail(dot)com
Cc: andres(at)anarazel(dot)de, jchampion(at)timescale(dot)com, y(dot)sokolov(at)postgrespro(dot)ru, rjuju123(at)gmail(dot)com, pgsql-hackers(at)lists(dot)postgresql(dot)org
Subject: Re: Error "initial slot snapshot too large" in create replication slot
Date: 2022-09-13 07:10:59
Message-ID: 20220913.161059.331955937797746838.horikyota.ntt@gmail.com
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At Tue, 13 Sep 2022 12:08:18 +0530, Dilip Kumar <dilipbalaut(at)gmail(dot)com> wrote in
> On Tue, Sep 13, 2022 at 11:52 AM Kyotaro Horiguchi
> <horikyota(dot)ntt(at)gmail(dot)com> wrote:
> > That function is called after the SnapBuild reaches
> > SNAPBUILD_CONSISTENT state ,or SnapBuildInitialSnapshot() rejects
> > other than that state. That is, IIUC the top-sub relationship of all
> > the currently running transactions is fully known to reorder buffer.
> > We need a comment about that.
>
> I don't think this assumption is true, any xid started after switching
> to the SNAPBUILD_FULL_SNAPSHOT and before switching to the
> SNAPBUILD_CONSISTENT, might still be in progress so we can not
> identify whether they are subxact or not from reorder buffer.

Yeah, I misunderstood that the relationship is recorded earlier
(how?). Thus it is not reliable in the first place.

I agree that the best way is oversized xip.

By the way, I feel that "is >= than" is redundant or plain wrong..

regards.

--
Kyotaro Horiguchi
NTT Open Source Software Center

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