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From: Stephen Frost <sfrost@snowman.net>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Andres Freund <andres@anarazel.de>
Cc: Dilip Kumar <dilipbalaut@gmail.com>
Cc: pgsql-hackers@postgresql.org <pgsql-hackers@postgresql.org>
Subject: Re: .ready and .done files considered harmful
Date: Wed, 5 May 2021 16:53:01 -0400
Message-ID: <20210505205301.GK20766@tamriel.snowman.net> (raw)
In-Reply-To: <CA+TgmoYxD6TLbEUMnyorRFdJ8EdV8z9MCOV9qLPJr_pAqwtw9g@mail.gmail.com>
References: <20210504042755.ehuaoz5blcnjw5yk@alap3.anarazel.de>
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	<CA+TgmoYxD6TLbEUMnyorRFdJ8EdV8z9MCOV9qLPJr_pAqwtw9g@mail.gmail.com>

Greetings,

* Robert Haas (robertmhaas@gmail.com) wrote:
> On Wed, May 5, 2021 at 4:31 PM Andres Freund <andres@anarazel.de> wrote:
> > On 2021-05-05 16:22:21 -0400, Robert Haas wrote:
> > > Huh, I had not thought about that problem. So, at the risk of getting
> > > sidetracked, what exactly are you asking for here? Let the extension
> > > pick the timeline using an algorithm of its own devising, rather than
> > > having core do it? Or what?
> >
> > Not Stephen, but to me the most reasonable way to address this is to
> > make timeline identifier wider and randomly allocated. The sequential
> > looking natures of timelines imo is actively unhelpful.
> 
> Yeah, I always wondered why we didn't assign them randomly.

Based on what we do today regarding the info we put into .history files,
trying to figure out which is the "latest" timeline might be a bit
tricky with randomly selected timelines.  Maybe we could find a way to
solve that though.

I do note that this comment is timeline.c is, ahem, perhaps over-stating
things a bit:

 * Note: while this is somewhat heuristic, it does positively guarantee
 * that (result + 1) is not a known timeline, and therefore it should
 * be safe to assign that ID to a new timeline.

Thanks,

Stephen

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