Date: Tue, 17 Jul 2018 09:01:29 +0900
From: Michael Paquier <michael@paquier.xyz>
To: Heikki Linnakangas <hlinnaka@iki.fi>
Cc: Robert Haas <robertmhaas@gmail.com>,
	Andrew Dunstan <andrew.dunstan@2ndquadrant.com>,
	"pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>
Subject: Re: [HACKERS] WAL logging problem in 9.4.3?
Message-ID: <20180717000129.GA3388@paquier.xyz>
References: <20180105041040.GI2416@tamriel.snowman.net>
 <20180111.170355.123986255.horiguchi.kyotaro@lab.ntt.co.jp>
 <20180330.100646.86008470.horiguchi.kyotaro@lab.ntt.co.jp>
 <20180704045912.GG1672@paquier.xyz>
 <df32e286-ae2b-f45a-8f2e-4fa02684300b@iki.fi>
 <20180711033241.GQ1661@paquier.xyz>
 <aac8e19b-9159-e473-77be-53f80b658190@2ndQuadrant.com>
 <08b11907-d0b2-c396-2978-ba5aac1972df@iki.fi>
 <CA+TgmoZGn7MmMGRu4NkfxyXKSCzmvq1JvqsWm=hN=GJDMTfTKg@mail.gmail.com>
 <026AD6A1-3396-47F4-B87E-77E3F139D166@iki.fi>
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On Mon, Jul 16, 2018 at 09:41:51PM +0300, Heikki Linnakangas wrote:
> On 16 July 2018 21:38:39 EEST, Robert Haas <robertmhaas@gmail.com> wrote:
>>On Thu, Jul 12, 2018 at 10:12 AM, Heikki Linnakangas <hlinnaka@iki.fi>
>>wrote:
>>> Doesn't have to be a trigger, could be a CHECK constraint, datatype
>>input
>>> function, etc. Admittedly, having a datatype input function that
>>inserts to
>>> the table is worth a "huh?", but I'm feeling very confident that we
>>can
>>> catch all such cases, and some of them might even be sensible.
>>
>>Is this sentence missing a "not"?  i.e. "I'm not feeling very
>>confident"?
>=20
> Yes, sorry.

This explains a lot :p

I doubt as well that we'd be able to catch all the holes as well as the
conditions where the optimization could be run safely are rather
basically impossible to catch beforehand.  I'd like to vote for getting
rid of this optimization for COPY, this can hurt more than it is
helpful.  Per the lack of complaints, this could happen only in HEAD?
--
Michael

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