From: "Wong, Yi Wen" <yiwong@amazon.com>
To: Alvaro Herrera <alvherre@alvh.no-ip.org>,
        Michael Paquier
	<michael.paquier@gmail.com>
CC: Peter Geoghegan <pg@bowt.ie>, "Wood, Dan" <hexpert@amazon.com>,
        "pgsql-bugs@postgresql.org" <pgsql-bugs@postgresql.org>,
        Andres Freund
	<andres@anarazel.de>
Subject: Re: Old row version in hot chain become visible after a freeze
Thread-Topic: [BUGS] Old row version in hot chain become visible after a
 freeze
Thread-Index: AQHTJ3fzEH9T5bMCDUufad1KxDA7S6Kvvd+AgAEpfwCAAAoegIAAp59AgAAqJpA=
Date: Tue, 12 Sep 2017 20:54:58 +0000
Message-ID: <1505249698051.58904@amazon.com>
References: 
 <CAB7nPqTc0-imDj-5URYW9a5A+yijFv_UUXucDE=3TLyUmZg3AA@mail.gmail.com>,<20170912082203.gq5hutuveqlxpvuc@alvherre.pgsql>,<1505241452245.71279@amazon.com>
In-Reply-To: <1505241452245.71279@amazon.com>
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> > > I also tweaked lazy_record_dead_tuple to fail with ERROR if the tuple
> > > cannot be recorded, as observed by Yi Wen.  AFAICS that's not reachab=
le
> > > because of the way the array is allocated, so an elog(ERROR) is
> > > sufficient.
>
> I agree the fail is rare (and probably doesn't happen in real cases, alth=
ough the comment
> does imply with a sufficiently low working_memory it might?). However, I'=
d dispute that ERROR
> is sufficient --PANIC is probably appropriate here because FREEZE is not =
WAL-logged until
> the end of the page; so we'd end up with unfrozen Xids hanging around wit=
h an appropriately
> timed crash. I wouldn't worry much about the PANIC tripping because like =
you said,
> this seems unreachable normally.
>=20
> The errmsg should come with a errhint saying "Increase maintenance_work_m=
em".

On closer inspection, I misread the code. The freezes are collected instead=
 of executed, so a ERROR would
suffice. We don't need to change it to PANIC. errhint comment remains.

Yi Wen

--=20
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