Re: Question about behavior of snapshot too old feature

From: Kevin Grittner <kgrittn(at)gmail(dot)com>
To: Bruce Momjian <bruce(at)momjian(dot)us>
Cc: Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com>, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Question about behavior of snapshot too old feature
Date: 2016-10-19 16:15:38
Message-ID: CACjxUsMVF3cuRi9eyO6TxNyB=Ba0t5Y+EwrGFSK=-BU2jkbuFg@mail.gmail.com
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On Wed, Oct 19, 2016 at 11:11 AM, Bruce Momjian <bruce(at)momjian(dot)us> wrote:
> On Wed, Oct 19, 2016 at 11:08:28AM -0500, Kevin Grittner wrote:
>> On Wed, Oct 19, 2016 at 10:04 AM, Bruce Momjian <bruce(at)momjian(dot)us> wrote:
>>
>>> Slide 10 of this presentation has an example showing
>>> old_snapshot_threshold set to '1min':
>>>
>>> http://momjian.us/main/writings/pgsql/features.pdf
>>
>> If the presentation is intending to show reasonable values for
>> production use, that would be better as, maybe, '2h'.

> The example is just to illustrate the activities required to trigger it,
> e.g. pg_sleep(), VACUUM.

Yeah, in such a demonstration you probably don't want to have
everyone sit for 2 hours, so 1 minute makes perfect sense. :-)

--
Kevin Grittner
EDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

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