Re: Proposal: GetOldestXminExtend for ignoring arbitrary vacuum flags

From: Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>
To: "Seki, Eiji" <seki(dot)eiji(at)jp(dot)fujitsu(dot)com>
Cc: "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Proposal: GetOldestXminExtend for ignoring arbitrary vacuum flags
Date: 2017-02-14 09:48:39
Message-ID: CAA4eK1JWSDeviTnOXvmoQrFXQ9nAGt55cs7Zy3tbopFUGKMCqw@mail.gmail.com
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On Tue, Feb 14, 2017 at 11:49 AM, Seki, Eiji <seki(dot)eiji(at)jp(dot)fujitsu(dot)com> wrote:
> Hi all,
>
> I propose the patch that adds a function GetOldestXminExtended that is like GetOldestXmin but can ignore arbitrary vacuum flags. And then, rewrite GetOldestXmin to use it. Note that this is done so as not to change the behavior of GetOldestXmin.
>
> This change will be useful for features that only reads rows that are visible by all transactions and could not wait specific processes (VACUUM, ANALYZE, etc...) for performance.
>

How will you decide just based on oldest xmin whether the tuple is
visible or not? How will you take decisions about tuples which have
xmax set?

--
With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com

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