From: Laurenz Albe <laurenz.albe@cybertec.at>
To: h@husseinnasser.com
To: pgsql-docs@lists.postgresql.org
Subject: Re: Transaction wraparound and read committed isolation level
Date: Tue, 21 Feb 2023 10:51:42 +0100
Message-ID: <56d92102952fff2283f05b8d7712e34bad4647e4.camel@cybertec.at> (raw)
In-Reply-To: <167677624368.647177.14087162303276367700@wrigleys.postgresql.org>
References: <167677624368.647177.14087162303276367700@wrigleys.postgresql.org>
On Sun, 2023-02-19 at 03:10 +0000, PG Doc comments form wrote:
> The following documentation comment has been logged on the website:
>
> Page: https://www.postgresql.org/docs/15/routine-vacuuming.html
> Description:
>
> hey guys
>
> thanks for the work you do we really appreciate it.
>
> In the transaction wraparound section this statement is misleading and got
> me really confused.
>
> “a row version with an insertion XID greater than the current transaction's
> XID is “in the future” and should not be visible to the current
> transaction“
>
> If the current transaction isolation level is read committed it absolutely
> can see rows committed by future transactions with higher XIDs.
You are right, in combination with PlanQualEval you can.
> Would be cool to add a note.
>
> this also bear the question that the wraparound isn’t really a problem with
> default isolation level but more for higher levels such as repeatable read
> and such.
>
> please correct me if my understanding is incorrect.
Wraparound can be a problem on all isolation levels. It has to do with
transaction IDs and visibility.
Yours,
Laurenz Albe
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To: pgsql-docs@postgresql.org
Cc: laurenz.albe@cybertec.at, h@husseinnasser.com, pgsql-docs@lists.postgresql.org
Subject: Re: Transaction wraparound and read committed isolation level
In-Reply-To: <56d92102952fff2283f05b8d7712e34bad4647e4.camel@cybertec.at>
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