public inbox for pgsql-novice@postgresql.org  
help / color / mirror / Atom feed
From: Laurenz Albe <laurenz.albe@cybertec.at>
To: Subramanian,Ramachandran <ramachandran.subramanian@alte-leipziger.de>
To: pgsql-novice@lists.postgresql.org <pgsql-novice@lists.postgresql.org>
Subject: Re: AW: how long should Archive logs be retained
Date: Fri, 28 Nov 2025 08:10:49 +0100
Message-ID: <882aecb90795236e37a354d986d4ccebf8ad9c4c.camel@cybertec.at> (raw)
In-Reply-To: <070dbb3e6b4f41c39e41f5f2979ee4a9@alte-leipziger.de>
References: <a02ba9c8a1c046d292766096eecd2631@alte-leipziger.de>
	<1f12660d233efc644edb6a23c7bd4bcc84b503af.camel@cybertec.at>
	<329482d836f34a548d071aab63961f11@alte-leipziger.de>
	<d615d389a140169a5d338cf540a0c17ed3ec346e.camel@cybertec.at>
	<070dbb3e6b4f41c39e41f5f2979ee4a9@alte-leipziger.de>

On Fri, 2025-11-28 at 04:46 +0000, Subramanian,Ramachandran wrote:
> Question >>>  Wow !!  That is so new to me.  So
> 1. if log wrap around happens  and some Wal-Files containing uncomitted log records are being overwritten,

No, they are deleted (well, perhaps recycled, but that amounts to the same).

> 2. AND  iin the mean time some data updates pertaining to these uncomitted transactions have been flushed from the data buffers to disk
> 3. AND after the data buffers have been flushed the transaction fails ( and I assume releases all the locks ) 
> 
> how does postgres know that  a particular unlocked row it finds in the disk ( or even the bufferpool
> for that matter ) is not in a valid state  even though it physically exists in the table?
> How can it decode this information?



reply

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Reply to all the recipients using the --to and --cc options:
  reply via email

  To: pgsql-novice@postgresql.org
  Cc: laurenz.albe@cybertec.at, ramachandran.subramanian@alte-leipziger.de, pgsql-novice@lists.postgresql.org
  Subject: Re: AW: how long should Archive logs be retained
  In-Reply-To: <882aecb90795236e37a354d986d4ccebf8ad9c4c.camel@cybertec.at>

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

This inbox is served by agora; see mirroring instructions
for how to clone and mirror all data and code used for this inbox