public inbox for pgsql-novice@postgresql.org
help / color / mirror / Atom feedFrom: Subramanian,Ramachandran <ramachandran.subramanian@alte-leipziger.de>
To: Laurenz Albe <laurenz.albe@cybertec.at>
To: pgsql-novice@lists.postgresql.org <pgsql-novice@lists.postgresql.org>
Subject: AW: Replication Testing- How to introduce a Lag
Date: Tue, 24 Mar 2026 07:51:57 +0000
Message-ID: <39ec6185a893473aa9217520e5a92be7@alte-leipziger.de> (raw)
In-Reply-To: <013104103e016e84d59c1e2accb0b1b1f99d9870.camel@cybertec.at>
References: <aadb9058660d4e10b5cee44b82458802@alte-leipziger.de>
<f3927bc3a9baf4400325b91652869907f0581c97.camel@cybertec.at>
<e1e41761323040228570cf6a7e02518e@alte-leipziger.de>
<8b38fa5141905f9ad6983b8d5ae944e812e3d28a.camel@cybertec.at>
<fa47fe18078043adbdfe007b7270ffd0@alte-leipziger.de>
<fc42f77c80fdb3c0267148b807edfacc49b0b0ca.camel@cybertec.at>
<fc3be1f56ded49dc9be519f92d8b9ab4@alte-leipziger.de>
<0e00fcc0062b59b88f98dba4900ce49d5a9a3fea.camel@cybertec.at>
<477369bf897b44feb2d2368f6fca93fc@alte-leipziger.de>
<89d63402747edb3bf80ff668fdd63cc77334f446.camel@cybertec.at>
<aa307627991c41f280bb6da27ebc9b1d@alte-leipziger.de>
<013104103e016e84d59c1e2accb0b1b1f99d9870.camel@cybertec.at>
Thank you for your reply. I am grateful for your knowledge.
My aim is to be able to see
1. Is replication caught up --> No problems here
2. If not caught up , what is the LSN difference --> No problems here , you have already helped me
3. If not caught up, how many bytes / KB worth of data needs to be replicated
So far my replication runs like a dream, I am just preparing for when we transfer our mainframe tables to Postgres and I should be able to answer such questions.
I am just preparing myself.
LG
Ram
Freundliche Grüße
i. A. Ramachandran Subramanian
Zentralbereich Informationstechnologie
Alte Leipziger Lebensversicherung a.G.
Hallesche Krankenversicherung a.G.
Alte Leipziger Lebensversicherung a.G., Alte Leipziger-Platz 1, 61440 Oberursel
Vors. des Aufsichtsrats: Dr. Walter Botermann · Vorstand: Christoph Bohn (Vors.), Dr. Jürgen Bierbaum (stv. Vors.), Frank Kettnaker, Dr. Jochen Kriegmeier, Alexander Mayer, Christian Pape, Wiltrud Pekarek, Udo Wilcsek
Sitz Oberursel (Taunus) · Rechtsform VVaG · Amtsgericht Bad Homburg v. d. H. HRB 1583 · USt.-IdNr. DE 114106814
Hallesche Krankenversicherung a.G., Löffelstraße 34-38, 70597 Stuttgart
Vors. des Aufsichtsrats: Dr. Walter Botermann · Vorstand: Christoph Bohn (Vors.), Dr. Jürgen Bierbaum (stv. Vors.), Frank Kettnaker, Dr. Jochen Kriegmeier, Alexander Mayer, Christian Pape,
Wiltrud Pekarek, Udo Wilcsek
Sitz Stuttgart · Rechtsform VVaG · Amtsgericht Stuttgart HRB 2686 · USt.-IdNr. DE 147802285
Beiträge zu privaten Kranken- und Pflegekrankenversicherungen unterliegen nicht der Versicherungsteuer (§ 4 Nr. 5 VersStG) · Versicherungsleistungen sowie Umsätze aus Versicherungsvertreter-/Maklertätigkeiten sind umsatzsteuerfrei
Die Pflichtangaben der ALH Gruppe gemäß § 35a GmbHG bzw. § 80 AktG finden Sie hier: https://www.alte-leipziger.de/impressum
______________________
ALH Gruppe
Alte Leipziger-Platz 1, 61440 Oberursel
Tel.: +49 (6171) 66-4882
Fax: +49 (6171) 66-800-4882
E-Mail: ramachandran.subramanian@alte-leipziger.de
www.alte-leipziger.de
www.hallesche.de
-----Ursprüngliche Nachricht-----
Von: Laurenz Albe <laurenz.albe@cybertec.at>
Gesendet: Dienstag, 24. März 2026 08:07
An: Subramanian,Ramachandran IT-md-db <ramachandran.subramanian@alte-leipziger.de>; pgsql-novice@lists.postgresql.org
Betreff: Re: Replication Testing- How to introduce a Lag
On Tue, 2026-03-24 at 06:14 +0000, Subramanian,Ramachandran wrote:
> I noticed that if I insert one row in a table at the source, the
> difference in LSNs is not 1 . ( with a delibrately introduced delay
> on the apply side ),
>
> It is sometimes 96, sometimes 296 ( for the same table two inserts ) .
Right, because the LSN is not a counter that increases with each new WAL record. It is a position in the WAL stream. The difference between the LSNs of two adjacent WAL records is not 1, but the byte count of the first WAL record.
For example: if you insert a larger row, the LSN will advance more.
Note also that not all inserts will produce the same kind of WAL:
one insert might write a full page image to the WAL, while the next a normal insert record.
> Is there a method to calculate the APPROXIMATE amount of data in (
> Bytes ) that are yet to be transfered from Source to Standby ?
That's exactly what pg_wal_lsn_diff() does.
What is your worry? What is your ultimate goal?
Yours,
Laurenz Albe
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: ramachandran.subramanian@alte-leipziger.de, laurenz.albe@cybertec.at, pgsql-novice@lists.postgresql.org
Subject: Re: AW: Replication Testing- How to introduce a Lag
In-Reply-To: <39ec6185a893473aa9217520e5a92be7@alte-leipziger.de>
* 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