Re: Hot standby writable? - Mailing list pgsql-admin

From MichaelDBA
Subject Re: Hot standby writable?
Date
Msg-id 4612593a-e411-d95d-15a1-96576d89b22d@sqlexec.com
Whole thread Raw
In response to Hot standby writable?  (Les <nagylzs@gmail.com>)
Responses Re: Hot standby writable?  (Les <nagylzs@gmail.com>)
List pgsql-admin
Before executing the write command through Dbeaver, run this query first:
select pg_is_in_recovery()


Les wrote on 4/28/2022 5:52 AM:
Hello,

I have a cluster with a streaming replication primary, and two hot standbys (PostgreSQL 12.8). Today I connected to one of the standbys, and accidentally executed a CREATE TABLE statement. To my surprise, it created the table, and the change was visible on the primary and also on both standbys. I examined this behaviour, and found the following. If I connect to the standby using psql cli then the database is read-only, as expected:

test=> create table test(id int8 not null primary key);
ERROR:  cannot execute CREATE TABLE in a read-only transaction

But if I connect to the standby using dbeaver, then somehow the database becomes writable. Dbeaver runs on my computer, the standby runs on a separate network and the connection is established through an ssh tunnel. The primary instance is located inside another network (actually in a different datacenter), and it is behind a VPN. In other words, it is technically impossible for dbeaver to connect to the primary. And yet somehow it can make changes in the database.

Am I missing something? Is there a possibility that the hot standby forwards SQL statements to the primary? I was not aware of such functionality.

Right now, it imposes a security risk in our environment, so I would really like to know how this works.

Thanks,

   Laszlo



Regards,

Michael Vitale

Michaeldba@sqlexec.com

703-600-9343 


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