From: Piotr Andreassen Blasiak <piotr@attendium.com>
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Subject: Logical replication slots on slaves/replicas?
Message-Id: <AB145716-132B-4BB5-AC69-32EA9FDE4633@attendium.com>
Date: Thu, 1 Aug 2024 10:42:20 +0200
To: pgsql-general@lists.postgresql.org
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Hi,

I know that currently logical replication slots are available only for =
primary servers. Is there any plan to add this feature to read slaves as =
well? My problem is this:

I want to use debezium to stream changes from postgresql. But, if I =
stream changes from the master I can not query my read slaves for =
related data to these changes - I need to always query the master which =
is not scalable. So either I need a way to be able to know when the =
change has been propagated to my read replica so that I can reliably =
query it, or I am hoping I can simply read all the changes from the read =
replica which will mean it is already up to date when I query it.

Piotr Andreassen Blasiak


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<html><head><meta http-equiv="content-type" content="text/html; charset=us-ascii"></head><body style="overflow-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;">Hi,<div><br></div><div>I know that currently logical replication slots are available only for primary servers. Is there any plan to add this feature to read slaves as well? My problem is this:</div><div><br></div><div>I want to use debezium to stream changes from postgresql. But, if I stream changes from the master I can not query my read slaves for related data to these changes - I need to always query the master which is not scalable. So either I need a way to be able to know when the change has been propagated to my read replica so that I can reliably query it, or I am hoping I can simply read all the changes from the read replica which will mean it is already up to date when I query it.<br><div>
<div dir="auto" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none; caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0); overflow-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;"><div><br class="Apple-interchange-newline">Piotr Andreassen Blasiak</div><div><br></div></div><br class="Apple-interchange-newline" style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;"><br class="Apple-interchange-newline">
</div>
<br></div></body></html>
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