Thread

set failover=true on existing logical replication slot PG18

Scot Kreienkamp <scot.kreienkamp@la-z-boy.com> — 2026-06-19T15:24:49Z

Hello list,

I am trying to make use of the synchronized logical replication slots on PG18. I have all the requirements met, and if I create a logical replication slot manually with failover=true it is replicated to the second node. Unfortunately I have two connections that create their own logical replication slots with failover false. AWS DMS is one for example, but both have the same problem. Is there any way to change the failover parameter on an existing logical replication slot from false to true? Or set it so that all logical replications slots are synchronized so that they don't have to be individually created or altered for replication=true? Or force them all to true? Any other ideas?

Thanks!

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Re: set failover=true on existing logical replication slot PG18

Matthew Tice <mjtice@gmail.com> — 2026-06-20T12:16:36Z

> On Jun 19, 2026, at 9:24 AM, Scot Kreienkamp <Scot.Kreienkamp@la-z-boy.com> wrote:
> 
> Hello list,
>  
> I am trying to make use of the synchronized logical replication slots on PG18.  I have all the requirements met, and if I create a logical replication slot manually with failover=true it is replicated to the second node.  Unfortunately I have two connections that create their own logical replication slots with failover false.  AWS DMS is one for example, but both have the same problem.  Is there any way to change the failover parameter on an existing logical replication slot from false to true?  Or set it so that all logical replications slots are synchronized so that they don’t have to be individually created or altered for replication=true?  Or force them all to true?  Any other ideas?
>  
> Thanks!
>  

I had the same problem recently with our Confluent-generated replication slots.  I didn’t think there was but I just found this in the docs:

ALTER_REPLICATION_SLOT slot_name ( option [, ...] ) 
Change the definition of a replication slot. See Section 26.2.6 for more about replication slots. This command is currently only supported for logical replication slots.

slot_name
The name of the slot to alter. Must be a valid replication slot name (see Section 26.2.6.1).

The following option is supported:

FAILOVER [ boolean ]
If true, the slot is enabled to be synced to the standbys so that logical replication can be resumed after failover.

https://www.postgresql.org/docs/17/protocol-replication.html
53.4. Streaming Replication Protocol
postgresql.org

RE: set failover=true on existing logical replication slot PG18

Hayato Kuroda (Fujitsu) <kuroda.hayato@fujitsu.com> — 2026-06-22T05:44:15Z

Dear Matthew, Scot,

There are no ways to control default value of failover. Regarding the way for
changing the value, yes, ALTER_REPLICATION_SLOT replication command is an only
way to do that. Note that it's acceptable only when the backend is in the
replication mode - normal backend cannot understand them.

Best regards,
Hayato Kuroda
FUJITSU LIMITED

RE: set failover=true on existing logical replication slot PG18

Scot Kreienkamp <scot.kreienkamp@la-z-boy.com> — 2026-06-22T13:42:21Z

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<font size="2"><div class="PlainText">&quot;normal backend cannot understand them.&quot;<br>
<br>
Thank you Hayato, that's what I was missing.&nbsp;&nbsp; I got it working now.<br>
<br>



<p style="FONT-SIZE: 10pt; FONT-FAMILY: ARIAL"><span style="FONT-FAMILY: Calibri"><font face="HelveticaNeueLT Std"><span style="FONT-FAMILY: Calibri"><strong><br></strong></span></font></span></p><p style="FONT-SIZE: 10pt; FONT-FAMILY: ARIAL"><span style="FONT-FAMILY: Calibri"><font face="HelveticaNeueLT Std"><span style="FONT-FAMILY: Calibri"><strong>Scot Kreienkamp&nbsp;| Applications Infrastructure Architect | La-Z-Boy Corporate</strong></span><br style="FONT-SIZE: 9pt"><span style="FONT-SIZE: 9pt"><span style="FONT-FAMILY: Calibri">One La-Z-Boy Drive | Monroe, Michigan 48162</span> 
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<p style="FONT-SIZE: 10pt; FONT-FAMILY: ARIAL"><font face="Arial"><span style="FONT-FAMILY: HelveticaNeueLT Std"><span style="FONT-SIZE: 9pt"><span style="FONT-FAMILY: Wingdings"><span style="FONT-FAMILY: HelveticaNeueLT Std"></span></span></span></span></font>&nbsp;</p>
<br>
-----Original Message-----<br>
From: Hayato Kuroda (Fujitsu) &lt;kuroda.hayato@fujitsu.com&gt; <br>
Sent: Monday, June 22, 2026 1:44 AM<br>
To: 'Matthew Tice' &lt;mjtice@gmail.com&gt;<br>
Cc: pgsql-general@lists.postgresql.org<br>
Subject: RE: set failover=true on existing logical replication slot PG18<br>
<br>
Dear Matthew, Scot,<br>
<br>
There are no ways to control default value of failover. Regarding the way for<br>
changing the value, yes, ALTER_REPLICATION_SLOT replication command is an only<br>
way to do that. Note that it's acceptable only when the backend is in the<br>
replication mode - normal backend cannot understand them.<br>
<br>
Best regards,<br>
Hayato Kuroda<br>
FUJITSU LIMITED<br>
<br>
</div></font>

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