Re: [HACKERS] Logical replication in the same cluster - Mailing list pgsql-hackers

From Bruce Momjian
Subject Re: [HACKERS] Logical replication in the same cluster
Date
Msg-id 20170426215617.GA6147@momjian.us
Whole thread Raw
In response to Re: [HACKERS] Logical replication in the same cluster  (Petr Jelinek <petr.jelinek@2ndquadrant.com>)
List pgsql-hackers
On Wed, Apr 26, 2017 at 11:41:51PM +0200, Petr Jelinek wrote:
> On 26/04/17 18:59, Bruce Momjian wrote:
> > I tried setting up logical replication on the same server between two
> > different databases, and got, from database test:
> > 
> >     test=> CREATE TABLE test (x INT PRIMARY KEY);
> >     CREATE TABLE
> >     test=>
> >     test=> INSERT INTO test VALUES (1);
> >     INSERT 0 1
> >     test=> CREATE PUBLICATION mypub FOR TABLE test;
> >     CREATE PUBLICATION
> > 
> > then from database test2:
> > 
> >     test2=> CREATE TABLE test (x INT PRIMARY KEY);
> >     CREATE TABLE
> >     test2=> CREATE SUBSCRIPTION mysub CONNECTION 'dbname=test port=5432'
> >     PUBLICATION mypub;
> >     NOTICE:  synchronized table states
> > 
> > and it just hangs.  My server logs say:
> > 
> >     2017-04-26 12:50:53.694 EDT [29363] LOG:  logical decoding found initial
> >     starting point at 0/15FF3E0
> >     2017-04-26 12:50:53.694 EDT [29363] DETAIL:  1 transaction needs to
> >     finish.
> > 
> > Is this expected?  I can get it working from two different clusters.
> > 
> 
> Yes that's result of how logical replication slots work, the transaction
> that needs to finish is your transaction. It can be worked around by
> creating the slot manually via the SQL interface for example and create
> the subscription using WITH (NOCREATE SLOT, SLOT NAME = 'your slot') .

Oh, OK.  Is there a way we can give users a hint do that if they try
what I did?

--  Bruce Momjian  <bruce@momjian.us>        http://momjian.us EnterpriseDB
http://enterprisedb.com

+ As you are, so once was I.  As I am, so you will be. +
+                      Ancient Roman grave inscription +



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