Postgres Pro
Downloads
Home   >   mailing lists

Re: Multiple NOTIFY is ignored - Mailing list pgsql-general

From Igor Neyman
Subject Re: Multiple NOTIFY is ignored
Date
Msg-id MWHPR07MB2877DCFF6374EF9E1507EE5CDA000@MWHPR07MB2877.namprd07.prod.outlook.com
Whole thread Raw
In response to Re: Multiple NOTIFY is ignored  ("David G. Johnston" <david.g.johnston@gmail.com>)
List pgsql-general
Tree view

 

From: pgsql-general-owner@postgresql.org [mailto:pgsql-general-owner@postgresql.org] On Behalf Of David G. Johnston
Sent: Thursday, July 28, 2016 11:05 AM
To: Markus Kolb <markus.kolb+postgres@tower-net.de>
Cc: pgsql-general@postgresql.org
Subject: Re: [GENERAL] Multiple NOTIFY is ignored

 

On Thu, Jul 28, 2016 at 10:29 AM, Markus Kolb <markus.kolb+postgres@tower-net.de> wrote:

If I only do one
SELECT dblink_connect('{0}', '{1}'); SELECT dblink('{2}', '{3}'); SELECT dblink_disconnect('{4}');
where {3} is
NOTIFY upd_pgm, '0|UPDATE|A|'; NOTIFY upd_pgm, '0|DELETE|A|'

only the notify with UPDATE is recognized.

 

​"​

dblink executes a query (usually a SELECT, but it can be any SQL statement that returns rows) in a remote database.

​"​

 

 

​As defined in the dblink docs your query isn't supported - its doesn't return rows.  I don't know the interaction that makes the separate executions succeed by I'd advise simply bypassing the issue and doing:

 

WHERE {3} is

SELECT pg_notify('{2}','{UPDATE NOTIFY}), pg_notify('{3}','{DELETE NOTIFY}');

 

Not tested and I've never used NOTIFY but the select makes it return rows.

 

I'm not positive how execution order plays out here, you may want to try "VALUES()" instead of multiple columns.

 

David J.

 

 

Well,

 

“dblink_exec executes a command (that is, any SQL statement that doesn't return rows) in a remote database.”

 

Regards,

Igor

pgsql-general by date:

Previous
From: Igor Neyman
Date:
Subject: Re: Uber migrated from Postgres to MySQL
Next
From: Alex Ignatov
Date:
Subject: Re: Uber migrated from Postgres to MySQL