Re: BUG #13994: Documentation of pg_notify is incorrect.

On Sun, 28 Feb 2016 23:20:40 +0000
junkmesend@gmail.com wrote:

> The following bug has been logged on the website:
>
> Bug reference:      13994
> Logged by:          Peter McGeeney
> Email address:      junkmesend@gmail.com
> PostgreSQL version: 9.5.1
> Operating system:   Windows 8.1
> Description:
>
> The documentation at
>
> http://www.postgresql.org/docs/9.5/static/sql-notify.html
>
> Recommends the command...
>
> SELECT pg_notify('fo' || 'o', 'pay' || 'load');
>
> which doesn't work but
>
> PERFORM pg_notify('fo' || 'o', 'pay' || 'load');
>
> does work, as explained here.
>
> http://stackoverflow.com/questions/5412474/using-pg-notify-in-postgresql-trigger-function?lq=1

This is working as documented. The trigger function is using language
plpgsql, but the psql session is sql. SELECT works differently in plpgsql
than in sql. Specifically it requires a destination for the result.
Otherwise use PERFORM.

See the fine manual:

http://www.postgresql.org/docs/9.5/static/plpgsql-statements.html#PLPGSQL-STATEMENTS-SQL-NORESULT

-dg

--
David Gould              510 282 0869         daveg@sonic.net
If simplicity worked, the world would be overrun with insects.