Date: Tue, 31 Mar 2020 17:08:02 -0400
From: Bruce Momjian <bruce@momjian.us>
To: mib@nic.at, pgsql-docs@lists.postgresql.org
Subject: Re: Wrong insert before trigger examples
Message-ID: <20200331210802.GC17676@momjian.us>
References: <158089540905.1098.15071165437284409576@wrigleys.postgresql.org>
 <20200313225637.GB10187@momjian.us>
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Patch applied back through PG 10.

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On Fri, Mar 13, 2020 at 06:56:37PM -0400, Bruce Momjian wrote:
> On Wed, Feb  5, 2020 at 09:36:49AM +0000, PG Doc comments form wrote:
> > The following documentation comment has been logged on the website:
> > 
> > Page: https://www.postgresql.org/docs/12/ddl-partitioning.html
> > Description:
> > 
> > Hi,
> > 
> > I just noticed that the example in 5.11.3.1. Point 5 contains an "before
> > insert trigger" which will not work anymore (I think since Postgres 12).
> > This trigger is not needed anymore and causes an error message.
> 
> Sorry for the delay in replying.  I was able to successfully create the
> trigger:
> 
> 	CREATE TABLE measurement (
> 	    city_id         int not null,
> 	    logdate         date not null,
> 	    peaktemp        int,
> 	    unitsales       int
> 	);
> 
> 	CREATE TABLE measurement_y2006m02 (
> 	    CHECK ( logdate >= DATE '2006-02-01' AND logdate < DATE '2006-03-01' )
> 	) INHERITS (measurement);
> 
> 	CREATE INDEX measurement_y2006m02_logdate ON measurement_y2006m02 (logdate);
> 
> 	CREATE OR REPLACE FUNCTION measurement_insert_trigger()
> 	RETURNS TRIGGER AS $$
> 	BEGIN
> 	    INSERT INTO measurement_y2008m01 VALUES (NEW.*);
> 	    RETURN NULL;
> 	END;
> 	$$
> 	LANGUAGE plpgsql;
> 
> 	CREATE TRIGGER insert_measurement_trigger
> 	    BEFORE INSERT ON measurement
> 	    FOR EACH ROW EXECUTE FUNCTION measurement_insert_trigger();
> 
> There are actually two definitions of 'measurement' in the docs above,
> and you might have used the partitioned one:
> 
> 	CREATE TABLE measurement (
> 	    city_id         int not null,
> 	    logdate         date not null,
> 	    peaktemp        int,
> 	    unitsales       int
> 	) PARTITION BY RANGE (logdate);
> 
> I have developed the attached patch to clarify which definition to use. 
> I am not sure if more extensive changes are needed.
> 
> -- 
>   Bruce Momjian  <bruce@momjian.us>        https://momjian.us
>   EnterpriseDB                             https://enterprisedb.com
> 
> + As you are, so once was I.  As I am, so you will be. +
> +                      Ancient Roman grave inscription +

> diff --git a/doc/src/sgml/ddl.sgml b/doc/src/sgml/ddl.sgml
> index 8d3a0d1c22..d2588876c0 100644
> --- a/doc/src/sgml/ddl.sgml
> +++ b/doc/src/sgml/ddl.sgml
> @@ -4103,8 +4103,8 @@ ALTER INDEX measurement_city_id_logdate_key
>       <title>Example</title>
>  
>       <para>
> -      We use the same <structname>measurement</structname> table we used
> -      above.  To implement partitioning using inheritance, use
> +      We use the non-partitioned <structname>measurement</structname>
> +      table above.  To implement partitioning using inheritance, use
>        the following steps:
>  
>        <orderedlist spacing="compact">


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

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