Re: Wrong insert before trigger examples

[Bruce Momjian]

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  <br...@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">