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From: Bruce Momjian <bruce@momjian.us>
To: petermpallesen@gmail.com
To: pgsql-docs@lists.postgresql.org
Subject: Re: Not using suppress_redundant_updates_trigger in sql-createtrigger.html#examples
Date: Tue, 16 Jun 2020 06:36:44 -0400
Message-ID: <20200616103644.GE31175@momjian.us> (raw)
In-Reply-To: <159195294959.673.5752624528747900508@wrigleys.postgresql.org>
References: <159195294959.673.5752624528747900508@wrigleys.postgresql.org>

On Fri, Jun 12, 2020 at 09:09:09AM +0000, PG Doc comments form wrote:
> The following documentation comment has been logged on the website:
> 
> Page: https://www.postgresql.org/docs/12/bug-reporting.html
> Description:
> 
> Hi 
> I was stumbling across the trigger function
> ‘suppress_redundant_updates_trigger’ in
> https://www.postgresql.org/docs/devel/functions-trigger.html and I would
> just ask if there is any reason of this not being int the documentation in 
> https://www.postgresql.org/docs/13/sql-createtrigger.html. 
> So after
> 
> Call a function to log updates of accounts, but only if something changed:
> 
> CREATE TRIGGER log_update
>     AFTER UPDATE ON accounts
>     FOR EACH ROW
>     WHEN (OLD.* IS DISTINCT FROM NEW.*)
>     EXECUTE FUNCTION log_account_update();
> 
> There could be an alternative implementation as well
> 
> CREATE TRIGGER log_update
>     AFTER UPDATE ON accounts
>     FOR EACH ROW
>     EXECUTE FUNCTION log_account_update();
> 
> CREATE TRIGGER suppress_redundant_account_after_updates
> AFTER UPDATE ON accounts
> FOR EACH ROW EXECUTE FUNCTION suppress_redundant_updates_trigger();
> 
> 
> Just to introduce and like the feature.
> 
> Thank you for your great work best regards

I have created the attached patch to mention
suppress_redundant_updates_trigger() in this case.  I don't think having
an actual example is warranted.

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

  The usefulness of a cup is in its emptiness, Bruce Lee

Attachments:

trigger.diff (text/x-diff, 544B) download
diff --git a/doc/src/sgml/ref/create_trigger.sgml b/doc/src/sgml/ref/create_trigger.sgml
index 303881fcfb..8cfac0fbc6 100644
--- a/doc/src/sgml/ref/create_trigger.sgml
+++ b/doc/src/sgml/ref/create_trigger.sgml
@@ -582,7 +582,9 @@ CREATE TRIGGER check_update
 </programlisting>
 
    Call a function to log updates of <literal>accounts</literal>, but only if
-   something changed:
+   something changed
+   (<function>suppress_redundant_updates_trigger()</function> can also be
+   helpful here):
 
 <programlisting>
 CREATE TRIGGER log_update

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  To: pgsql-docs@postgresql.org
  Cc: bruce@momjian.us, petermpallesen@gmail.com, pgsql-docs@lists.postgresql.org
  Subject: Re: Not using suppress_redundant_updates_trigger in sql-createtrigger.html#examples
  In-Reply-To: <20200616103644.GE31175@momjian.us>

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