From: Bruce Momjian <pgman@candle.pha.pa.us>
Message-Id: <200405100358.i4A3wCp02854@candle.pha.pa.us>
Subject: Re: Adding MERGE to the TODO list (resend with subject)
In-Reply-To: <409DC28A.7010509@familyhealth.com.au>
To: Christopher Kings-Lynne <chriskl@familyhealth.com.au>
Date: Sun, 9 May 2004 23:58:12 -0400 (EDT)
Cc: Alvaro Herrera <alvherre@dcc.uchile.cl>, elein <elein@varlena.com>,
	PostgreSQL-development <pgsql-hackers@postgresql.org>
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Added to TODO:

	* Add MERGE command that does UPDATE, or on failure, INSERT


---------------------------------------------------------------------------

Christopher Kings-Lynne wrote:
> >>Except you can keep trying and trying without the outermost transaction 
> >>failing.
> > 
> > But that won't provide the necessary next key locking you mentioned in
> > your first email, will it?
> 
> No, but since I can loop an infinite number of times until either the 
> update or insert works, I don't need next key locking.
> 
> BTW, the reference in MySQL:
> 
> http://dev.mysql.com/doc/mysql/en/REPLACE.html
> 
> Hmm...no refernce to next key locking. Maybe that's an Innodb thing...
> 
> Anyway, you can see how they've implemented their algorithm.
> 
> Here is docs on the DB2 merge command from which the standard was derived:
> 
> http://databasejournal.com/features/db2/article.php/10896_3322041_2
> 
> Chris
> 
> ---------------------------(end of broadcast)---------------------------
> TIP 9: the planner will ignore your desire to choose an index scan if your
>       joining column's datatypes do not match
> 

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