> From: Andreas Joseph Krogh <andr...@visena.com>
>To: pgsql-hackers@postgresql.org 
>Sent: Wednesday, 27 May 2015, 13:55
>Subject: Re: [HACKERS] Triggers on transaction?
> 
>
>På onsdag 27. mai 2015 kl. 12:42:29, skrev Marko Tiikkaja <ma...@joh.to>:
>On 5/27/15 12:39 PM, Jordan Gigov wrote:
>>> I found myself in need of triggers that are run only once per transaction,
>>> rather than per row or statement within the transaction. Meaning it will
>>> always be deferred and never called twice for the same transaction.
>>
>>What's the use case?
> 
> 
>I've often needed this for stuff like:
> 
>UPDATE some_table SET col = 'foo' where id = 1;
>UPDATE some_table SET col = 'bar' where id = 1;
> 
>I want the "on-tx"-trigger to only run once, and on the last update of "col" 
>so that it sees 'bar'.
> 



I often have similar requirements, and usually end up having to track what's 
already been updated with a trigger or similar then finally do the work in a 
deferred trigger.  I'd have thought something more like FOR EACH { ROW | 
STATEMENT } PER TRANSACTION would be more fitting.


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