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List:       postgresql-general
Subject:    Re: [HACKERS] foreign key locks
From:       Noah Misch <noah () leadboat ! com>
Date:       2012-10-31 21:01:29
Message-ID: 20121031210129.GD29247 () tornado ! leadboat ! com
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On Wed, Oct 31, 2012 at 05:22:10PM -0300, Alvaro Herrera wrote:
> Simon Riggs wrote:
> > On 31 October 2012 19:35, Noah Misch <noah@leadboat.com> wrote:
> > > +1.  I had not considered this angle during previous reviews, but I agree with
> > > Andres's position.  Since this patch does not strengthen the strongest tuple
> > > lock relative to its PostgreSQL 9.2 counterpart, that lock type should
> > > continue to use the syntax "FOR UPDATE".  It will come to mean "the lock type
> > > sufficient for all possible UPDATEs of the row".
> 
> Yeah, I agree with this too.
> 
> > So we have syntax
> > 
> > FOR NON KEY UPDATE
> > FOR KEY UPDATE
> > 
> > KEY is the default, so FOR UPDATE is a synonym of FOR KEY UPDATE
> 
> Not really sure about the proposed syntax, but yes clearly we need some
> other syntax to mean "FOR NON KEY UPDATE".  I would rather keep FOR
> UPDATE to mean what I currently call FOR KEY UPDATE.  More proposals for
> the other (weaker) lock level welcome (but if you love FOR NON KEY
> UPDATE, please chime in too)

Agree on having "FOR UPDATE" without any "FOR KEY UPDATE" synonym.  For the
weaker lock, I mildly preferred the proposal of "FOR NO KEY UPDATE".  NON KEY
captures the idea better in English, but NO is close enough and already part
of the SQL lexicon.


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