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From: Gavin Flower <GavinFlower@archidevsys.co.nz>
To: Andrew Dunstan <andrew@dunslane.net>
Cc: Heikki Linnakangas <hlinnakangas@vmware.com>
Cc: Andres Freund <andres@anarazel.de>
Cc: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Craig Ringer <craig@2ndQuadrant.com>
Cc: Claudio Freire <klaussfreire@gmail.com>
Cc: Merlin Moncure <mmoncure@gmail.com>
Cc: David Greco <David_Greco@harte-hanks.com>
Cc: pgsql-performance@postgresql.org <pgsql-performance@postgresql.org>
Subject: Re: Poor performance using CTE
Date: Thu, 22 Nov 2012 10:24:55 +1300
Message-ID: <50AD46A7.103@archidevsys.co.nz> (raw)
In-Reply-To: <50AD2E88.4000902@dunslane.net>
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	<50AD2E88.4000902@dunslane.net>

On 22/11/12 08:42, Andrew Dunstan wrote:
>
> On 11/21/2012 02:30 PM, Gavin Flower wrote:
>> WITH FENCE foo AS (SELECT ...)
>> default?
>>
>>
>> WITHOUT FENCE foo AS (SELECT ...)     :-)
>> Nah!
>> I prefer this, but it is too specific to 'WITH',
>> and very unSQL standardish!
>>
>> Alternatively one of the following
>>
>>  1. WITH UNFENCED foo AS (SELECT ...)
>>  2. WITH NO FENCE foo AS (SELECT ...)
>>  3. WITH NOT FENCE foo AS (SELECT ...)
>>
>> I loke the firsat variant, but the 3rd is
>> most SQL standardish!
>>
>
> As Tom (I think) pointed out, we should not have a syntax tied to CTEs.
>
> cheers
>
> andrew
>
If other SQL constructs have a optimisation fence, then the FENCE & NOT 
FENCE syntax can be used theire as well.

So what am I missing? (obviously WITHOUT FENCE would not make sense 
elsewhere, but I wasn't really being serious when I suggested it!)





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  Cc: GavinFlower@archidevsys.co.nz, andrew@dunslane.net, hlinnakangas@vmware.com, andres@anarazel.de, tgl@sss.pgh.pa.us, craig@2ndQuadrant.com, klaussfreire@gmail.com, mmoncure@gmail.com, David_Greco@harte-hanks.com
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