| From: | Gavin Flower <GavinFlower(at)archidevsys(dot)co(dot)nz> |
|---|---|
| To: | Andrew Dunstan <andrew(at)dunslane(dot)net> |
| Cc: | Heikki Linnakangas <hlinnakangas(at)vmware(dot)com>, Andres Freund <andres(at)anarazel(dot)de>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Craig Ringer <craig(at)2ndQuadrant(dot)com>, Claudio Freire <klaussfreire(at)gmail(dot)com>, Merlin Moncure <mmoncure(at)gmail(dot)com>, David Greco <David_Greco(at)harte-hanks(dot)com>, "pgsql-performance(at)postgresql(dot)org" <pgsql-performance(at)postgresql(dot)org> |
| Subject: | Re: Poor performance using CTE |
| Date: | 2012-11-21 21:24:55 |
| Message-ID: | 50AD46A7.103@archidevsys.co.nz |
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| Thread: | |
| Lists: | pgsql-performance |
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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