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Re: [HACKERS] Performance testing of COPY (SELECT) TO

From: Zoltan Boszormenyi <zboszor(at)dunaweb(dot)hu>
To: Andrew Dunstan <andrew(at)dunslane(dot)net>
Cc: Bruce Momjian <bruce(at)momjian(dot)us>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>,pgsql-patches(at)postgresql(dot)org
Subject: Re: [HACKERS] Performance testing of COPY (SELECT) TO
Date: 2006-08-28 15:33:23
Message-ID: 44F30CC3.2010002@dunaweb.hu (view raw or flat)
Thread:
Lists: pgsql-hackerspgsql-patches
Andrew Dunstan írta:
> Alvaro Herrera wrote:
>> Böszörményi Zoltán wrote:
>>  
>>> Hi,
>>>
>>> what's the problem with COPY view TO, other than you don't like it? :-)
>>>     
>>
>> The problem is that it required a ugly piece of code.  Not supporting it
>> means we can keep the code nice.  The previous discussion led to this
>> conclusion anyway so I don't know why we are debating it again.
>>
>>   
>
> What is so ugly about it? I haven't looked at the code, but I am 
> curious to know.
>
> I also don't recall the consensus being quite so clear cut. I guess 
> there is a case for saying that if it's not allowed then you know that 
> "COPY relname TO" is going to be fast. But, code aesthetics aside, the 
> reasons for disallowing it seem a bit thin, to me.
>
> cheers
>
> andrew
>

I would say the timing difference between
"COPY table TO" and "COPY (SELECT * FROM table) TO"
was  noise, so it's not even faster.

And an updatable VIEW *may* allow COPY view FROM...


Best regards,
Zoltán Böszörményi


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