Message-ID: <448463DC.8030306@dunslane.net>
Date: Mon, 05 Jun 2006 13:03:24 -0400
From: Andrew Dunstan <andrew@dunslane.net>
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To: Mark Woodward <pgsql@mohawksoft.com>
CC: Tom Lane <tgl@sss.pgh.pa.us>, "Jim C. Nasby" <jnasby@pervasive.com>,
	Zoltan Boszormenyi <zboszor@dunaweb.hu>, pgsql-hackers@postgresql.org
Subject: Re: [PERFORM] psql -A (unaligned format) eats too much
References: <44835834.2020309@dunaweb.hu> <44835F86.5040008@dunaweb.hu>
	<20060605152258.GT53487@pervasive.com>
	<20512.1149521250@sss.pgh.pa.us>
	<20060605155349.GU53487@pervasive.com>
	<20813.1149523235@sss.pgh.pa.us>
	<18006.24.91.171.78.1149526092.squirrel@mail.mohawksoft.com>
	<44845E86.3080001@dunslane.net>
	<18067.24.91.171.78.1149526905.squirrel@mail.mohawksoft.com>
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Mark Woodward wrote:
>>>>
>>>>
>>>>         
>>> Wouldn't the "COPY (select ...) TO STDOUT" format being discussed solve
>>> this for free?
>>>
>>>
>>>
>>>       
>> It won't solve it in the general case for clients that expect a result
>> set. ISTM that "use a cursor" is a perfectly reasonable answer, though.
>>     
>
> I'm not sure I agree -- surprise!
>
> psql is often used as a command line tool and using a cursor is not
> acceptable.
>
> Granted, with an unaligned output, perhaps psql should not buffer the
> WHOLE result at once, but without rewriting that behavior, a COPY from
> query may be close enough.
>
>   

You have missed my point. Surprise!

I didn't say it wasn't OK in the psql case, I said it wasn't helpful in 
the case of *other* libpq clients.

Expecting clients generally to split and interpret COPY output is not 
reasonable, but if they want large result sets they should use a cursor.

cheers

andrew