Re: [PATCH 4/4] Add tests to dblink covering use of COPY TO FUNCTION

From: Jeff Davis <pgsql(at)j-davis(dot)com>
To: Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>
Cc: Daniel Farina <drfarina(at)gmail(dot)com>, Hannu Krosing <hannu(at)krosing(dot)net>, Greg Smith <greg(at)2ndquadrant(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com>, Daniel Farina <dfarina(at)truviso(dot)com>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: [PATCH 4/4] Add tests to dblink covering use of COPY TO FUNCTION
Date: 2009-11-25 08:37:10
Message-ID: 1259138230.19289.253.camel@jdavis
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On Wed, 2009-11-25 at 09:23 +0100, Pavel Stehule wrote:
> > If SRFs use a tuplestore in that situation, it sounds like that should
> > be fixed. Why do we need to provide alternate syntax involving COPY?
>
> It isn't problem of SRF function design. It allow both mode - row and
> tuplestor.

select * from generate_series(1,1000000000) limit 1;

That statement takes a long time, which indicates to me that it's
materializing the result of the SRF. And there's no insert there.

> This is problem of INSERT statement, resp. INSERT INTO
> SELECT implementation.

If "tmp" is a new table, and "zero" is a table with a million zeros in
it, then:
insert into tmp select 1/i from zero;
fails instantly. That tells me that it's not materializing the result of
the select; rather, it's feeding the rows in one at a time.

Can show me in more detail what you mean? I'm having difficulty
understanding your short replies.

Regards,
Jeff Davis

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