Message-ID: <4F83E2B9.3030302@cybertec.at>
Date: Tue, 10 Apr 2012 09:35:21 +0200
From: Boszormenyi Zoltan <zb@cybertec.at>
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To: Noah Misch <noah@leadboat.com>, Michael Meskes <meskes@postgresql.org>,
	Robert Haas <robertmhaas@gmail.com>,
	PG Hackers <pgsql-hackers@postgresql.org>,
	Heikki Linnakangas <heikki.linnakangas@enterprisedb.com>,
	Bruce Momjian <bruce@momjian.us>
Subject: Re: ECPG FETCH readahead
References: 
 <CA+TgmoaBGLpW5V3nFES-McLbZyY_9nUvpnFLjT7zAYuVPu809A@mail.gmail.com>
	<4F6D9893.3030300@cybertec.at>
	<20120329004323.GA17329@tornado.leadboat.com>
	<4F74409C.3050904@cybertec.at>
	<20120329170341.GA4142@tornado.leadboat.com>
	<4F74E6A7.8040204@cybertec.at>
	<20120407112008.GA2286@feivel.credativ.lan>
	<20120407155042.GB11987@tornado.leadboat.com>
	<20120408142501.GA21513@feivel.credativ.lan>
	<4F81BE55.1010904@cybertec.at>
	<20120408173859.GA4915@feivel.credativ.lan>
In-Reply-To: <20120408173859.GA4915@feivel.credativ.lan>
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2012-04-08 19:38 keltez=C3=A9ssel, Michael Meskes =C3=ADrta:
> On Sun, Apr 08, 2012 at 06:35:33PM +0200, Boszormenyi Zoltan wrote:
>> Do you want me to change this or will you do it? I am on holiday
>> and will be back to work on wednesday.
> I don't think waiting till later this week is a real problem.

OK.

>
>> The possibility to test different readahead window sizes
>> without modifying the source and recompiling was useful.
> Sure, but you can still do that when not defining a fixed number in the
> statement.

OK.

>
>> The -R option simply provides a default without ornamenting
>> the DECLARE statement.
> Could you please incorporate these changes, too, when you're back from =
vacation?

Sure.

So, it's established that a specified READAHEAD N should not
be overridden. Even an explicit READAHEAD 1.

Only a non-decorated cursor can be overridden, even if
a different default readahead window size is specified with
e.g. "ecpg -R 8". If ECPGFETCHSZ is not present, 8 will be used,
if ECPGFETCHSZ is present, its value will be used. ECPGopen()
will need an extra bool argument to distinguish this.

Is this acceptable? Noah, Michael?

>
>>> I cannot find a test that tests the environment variable giving the f=
etch size.
>>> Could you please point me to that?
>> I didn't write such a test. The reason is that while variables are
>> exported by make from the Makefile to the binaries run by make
>> e.g.  CFLAGS et.al. for $(CC), "make check" simply runs pg_regress
>> once which uses its own configuration file that doesn't have a
>> way to set or unset an environment variable. This could be a useful
>> extension to pg_regress though.
> How about calling setenv() from the test program itself?

Sure, I didn't think about it. It should be done before the
first EXEC SQL OPEN cursor.

Best regards,
Zolt=C3=A1n B=C3=B6sz=C3=B6rm=C3=A9nyi

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