From: | Boszormenyi Zoltan <zb(at)cybertec(dot)at> |
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To: | Noah Misch <noah(at)leadboat(dot)com>, Michael Meskes <meskes(at)postgresql(dot)org>, Robert Haas <robertmhaas(at)gmail(dot)com>, PG Hackers <pgsql-hackers(at)postgresql(dot)org>, Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>, Bruce Momjian <bruce(at)momjian(dot)us> |
Subject: | Re: ECPG FETCH readahead |
Date: | 2012-04-10 07:35:21 |
Message-ID: | 4F83E2B9.3030302@cybertec.at |
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Lists: | pgsql-hackers |
2012-04-08 19:38 keltezéssel, Michael Meskes írta:
> 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 fetch 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,
Zoltán Böszörményi
--
----------------------------------
Zoltán Böszörményi
Cybertec Schönig& Schönig GmbH
Gröhrmühlgasse 26
A-2700 Wiener Neustadt, Austria
Web: http://www.postgresql-support.de
http://www.postgresql.at/
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