From: Tom Lane <tgl@sss.pgh.pa.us>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Peter Eisentraut <peter.eisentraut@2ndquadrant.com>
Cc: Alvaro Herrera <alvherre@2ndquadrant.com>
Cc: Josh berkus <josh@agliodbs.com>
Cc: Peter Geoghegan <pg@heroku.com>
Cc: Noah Misch <noah@leadboat.com>
Cc: David Rowley <david.rowley@2ndquadrant.com>
Cc: Amit Kapila <amit.kapila16@gmail.com>
Cc: Magnus Hagander <magnus@hagander.net>
Cc: Bruce Momjian <bruce@momjian.us>
Cc: PostgreSQL-development <pgsql-hackers@postgresql.org>
Subject: Re: Rename max_parallel_degree?
Date: Tue, 31 May 2016 22:02:51 -0400
Message-ID: <13950.1464746571@sss.pgh.pa.us> (raw)
In-Reply-To: <CA+Tgmob-FSzqXkN7isOP16z+ABdvnQc5KYBqZmH1M0=WBuM80w@mail.gmail.com>
References: <20160531195553.GA895326@alvherre.pgsql>
<31423.1464725081@sss.pgh.pa.us>
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Robert Haas <robertmhaas@gmail.com> writes:
> Now, this case is a little trickier. If we called it simply
> parallel_degree rather than max_parallel_degree, then it would have
> the same name as the reloption. But the reloption sets an exact
> value, and the GUC sets a cap, which is a significant difference.
The reloption does not set an exact value, according to the code:
/*
* Use the table parallel_degree, but don't go further than
* max_parallel_degree.
*/
parallel_degree = Min(rel->rel_parallel_degree, max_parallel_degree);
although the existing documentation for it is so vague that you
couldn't tell from that.
regards, tom lane
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Cc: tgl@sss.pgh.pa.us, robertmhaas@gmail.com, peter.eisentraut@2ndquadrant.com, alvherre@2ndquadrant.com, josh@agliodbs.com, pg@heroku.com, noah@leadboat.com, david.rowley@2ndquadrant.com, amit.kapila16@gmail.com, magnus@hagander.net, bruce@momjian.us
Subject: Re: Rename max_parallel_degree?
In-Reply-To: <13950.1464746571@sss.pgh.pa.us>
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