From: Tom Lane <tgl@sss.pgh.pa.us>
To: Robert Haas <robertmhaas@gmail.com>
cc: Peter Eisentraut <peter.eisentraut@2ndquadrant.com>,
        Alvaro Herrera <alvherre@2ndquadrant.com>,
        Josh berkus <josh@agliodbs.com>, Peter Geoghegan <pg@heroku.com>,
        Noah Misch <noah@leadboat.com>,
        David Rowley <david.rowley@2ndquadrant.com>,
        Amit Kapila <amit.kapila16@gmail.com>,
        Magnus Hagander <magnus@hagander.net>,
        Bruce Momjian <bruce@momjian.us>,
        PostgreSQL-development <pgsql-hackers@postgresql.org>
Subject: Re: Rename max_parallel_degree?
In-reply-to: 
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References: <20160531195553.GA895326@alvherre.pgsql>
 <31423.1464725081@sss.pgh.pa.us>
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Comments: In-reply-to Robert Haas <robertmhaas@gmail.com>
	message dated "Tue, 31 May 2016 21:57:44 -0400"
Date: Tue, 31 May 2016 22:02:51 -0400
Message-ID: <13950.1464746571@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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