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Re: Rename max_parallel_degree?

Tom Lane <tgl@sss.pgh.pa.us>

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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>
Date: 2016-06-01T02:02:51Z
Lists: pgsql-hackers 
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