Re: Rename max_parallel_degree?

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Robert Haas <robertmhaas(at)gmail(dot)com>
Cc: Peter Eisentraut <peter(dot)eisentraut(at)2ndquadrant(dot)com>, Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>, Josh berkus <josh(at)agliodbs(dot)com>, Peter Geoghegan <pg(at)heroku(dot)com>, Noah Misch <noah(at)leadboat(dot)com>, David Rowley <david(dot)rowley(at)2ndquadrant(dot)com>, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>, Magnus Hagander <magnus(at)hagander(dot)net>, Bruce Momjian <bruce(at)momjian(dot)us>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Rename max_parallel_degree?
Date: 2016-06-01 02:02:51
Message-ID: 13950.1464746571@sss.pgh.pa.us
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Robert Haas <robertmhaas(at)gmail(dot)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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