Horton

Re: why not parallel seq scan for slow functions

Simon Riggs <simon@2ndquadrant.com>

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From: Simon Riggs <simon@2ndquadrant.com>
To: Amit Kapila <amit.kapila16@gmail.com>
Cc: Robert Haas <robertmhaas@gmail.com>, Jeff Janes <jeff.janes@gmail.com>, Dilip Kumar <dilipbalaut@gmail.com>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2017-08-22T07:31:25Z
Lists: pgsql-hackers 
On 21 August 2017 at 11:42, Amit Kapila <amit.kapila16@gmail.com> wrote:

>> or of 2)
>> treating cost = speed, so we actually reduce the cost of a parallel
>> plan rather than increasing it so it is more likely to be picked.
>>
>
> Yeah, this is what is being currently followed for costing of parallel
> plans and this patch also tries to follow the same.

OK, I understand this better now, thanks.

-- 
Simon Riggs                http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

Commits

  1. Rewrite the code that applies scan/join targets to paths.

  2. Teach create_projection_plan to omit projection where possible.

  3. Make the upper part of the planner work by generating and comparing Paths.