Horton

Re: On disable_cost

Richard Guo <guofenglinux@gmail.com>

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From: Richard Guo <guofenglinux@gmail.com>
To: Alexander Lakhin <exclusion@gmail.com>
Cc: Robert Haas <robertmhaas@gmail.com>, Tom Lane <tgl@sss.pgh.pa.us>, David Rowley <dgrowleyml@gmail.com>, Heikki Linnakangas <hlinnaka@iki.fi>, Peter Geoghegan <pg@bowt.ie>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2024-09-06T09:51:05Z
Lists: pgsql-hackers 
On Fri, Sep 6, 2024 at 5:27 PM Richard Guo <guofenglinux@gmail.com> wrote:
> On Fri, Sep 6, 2024 at 5:00 PM Alexander Lakhin <exclusion@gmail.com> wrote:
> > static void
> > label_sort_with_costsize(PlannerInfo *root, Sort *plan, double limit_tuples)

> (I'm a little surprised that this does not cause any plan diffs in the
> regression tests.)

Ah I see.  label_sort_with_costsize is only used to label the Sort
node nicely for EXPLAIN, and usually we do not display the cost
numbers in regression tests.

Thanks
Richard

Commits

  1. Doc: add detail about EXPLAIN's "Disabled" property

  2. Adjust EXPLAIN's output for disabled nodes

  3. Fix order of parameters in a cost_sort call

  4. Show number of disabled nodes in EXPLAIN ANALYZE output.

  5. Treat number of disabled nodes in a path as a separate cost metric.

  6. Remove grotty use of disable_cost for TID scan plans.