Re: slight tweaks to documentation about runtime pruning

Amit Langote <amitlangote09@gmail.com>

From: Amit Langote <amitlangote09@gmail.com>
To: David Rowley <david.rowley@2ndquadrant.com>
Cc: Amit Langote <Langote_Amit_f8@lab.ntt.co.jp>, PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2018-12-09T15:57:39Z
Lists: pgsql-hackers
On Sun, Dec 9, 2018 at 8:13 PM David Rowley
<david.rowley@2ndquadrant.com> wrote:
> listp1 was scanned twice (loops=2), listp2 was scanned just once.
>
> Now it is true that if the subplan was executed 0 times that it will
> appear as "(never executed)", but do we really need to explain in this
> area that "(never executed)" means loops=0?

Ah, I see what you mean.  So, "(never executed)" is not the only sign
of of run-time pruning occurring.  The value of loops can be different
for different subplans / partitions, and it being lower for a given
subplan means that the subplan has been pruned more number of times.

Thanks,
Amit


Commits

  1. Clarify runtime pruning in EXPLAIN