From: | Amit Langote <Langote_Amit_f8(at)lab(dot)ntt(dot)co(dot)jp> |
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To: | Amit Langote <amitlangote09(at)gmail(dot)com>, David Rowley <david(dot)rowley(at)2ndquadrant(dot)com> |
Cc: | PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: slight tweaks to documentation about runtime pruning |
Date: | 2018-12-14 02:52:03 |
Message-ID: | 304131bd-e1a5-8cb1-25b6-5b567463fde2@lab.ntt.co.jp |
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Lists: | pgsql-hackers |
On 2018/12/10 0:57, Amit Langote wrote:
> On Sun, Dec 9, 2018 at 8:13 PM David Rowley
> <david(dot)rowley(at)2ndquadrant(dot)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.
I updated the patch. Regarding whether we should mention "(never
executed)", it wouldn't hurt to mention it imho, exactly because it's
shown in the place of showing loops=0. How about the attached?
Thanks,
Amit
Attachment | Content-Type | Size |
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runtime-pruning-doc-tweak-v2.patch | text/plain | 1.0 KB |
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