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* Typo in perform.sgml?
@ 2019-12-07 11:05 Tatsuo Ishii <[email protected]>
2019-12-07 13:01 ` Re: Typo in perform.sgml? Julien Rouhaud <[email protected]>
0 siblings, 1 reply; 7+ messages in thread
From: Tatsuo Ishii @ 2019-12-07 11:05 UTC (permalink / raw)
To: [email protected]
Around line 904 of perform.sgml
"These node types have the ability to discard subnodes which they are
able to determine won't contain any records required by the query."
I was not able to parse this. Maybe "that they " is needed after
"determine"?
Best regards,
--
Tatsuo Ishii
SRA OSS, Inc. Japan
English: http://www.sraoss.co.jp/index_en.php
Japanese:http://www.sraoss.co.jp
^ permalink raw reply [nested|flat] 7+ messages in thread
* Re: Typo in perform.sgml?
2019-12-07 11:05 Typo in perform.sgml? Tatsuo Ishii <[email protected]>
@ 2019-12-07 13:01 ` Julien Rouhaud <[email protected]>
2019-12-07 16:46 ` Re: Typo in perform.sgml? Tom Lane <[email protected]>
0 siblings, 1 reply; 7+ messages in thread
From: Julien Rouhaud @ 2019-12-07 13:01 UTC (permalink / raw)
To: Tatsuo Ishii <[email protected]>; +Cc: [email protected]
On Sat, Dec 7, 2019 at 12:05 PM Tatsuo Ishii <[email protected]> wrote:
>
> Around line 904 of perform.sgml
>
> "These node types have the ability to discard subnodes which they are
> able to determine won't contain any records required by the query."
>
> I was not able to parse this. Maybe "that they " is needed after
> "determine"?
Agreed. Also, I'm not a native english speaker either, but the
"which" sounds weird too. How about:
These node types have the ability to discard subnodes for which they
are able to determine that won't contain any records required by the
query.
^ permalink raw reply [nested|flat] 7+ messages in thread
* Re: Typo in perform.sgml?
2019-12-07 11:05 Typo in perform.sgml? Tatsuo Ishii <[email protected]>
2019-12-07 13:01 ` Re: Typo in perform.sgml? Julien Rouhaud <[email protected]>
@ 2019-12-07 16:46 ` Tom Lane <[email protected]>
2019-12-07 20:56 ` Re: Typo in perform.sgml? Tom Lane <[email protected]>
0 siblings, 1 reply; 7+ messages in thread
From: Tom Lane @ 2019-12-07 16:46 UTC (permalink / raw)
To: Julien Rouhaud <[email protected]>; +Cc: Tatsuo Ishii <[email protected]>; [email protected]
Julien Rouhaud <[email protected]> writes:
> On Sat, Dec 7, 2019 at 12:05 PM Tatsuo Ishii <[email protected]> wrote:
>> Around line 904 of perform.sgml
>> "These node types have the ability to discard subnodes which they are
>> able to determine won't contain any records required by the query."
>>
>> I was not able to parse this. Maybe "that they " is needed after
>> "determine"?
> Agreed. Also, I'm not a native english speaker either, but the
> "which" sounds weird too. How about:
> These node types have the ability to discard subnodes for which they
> are able to determine that won't contain any records required by the
> query.
Hm. A grammar purist would say that the "which" should be "that",
because it's introducing a restrictive clause. But I think the real
problem here is that "contain" is a crummy choice of verb: the notion
of a plan node "containing" records is what seems weird to me.
I think "produce" might work better. Also, there's a lot of unnecessary
words here; I think we should be trying to make the sentence shorter
not longer. How about something like
"These node types will discard subnodes when they detect that a
particular subnode won't produce any records required by the query."
Actually, that whole para could do with a rewrite; whoever wrote
it was obviously not familiar with Strunk & White's dictum
"Omit needless words".
regards, tom lane
^ permalink raw reply [nested|flat] 7+ messages in thread
* Re: Typo in perform.sgml?
2019-12-07 11:05 Typo in perform.sgml? Tatsuo Ishii <[email protected]>
2019-12-07 13:01 ` Re: Typo in perform.sgml? Julien Rouhaud <[email protected]>
2019-12-07 16:46 ` Re: Typo in perform.sgml? Tom Lane <[email protected]>
@ 2019-12-07 20:56 ` Tom Lane <[email protected]>
2019-12-08 02:51 ` Re: Typo in perform.sgml? Tatsuo Ishii <[email protected]>
0 siblings, 1 reply; 7+ messages in thread
From: Tom Lane @ 2019-12-07 20:56 UTC (permalink / raw)
To: Julien Rouhaud <[email protected]>; +Cc: Tatsuo Ishii <[email protected]>; [email protected]
I wrote:
> Actually, that whole para could do with a rewrite; whoever wrote
> it was obviously not familiar with Strunk & White's dictum
> "Omit needless words".
Looking closer, there were also some unnecessary inconsistencies with
the rest of the section, such as use of "records" rather than "rows",
and different markup choices. I propose the attached ... it's
actually a bit longer than the original, but that's because it
offers more details.
regards, tom lane
Attachments:
[text/x-diff] improve-subplan-pruning-docs.patch (1.6K, 2-improve-subplan-pruning-docs.patch)
download | inline diff:
diff --git a/doc/src/sgml/perform.sgml b/doc/src/sgml/perform.sgml
index 715aff6..0f61b09 100644
--- a/doc/src/sgml/perform.sgml
+++ b/doc/src/sgml/perform.sgml
@@ -896,15 +896,16 @@ EXPLAIN ANALYZE SELECT * FROM tenk1 WHERE unique1 < 100 AND unique2 > 9000
</para>
<para>
- Generally, the <command>EXPLAIN</command> output will display details for
- every plan node which was generated by the query planner. However, there
- are cases where the executor is able to determine that certain nodes are
- not required; currently, the only node types to support this are the
- <literal>Append</literal> and <literal>MergeAppend</literal> nodes. These
- node types have the ability to discard subnodes which they are able to
- determine won't contain any records required by the query. It is possible
- to determine that nodes have been removed in this way by the presence of a
- "Subplans Removed" property in the <command>EXPLAIN</command> output.
+ Normally, <command>EXPLAIN</command> will display every plan node
+ created by the planner. However, there are cases where the executor
+ can determine that certain nodes need not be executed because they
+ cannot produce any rows, based on parameter values that were not
+ available at planning time. (Currently this can only happen for child
+ nodes of an Append or MergeAppend node that is scanning a partitioned
+ table.) When this happens, those plan nodes are omitted from
+ the <command>EXPLAIN</command> output and a <literal>Subplans
+ Removed: <replaceable>N</replaceable></literal> annotation appears
+ instead.
</para>
</sect2>
^ permalink raw reply [nested|flat] 7+ messages in thread
* Re: Typo in perform.sgml?
2019-12-07 11:05 Typo in perform.sgml? Tatsuo Ishii <[email protected]>
2019-12-07 13:01 ` Re: Typo in perform.sgml? Julien Rouhaud <[email protected]>
2019-12-07 16:46 ` Re: Typo in perform.sgml? Tom Lane <[email protected]>
2019-12-07 20:56 ` Re: Typo in perform.sgml? Tom Lane <[email protected]>
@ 2019-12-08 02:51 ` Tatsuo Ishii <[email protected]>
2019-12-08 08:07 ` Re: Typo in perform.sgml? Julien Rouhaud <[email protected]>
0 siblings, 1 reply; 7+ messages in thread
From: Tatsuo Ishii @ 2019-12-08 02:51 UTC (permalink / raw)
To: [email protected]; +Cc: [email protected]; [email protected]
> I wrote:
>> Actually, that whole para could do with a rewrite; whoever wrote
>> it was obviously not familiar with Strunk & White's dictum
>> "Omit needless words".
>
> Looking closer, there were also some unnecessary inconsistencies with
> the rest of the section, such as use of "records" rather than "rows",
> and different markup choices. I propose the attached ... it's
> actually a bit longer than the original, but that's because it
> offers more details.
Thanks for looking into this. The patch looks much cleaner than
before.
Best regards,
--
Tatsuo Ishii
SRA OSS, Inc. Japan
English: http://www.sraoss.co.jp/index_en.php
Japanese:http://www.sraoss.co.jp
^ permalink raw reply [nested|flat] 7+ messages in thread
* Re: Typo in perform.sgml?
2019-12-07 11:05 Typo in perform.sgml? Tatsuo Ishii <[email protected]>
2019-12-07 13:01 ` Re: Typo in perform.sgml? Julien Rouhaud <[email protected]>
2019-12-07 16:46 ` Re: Typo in perform.sgml? Tom Lane <[email protected]>
2019-12-07 20:56 ` Re: Typo in perform.sgml? Tom Lane <[email protected]>
2019-12-08 02:51 ` Re: Typo in perform.sgml? Tatsuo Ishii <[email protected]>
@ 2019-12-08 08:07 ` Julien Rouhaud <[email protected]>
2019-12-08 15:37 ` Re: Typo in perform.sgml? Tom Lane <[email protected]>
0 siblings, 1 reply; 7+ messages in thread
From: Julien Rouhaud @ 2019-12-08 08:07 UTC (permalink / raw)
To: Tatsuo Ishii <[email protected]>; +Cc: Tom Lane <[email protected]>; [email protected]
On Sun, Dec 8, 2019 at 3:51 AM Tatsuo Ishii <[email protected]> wrote:
>
> > I wrote:
> >> Actually, that whole para could do with a rewrite; whoever wrote
> >> it was obviously not familiar with Strunk & White's dictum
> >> "Omit needless words".
> >
> > Looking closer, there were also some unnecessary inconsistencies with
> > the rest of the section, such as use of "records" rather than "rows",
> > and different markup choices. I propose the attached ... it's
> > actually a bit longer than the original, but that's because it
> > offers more details.
>
> Thanks for looking into this. The patch looks much cleaner than
> before.
I agree this is way better!
^ permalink raw reply [nested|flat] 7+ messages in thread
* Re: Typo in perform.sgml?
2019-12-07 11:05 Typo in perform.sgml? Tatsuo Ishii <[email protected]>
2019-12-07 13:01 ` Re: Typo in perform.sgml? Julien Rouhaud <[email protected]>
2019-12-07 16:46 ` Re: Typo in perform.sgml? Tom Lane <[email protected]>
2019-12-07 20:56 ` Re: Typo in perform.sgml? Tom Lane <[email protected]>
2019-12-08 02:51 ` Re: Typo in perform.sgml? Tatsuo Ishii <[email protected]>
2019-12-08 08:07 ` Re: Typo in perform.sgml? Julien Rouhaud <[email protected]>
@ 2019-12-08 15:37 ` Tom Lane <[email protected]>
0 siblings, 0 replies; 7+ messages in thread
From: Tom Lane @ 2019-12-08 15:37 UTC (permalink / raw)
To: Julien Rouhaud <[email protected]>; +Cc: Tatsuo Ishii <[email protected]>; [email protected]
Julien Rouhaud <[email protected]> writes:
> On Sun, Dec 8, 2019 at 3:51 AM Tatsuo Ishii <[email protected]> wrote:
>> Thanks for looking into this. The patch looks much cleaner than
>> before.
> I agree this is way better!
Pushed like that, then.
regards, tom lane
^ permalink raw reply [nested|flat] 7+ messages in thread
end of thread, other threads:[~2019-12-08 15:37 UTC | newest]
Thread overview: 7+ messages (download: mbox mbox.gz follow: Atom feed)
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2019-12-07 11:05 Typo in perform.sgml? Tatsuo Ishii <[email protected]>
2019-12-07 13:01 ` Julien Rouhaud <[email protected]>
2019-12-07 16:46 ` Tom Lane <[email protected]>
2019-12-07 20:56 ` Tom Lane <[email protected]>
2019-12-08 02:51 ` Tatsuo Ishii <[email protected]>
2019-12-08 08:07 ` Julien Rouhaud <[email protected]>
2019-12-08 15:37 ` Tom Lane <[email protected]>
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