Обсуждение: Typo in perform.sgml?
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
On Sat, Dec 7, 2019 at 12:05 PM Tatsuo Ishii <ishii@sraoss.co.jp> 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.
Julien Rouhaud <rjuju123@gmail.com> writes:
> On Sat, Dec 7, 2019 at 12:05 PM Tatsuo Ishii <ishii@sraoss.co.jp> 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
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
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>
> 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
On Sun, Dec 8, 2019 at 3:51 AM Tatsuo Ishii <ishii@sraoss.co.jp> 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!
Julien Rouhaud <rjuju123@gmail.com> writes:
> On Sun, Dec 8, 2019 at 3:51 AM Tatsuo Ishii <ishii@sraoss.co.jp> 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