[Seino Yuki <seinoyu@oss.nttdata.com>]

Hello,

Add a reference method for shared_memory_size_in_huge_pages
with the "SHOW" command.

The current documentation explains the use of the postgres -C command,
but this method may be limited in DBaaS or managed service environments.
In particular, CloudNativePG does not allow the server to be stopped,
making the execution of $ postgres -C impossible.

Alternatively, the "SHOW" command can be used, though the documentation 
states,
"Note that the server must be shut down to view this runtime-computed 
parameter.[1]"
This wording could be misunderstood to imply that the parameter cannot 
be accessed
while the server is running.

[1] - 
https://www.postgresql.org/docs/devel/kernel-resources.html#LINUX-HUGE-PAGES

Regards,
--
Yuki Seino
NTT DATA CORPORATION

Attachments:

v1-0001-shared_memory_size_in_huge_pages_using_show.patch (text/x-diff, 809B) download
diff --git a/doc/src/sgml/runtime.sgml b/doc/src/sgml/runtime.sgml
index 2c4d5ef640..aaac025c90 100644
--- a/doc/src/sgml/runtime.sgml
+++ b/doc/src/sgml/runtime.sgml
@@ -1441,6 +1441,17 @@ $ <userinput>grep ^Hugepagesize /proc/meminfo</userinput>
 Hugepagesize:       2048 kB
 $ <userinput>ls /sys/kernel/mm/hugepages</userinput>
 hugepages-1048576kB  hugepages-2048kB
+</programlisting>
+
+     If the server is running, this parameter can be viewed using the 
+     <command>SHOW</command> command.
+     This might look like:
+<programlisting>
+postgres=# <userinput>SHOW shared_memory_size_in_huge_pages;</userinput>
+ shared_memory_size_in_huge_pages 
+----------------------------------
+ 3170
+(1 row)
 </programlisting>
 
      In this example the default is 2MB, but you can also explicitly request