Re: doc: Improve description of io_combine_limit and io_max_combine_limit GUCs

I wrote:
>
> On Thu, Oct 30, 2025 at 4:31 PM Fujii Masao <masao.fujii@gmail.com> wrote:
> >
> > I also noticed another issue in the io_max_combine_limit docs.
> > Since its context is PGC_POSTMASTER, shouldn't the following
> > description be updated to say "This parameter can only be set at server start"?
> >
> >          This parameter can only be set in
> >          the <filename>postgresql.conf</filename> file or on the server
> >          command line.
> >
>
> Nice catch! I am going to check if there are other GUCs with
> PGC_POSTMASTER and wrong documentation. I'll come back with an
> updated version of the patch.
>

I looked through all parameters in guc_parameters.dat that have
PGC_POSTMASTER context. I lack the patience to go through all the GUCs,
so I only checked those with PGC_POSTMASTER context for now.

Here is the list of the parameters whose descriptions don't say
"This parameter can only be set at server start."
1. Parameters with "This parameter can only be set in
   <filename>postgresql.conf</filename> file or on the server command
   line" instead of "This parameter can only be set at server start".
   I fixed these.
 * track_commit_timestamp
 * io_max_combine_limit
 * event_source
2. Parameters that have no description in the docs specifying when they
   could be set. I added "This parameter can only be set at server
   start" to their description.
 * wal_decode_buffer_size
 * max_notify_queue_pages
 * shared_memory_type
 * dynamic_shared_memory_type
 * debug_io_direct
3. The following parameters have one phrase "These parameters can only
   be set at server start" for the whole group before their
   descriptions. So they are okay.
 * recovery_target
 * recovery_target_name
 * recovery_target_time
 * recovery_target_xid
 * recovery_target_lsn
 * recovery_target_inclusive
 * recovery_target_timeline
 * recovery_target_action
4. Other
 * config_file
   It has GUC_DISALLOW_IN_FILE flag, so its doc looks ok to me: "This
   parameter can only be set on the <command>postgres</command> command
   line."
 * trace_connection_negotiation
   It is not documented at all. Should it be fixed?
 * huge_pages
   It has a phrase "With on, failure to request huge pages will prevent
   the server from starting up." from which it could be concluded that
   this parameter must be set at server start, but I added this
   explicitly anyway.

I'm attaching these changes as a separate patch just in case. You can
squash them if you like. Not sure what to do with the commitfest entry.
Should I change it back to Needs review?

Best regards,
Karina Litskevich
Postgres Professional: http://postgrespro.com/