GUC context information in the document.

Hello, I had a question that whether a change of some GUC
parameter needs restart or not and similar questions come every
now and then.

As shown below, descriptions about GUC context is surely put
there but I believe the average reader of the document doesn't
recognize that clearly while looking into an item without
comparing it with several other itmes that he/she knows how
behave.

Addition to that, the description for PGC_POSTMASTER doesn't say
that it also can be set on command line, and description for
PGC_SIGHUP doesn't state clearly that realoading makes it
effective, and PGC_USERSET has even no description.

If I'm not missing anyting, putting stereotyped information about
GUC contexts like following would be usable.

> share_buffers (integer), (effective after server restart)

> log_destination (string), (effetive after config reload)

> log_min_duration_statement (integer), (effective in-session, superuser only)

> DateStyle (string), (effective in-session)

What do you think about this?

regards,

=====
The typical descriptions are listed below.

A. PGC_POSTMASTER

http://www.postgresql.org/docs/devel/static/runtime-config-resource.html#RUNTIME-CONFIG-RESOURCE-MEMORY

> shared_buffers (integer)
> ... This parameter can only be set at server start.

B. PGC_SIGHUP

http://www.postgresql.org/docs/devel/static/runtime-config-logging.html#GUC-LOG-DESTINATION

> log_destination (string)
> ... This parameter can only be set in the postgresql.conf
> file or on the server command line.

C. PGC_SUSET

http://www.postgresql.org/docs/devel/static/runtime-config-logging.html#GUC-LOG-MIN-DURATION-STATEMENT

> log_min_duration_statement (integer)
> ... Only superusers can change this setting.

D. PGC_USERSET

http://www.postgresql.org/docs/devel/static/runtime-config-client.html#GUC-DATESTYLE

> DateStyle (string)
... nothing about GUC context is written ...

--
Kyotaro Horiguchi
NTT Open Source Software Center