PGC_POSTMASTER implies that it's an instance-wide setting. Is is intentional? I can understand that it's more secure for this not to be changeable in an existing session, but it's also much less usable if you can't set it per-database and per-user. Maybe it should be PGC_SUSET ?
It’s my misunderstanding I thought PGC_POSTMASTER set only by
superuser and changed with a hard restart
I attach a patch that incorporate the comments and uses similar routines
with the rest of the file rather than using command tag
