Explicitely mention that some GUC variables cannot be changed at

runtime.

diff --git a/doc/src/sgml/runtime.sgml b/doc/src/sgml/runtime.sgml
index f64719bd78c5c7df48c38dbcf0e632a5fa7651d8..5c67f70863e40942f519793a70a7822593ab6c6d 100644 (file)
--- a/doc/src/sgml/runtime.sgml
+++ b/doc/src/sgml/runtime.sgml
@@ -1,5 +1,5 @@
 
 
 
@@ -541,8 +541,11 @@ env PGOPTIONS='-c geqo=off' psql
 SET ENABLE_SEQSCAN TO OFF;
 
     If SET is allowed, it overrides all other sources of
-    values for the parameter.  Superusers are allowed to SET
-    more values than ordinary users.
+    values for the parameter.  Superusers are allowed to
+    SET more values than ordinary users.  Some parameters
+    cannot be SET even by superusers: for example,
+    if they control behavior that cannot reasonably be changed without
+    restarting PostgreSQL.