+
+ <para>
+ The fourth form changes the default tablespace of the database.
+ Only the database owner or a superuser can do this; you must also have
+ create privilege for the new tablespace.
+ This command physically moves any tables or indexes in the database's old
+ default tablespace to the new tablespace. Note that tables and indexes
+ in non-default tablespaces are not affected.
+ </para>
+
+ <para>
+ The remaining forms change the session default for a run-time
+ configuration variable for a <productname>PostgreSQL</productname>
+ database. Whenever a new session is subsequently started in that
+ database, the specified value becomes the session default value.
+ The database-specific default overrides whatever setting is present
+ in <filename>postgresql.conf</> or has been received from the
+ <command>postgres</command> command line. Only the database
+ owner or a superuser can change the session defaults for a
+ database. Certain variables cannot be set this way, or can only be
+ set by a superuser.
+ </para>