[pg@h1 ~]$ vacuumdb --freeze template0
vacuumdb: could not connect to database template0: FATAL:  database "template0" is not currently accepting connections
[pg@h1 ~]$ psql template0
psql: FATAL:  database "template0" is not currently accepting connections
[pg@h1 ~]$ PGOPTIONS='-c gp_session_role=utility' psql template1
psql (8.2.15)
Type "help" for help.
 
template1=# set allow_system_table_mods='DML';
SET
template1=# update pg_database set datallowconn='t' where datname='template0';
UPDATE 1
template1=# \c template0
You are now connected to database "template0" as user "pg".
template0=# vacuum freeze ;
VACUUM
template0=# \q
[pg@h1 ~]$ PGOPTIONS='-c gp_session_role=utility' psql template1
psql (8.2.15)
Type "help" for help.
 
template1=# set allow_system_table_mods='DML';
SET
template1=# update pg_database set datallowconn='f' where datname='template0';
UPDATE 1

How vacuum template0