Implicit rule created for materialized views

Hi

In playing with materialized views, I noticed that they still seem to
have an _RETURN rule implicitly created like a regular view. This
doesn't seem right to me - is there a reason?

viper:~ dpage$ /usr/local/pgsql-9.3/bin/psql -p 5433 -U postgres
psql (9.3beta1)
Type "help" for help.

postgres=# CREATE MATERIALIZED VIEW ruletest AS SELECT * FROM pg_class;
SELECT 298
postgres=# SELECT pg_get_ruledef(oid) FROM pg_rewrite WHERE ev_class =
'ruletest'::regclass;
pg_get_ruledef
-----------------------------------------------------------------
CREATE RULE "_RETURN" AS +
ON SELECT TO ruletest DO INSTEAD SELECT pg_class.relname, +
pg_class.relnamespace, +
pg_class.reltype, +
pg_class.reloftype, +
pg_class.relowner, +
pg_class.relam, +
pg_class.relfilenode, +
pg_class.reltablespace, +
pg_class.relpages, +
pg_class.reltuples, +
pg_class.relallvisible, +
pg_class.reltoastrelid, +
pg_class.reltoastidxid, +
pg_class.relhasindex, +
pg_class.relisshared, +
pg_class.relpersistence, +
pg_class.relkind, +
pg_class.relnatts, +
pg_class.relchecks, +
pg_class.relhasoids, +
pg_class.relhaspkey, +
pg_class.relhasrules, +
pg_class.relhastriggers, +
pg_class.relhassubclass, +
pg_class.relispopulated, +
pg_class.relfrozenxid, +
pg_class.relminmxid, +
pg_class.relacl, +
pg_class.reloptions +
FROM pg_class;
(1 row)

--
Dave Page
Blog: http://pgsnake.blogspot.com
Twitter: @pgsnake

EnterpriseDB UK: http://www.enterprisedb.com
The Enterprise PostgreSQL Company