As it mentions in the PostgreSQL manual
Currently, views are read only: the system will not allow an insert,
update, or delete on a view. You can get the effect of an updatable
view by creating rules that rewrite inserts, etc. on the view into
appropriate actions on other tables.
What are the benefits to creating an updatable view using rules vs a straight insert/update operation? Are there any hidden “gotchas” that I would need to be aware of?
–Update–
It seems that 9.3 will include updatable views:
http://www.depesz.com/2012/12/11/waiting-for-9-3-support-automatically-updatable-views/
The next release of PostgreSQL is planned to be the 9.3 release. A tentative schedule for this version has a release in the third quarter of 2013.
This is still a ways away but it looks like this may make life a touch easier for any who need it.
You can have a stable interface to a client and still change the structure of underlying tables as long as you edit the rules on the view accordingly. I happened to use this in the past, when I had to remove a table and didn’t want to wake a difficult client, so I provided a view as drop in and the client never noticed the change.
In a multi-user environment you can manage privileges on one view more easily than privileges on multiple tables.
Another benefit is in the last word of your quote: tables – plural. This way, a client can send one query and you can change multiple underlying tables. You can achieve this with triggers, too, mostly.
Other than that, it’s regularly simpler to operate with triggers.