On 10/12/2012 08:48 PM, Greg Stark wrote:
On Fri, Oct 12, 2012 at 7:55 AM, Simon Riggs <si...@2ndquadrant.com> wrote:
AFAICS all RULEs can be re-expressed as Triggers or Views.
This is a bizarre discussion. Firstly this isn't even close to true.
The whole source of people's discontentment is that triggers are *not*
equivalent to rules. If they were then they wouldn't be so upset.
Secondly the only reason views work is because they're implemented
using rules.
Nobody is discussing deprecating VIEWs.
And SELECT rules that are the basis of VIEWs are deprecated
from being an independent user-visible feature for quite some
time already
If you want to do anything similar but different from
views you would need to use rules as well. I'm still waiting on
updateable views for example.
You CAN do these using triggers, that is the main reason we
have INSTEAD triggers.
It sounds like what people are really looking for is to move the
section of the manual describing rules to an "internals" section of
the manual and add a note saying "do not try to use rules to implement
triggers. they are not triggers" that explains how they're different
and what they're useful for.
Moving them to internals _and_ adding a note to not use them
directly for any user code seems like a good plan.
And replacing the original RULES page with suggestion to look
under internals.
In general user manuals, especially ones written like Unix man pages,
tend to describe what things do without explaining why that might be
useful. That's leaves users faced with a decision between trying
similar-sounding features like rules and triggers and they might pick
the wrong one. The Postgres manual is better than most in this respect
but this is one area where it might pay to be extra clear.
-------------------
Hannu Krosing
--
Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-hackers
