Thread: view rules

Hi everybody,
I am trying to create an update rule for a view. It's created fine, and
I can find it in pg_rules, but when I try to update the view, I get the
usual error:
ERROR: Cannot update a view without an appropriate rule.

My rule definitions is as follows:
CREATE RULE update_priority AS ON UPDATE TO progress_report
WHERE NEW.priority != OLD.priority
DO INSTEAD UPDATE activity SET priority=NEW.priority
WHERE activity.productcode = OLD.product_code
AND activity.actname=OLD.component;

I am trying to update the view as follows:
update progress_report set priority=2 where product_code='m3' and
component='act';

activity is a table. I can't figure out what's wrong. Please help.
thanks,

Oleg

On Thu, Dec 06, 2001 at 01:17:44PM -0700, Oleg Lebedev wrote:
> Hi everybody,
> I am trying to create an update rule for a view. It's created fine, and
> I can find it in pg_rules, but when I try to update the view, I get the
> usual error:
> ERROR: Cannot update a view without an appropriate rule.
> 
> My rule definitions is as follows:
> CREATE RULE update_priority AS ON UPDATE TO progress_report
> WHERE NEW.priority != OLD.priority
> DO INSTEAD UPDATE activity SET priority=NEW.priority
> WHERE activity.productcode = OLD.product_code
> AND activity.actname=OLD.component;
> 
> I am trying to update the view as follows:
> update progress_report set priority=2 where product_code='m3' and
> component='act';
> 

The View/Rule system is very picky: you have to have rules to cover
_every_ possible update case before it'll allow any to go through.
The usual way aroun this is to create a 'do nothing' rule with no WHERE
clause:

ifs_test=# create rule update_any as ON UPDATE TO progress_report DO INSTEAD NOTHING;

ifs_test=# select * from progress_report;priority | product_code | component 
----------+--------------+-----------       1 |            3 | act
(1 row)

ifs_test=# update progress_report set priority=2 where product_code='3' and component='act';
UPDATE 1
ifs_test=# select * from progress_report;priority | product_code | component 
----------+--------------+-----------       2 |            3 | act
(1 row)

(I fudged your product code, since I'd created an int in my test case: if
you'd sent along schema for the table, my test would have gone _much_ faster)

Ross
-- 
Ross Reedstrom, Ph.D.                                 reedstrm@rice.edu
Executive Director                                  phone: 713-348-6166
Gulf Coast Consortium for Bioinformatics              fax: 713-348-6182
Rice University MS-39
Houston, TX 77005

Thanks a lot Ross,
that fixed my problem. I think it should be mentioned in PostgreSQL tutorial (in Al Bundy's
example).
thanks again,

Oleg

"Ross J. Reedstrom" wrote:

> On Thu, Dec 06, 2001 at 01:17:44PM -0700, Oleg Lebedev wrote:
> > Hi everybody,
> > I am trying to create an update rule for a view. It's created fine, and
> > I can find it in pg_rules, but when I try to update the view, I get the
> > usual error:
> > ERROR: Cannot update a view without an appropriate rule.
> >
> > My rule definitions is as follows:
> > CREATE RULE update_priority AS ON UPDATE TO progress_report
> > WHERE NEW.priority != OLD.priority
> > DO INSTEAD UPDATE activity SET priority=NEW.priority
> > WHERE activity.productcode = OLD.product_code
> > AND activity.actname=OLD.component;
> >
> > I am trying to update the view as follows:
> > update progress_report set priority=2 where product_code='m3' and
> > component='act';
> >
>
> The View/Rule system is very picky: you have to have rules to cover
> _every_ possible update case before it'll allow any to go through.
> The usual way aroun this is to create a 'do nothing' rule with no WHERE
> clause:
>
> ifs_test=# create rule update_any as ON UPDATE TO progress_report DO INSTEAD NOTHING;
>
> ifs_test=# select * from progress_report;
>  priority | product_code | component
> ----------+--------------+-----------
>         1 |            3 | act
> (1 row)
>
> ifs_test=# update progress_report set priority=2 where product_code='3' and component='act';
> UPDATE 1
> ifs_test=# select * from progress_report;
>  priority | product_code | component
> ----------+--------------+-----------
>         2 |            3 | act
> (1 row)
>
> (I fudged your product code, since I'd created an int in my test case: if
> you'd sent along schema for the table, my test would have gone _much_ faster)
>
> Ross
> --
> Ross Reedstrom, Ph.D.                                 reedstrm@rice.edu
> Executive Director                                  phone: 713-348-6166
> Gulf Coast Consortium for Bioinformatics              fax: 713-348-6182
> Rice University MS-39
> Houston, TX 77005