Re: idea: storing view source in system catalogs - Mailing list pgsql-hackers

From Bruce Momjian
Subject Re: idea: storing view source in system catalogs
Date
Msg-id 200807142257.m6EMv9k19793@momjian.us
Whole thread Raw
In response to Re: idea: storing view source in system catalogs  ("Robert Haas" <robertmhaas@gmail.com>)
List pgsql-hackers
Added to TODO:
* Improve ability to modify views via ALTER TABLE  http://archives.postgresql.org/pgsql-hackers/2008-05/msg00691.php


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Robert Haas wrote:
> I think the real problem here is that PostgreSQL is very finicky about
> what operations you can perform on a view.  If I have a table foo and
> I define a view bar that uses foo and a view baz that uses bar, I can
> add a column to foo without a problem, and, similarly, I can also drop
> or alter a column in foo that is not used by bar.  But the same is not
> true of bar.  I can't make any changes at all to bar without dropping
> and recreating it, and that means I have to drop and recreate baz as
> well.  If there are only two views involved, this is not so bad, but
> frequently there are a whole slough of views baz1, baz2, ..., bazn
> that all depend on bar, and I have to drop and recreate every single
> one of them.
> 
> I could understand the need to do this if I were (for example)
> changing the type of some column that was used by all of these views,
> but that's usually not the case.  Normally I'm just adding new columns
> to foo and bar, and none of the other views are changing... but they
> have to be recreated anyway.
> 
> As a side note, handling this problem gracefully would go a long way
> to solving the original poster's concern about *-expansion. If
> updating to the latest version of "*" just required re-executing
> CREATE OR REPLACE VIEW ..., it would be relatively simple.  As things
> stand now, it requires DROP VIEW ... CASCADE; CREATE OR REPLACE VIEW
> ...; followed by recreating all of the dependent objects.
> 
> ...Robert
> 
> -- 
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--  Bruce Momjian  <bruce@momjian.us>        http://momjian.us EnterpriseDB
http://enterprisedb.com
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