Обсуждение: [GENERAL] How to add columns to view with dependencies

On Sun, Apr 16, 2017 at 08:02:54PM -0700, Guyren Howe wrote:
> Seems like a simple question, but I’ve never found a good answer to this and similar issues.
>
> I would think it was safe to let me add columns to a view on which other views depend, but Postgres won’t let me.
>
> I can imagine ways of sort-of dealing with this. I might maintain a SQL file with views to create in a suitable
order,Then I could drop all views, edit the definition of one, then run the file, but this is awfully tedious. 
>
> What is best practice in this situation?

If you're not re-ordering existing columns, you can use CREATE OR REPLACE VIEW

Justin

Guyren Howe <guyren@gmail.com> writes:
> Seems like a simple question, but I’ve never found a good answer to this and similar issues.
> I would think it was safe to let me add columns to a view on which other views depend, but Postgres won’t let me.

> I can imagine ways of sort-of dealing with this. I might maintain a SQL file with views to create in a suitable
order,Then I could drop all views, edit the definition of one, then run the file, but this is awfully tedious. 

> What is best practice in this situation?

Hm ... all currently-supported versions of Postgres will allow, eg,

regression=# create table t1 (f1 int, f2 int, f3 int);
CREATE TABLE
regression=# create view v1 as select f1 from t1;
CREATE VIEW
regression=# create or replace view v1 as select f1, f2 from t1;
CREATE VIEW
regression=# create view v2 as select * from v1;
CREATE VIEW
regression=# create or replace view v1 as select f1, f2, f3 from t1;
CREATE VIEW

So I think your options are (1) explain what you're really doing,
or (2) update.

            regards, tom lane

On Sun, Apr 16, 2017 at 08:02:54PM -0700, Guyren Howe wrote:

> I can imagine ways of sort-of dealing with this. I might
> maintain a SQL file with views to create in a suitable order,
> Then I could drop all views, edit the definition of one, then
> run the file, but this is awfully tedious.

This, kept under version control, seems best practice,
regardless of what PG supports making the above easier.

Karsten
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