[lug] Postgres Alter table

[rm at mamma.varadinet.de]

On Thu, Jul 12, 2001 at 09:51:43PM -0600, Ryan Kirkpatrick wrote:
> 	This would be even easier if you could drop a column. Instead of
> selecting out the entire table, select out just the column you want to
> convert. Then alter the table to drop the column and then recreate. After
> that load the data back in. One would have to be careful about order,
> maybe pull out a key field along with it.
> 	Though PGSQL does not yet support dropping a column from a table,
> but if I remember correctly, it is on the TODO list.

Hmm, as far as i understand the storage manager of postgresql this doesn't
seem trivial. Taken the fact that altering the data type of a column hope-
fully happens rather seldom i can easily live without it. 

> 	This is not that much of a worry. Indices will be automatically
> dropped along with the table when it is dropped. So you only need to
> recreate them (probably from the original scheme you used to build the
> table in the first place). Same story for constraints. Views probably will
> not be dropped with the table and will have to be reconstructed. Only
> other worries is if you have sequences assocaited with the table (in which
> case handle them like views, though remember to restore their 'next'
> value), and foriegn key relationships.

You're right, indices and constraints will be dropped (but not recreated).
What about triggers and rules? (i never checked this).

 Ralf