Re: ALTER TABLE modifications

Rod Taylor writes:

> Yes, it is certainly fine to do so, but much faster to do the above.

Are table schema changes performance-sensitive operations, and are they
usually done in bulk? I doubt it.

> I've not found another database which allows this syntax. The suggestion
> of TRANSFORM was Toms and was a result of using an assignment cast by
> default. Do you have a better term I can use?

I'm not sure I buy this whole concept in the first place. If there is
no cast between type A and type B, then surely changing a table column
from A to B is nonsensical.

> -- or say Bytes to MBytes (original column is int8)
> ALTER TABLE tab ALTER col TYPE integer TRANSFORM col / (1024 * 1024);

You can do this using a plain column type change plus an UPDATE. I'd
prefer to keep these operations independent.

--
Peter Eisentraut peter_e(at)gmx(dot)net