Re: logical column ordering

On Feb 27, 2015 5:02 PM, "Alvaro Herrera" <alvherre(at)2ndquadrant(dot)com> wrote:
>
> Arthur Silva wrote:
>
> > Sorry to intrude, I've been following this post and I was wondering if
it
> > would allow (in the currently planed form or in the future) a wider set
of
> > non-rewriting DDLs to Postgres. For example, drop a column without
> > rewriting the table.
>
> Perhaps. But dropping a column already does not rewrite the table, only
> marks the column as dropped in system catalogs, so do you have a better
> example.
>
> One obvious example is that you have
>
> CREATE TABLE t (
> t1 int,
> t3 int
> );
>
> and later want to add t2 in the middle, the only way currently is to
> drop the table and start again (re-creating all dependant views, FKs,
> etc). With the patch you will be able to add the column at the right
> place. If no default value is supplied for the new column, no table
> rewrite is necessary at all.
>
> --
> Álvaro Herrera http://www.2ndQuadrant.com/
> PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

Cool! I didn't know I could drop stuff without rewriting.

Ya, that's another example, people do these from GUI tools. That's a nice
side effect. Cool (again)!