Re: Smaller data types use same disk space

On Wed, Jul 25, 2012 at 1:35 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> "McGehee, Robert" <Robert(dot)McGehee(at)geodecapital(dot)com> writes:
>> One might even imagine a future version of PostgreSQL using an
>> efficient disk layout that may not match the table layout in order to
>> avoid wasted space from padding.
>
> Yeah, this has been discussed multiple times. The sticking point is
> the extra infrastructure needed to have a physical column numbering
> different from the user-visible numbering, and the 100% certainty of
> introducing a lot of bugs due to bits of code using one type of column
> number where they should have used the other. We'll probably get it
> done someday, but don't hold your breath ...

Has there been any discussion of providing the ability to re-order
table columns through an ALTER TABLE command? I would love to see
this; when I add in a new column, I often want to put it next to
something just to be more visually appealing when I'm running ad-hoc
queries. It could potentially address this problem as well.

Mike