Re: Smaller data types use same disk space

On Wed, Jul 25, 2012 at 5:20 PM, Mike Christensen <mike@kitchenpc.com> wrote:
> On Wed, Jul 25, 2012 at 1:35 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> "McGehee, Robert" <Robert.McGehee@geodecapital.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.

see: http://wiki.postgresql.org/wiki/Alter_column_position
as well as extensive discussion in the archives.

merlin