Re: logical column ordering

OK, so let me summarize here (the other posts in this subthread are
discussing the user interface, not the use cases, so I'll respond here).

There are two main use cases:

1) change the order of columns in "SELECT *"

- display columns so that related ones grouped together
(irrespectedly whether they were added later, etc.)

- keep columns synced with COPY

- requires user interface (ALTER TABLE _ ALTER COLUMN _ SET ORDER _)

2) optimization of physical order (efficient storage / tuple deforming)

- more efficient order for storage (deforming)

- may be done manually by reordering columns in CREATE TABLE

- should be done automatically (no user interface required)

- seems useful both for on-disk physical tuples, and virtual tuples

Anything else?

--
Tomas Vondra http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services