Added to TODO: > o Allow column display reordering by recording a display, > storage, and permanent id for every column? > > http://archives.postgresql.org/pgsql-hackers/2006-12/msg00782.php >
--------------------------------------------------------------------------- Jim C. Nasby wrote: > On Thu, Dec 21, 2006 at 11:43:27AM -0500, Tom Lane wrote: > > Andrew Dunstan <[EMAIL PROTECTED]> writes: > > > Tom Lane wrote: > > >> You could make a case that we need *three* numbers: a permanent column > > >> ID, a display position, and a storage position. > > > > > Could this not be handled by some catalog fixup after an add/drop? If we > > > get the having 3 numbers you will almost have me convinced that this > > > might be too complicated after all. > > > > Actually, the more I think about it the more I think that 3 numbers > > might be the answer. 99% of the code would use only the permanent ID. > > Display position would be used in *exactly* one place, namely while > > expanding "SELECT foo.*" --- I can't think of any other part of the > > backend that would care about it. (Obviously, client-side code such > > as psql's \d would use it too.) Use of storage position could be > > localized into a few low-level tuple access functions, probably. > > > > The problems we've been having with the concept stem precisely from > > trying to misuse either display or storage position as a permanent ID. > > That's fine as long as it actually is permanent, but as soon as you > > want to change it then you have problems. We should all understand > > this perfectly well from a database theory standpoint: pg_attribute > > has to have a persistent primary key. (attrelid, attnum) is that key, > > and we can't go around altering a column's attnum without creating > > problems for ourselves. > > Is there enough consensus on this to add it to the TODO? > -- > Jim Nasby [EMAIL PROTECTED] > EnterpriseDB http://enterprisedb.com 512.569.9461 (cell) > > ---------------------------(end of broadcast)--------------------------- > TIP 3: Have you checked our extensive FAQ? > > http://www.postgresql.org/docs/faq -- Bruce Momjian [EMAIL PROTECTED] EnterpriseDB http://www.enterprisedb.com + If your life is a hard drive, Christ can be your backup. + ---------------------------(end of broadcast)--------------------------- TIP 7: You can help support the PostgreSQL project by donating at http://www.postgresql.org/about/donate