On Mon, 6 May 2002 08:44:27 +0900 "Hiroshi Inoue" <[EMAIL PROTECTED]> wrote: > > -----Original Message----- > > From: Manfred Koizar > > > > If there is interest in reducing on-disk tuple header size and I have > > not missed any strong arguments against dropping t_natts, I'll > > investigate further. Comments? > > If a dbms is proper, it prepares a mechanism from the first > to handle ADD COLUMN without touching the tuples. If the > machanism is lost(I believe so) by removing t_natts, I would > say good bye to PostgreSQL.
IMHO, the current ADD COLUMN mechanism is a hack. Besides requiring redundant on-disk data (t_natts), it isn't SQL compliant (because default values or NOT NULL can't be specified), and depends on a low-level kludge (that the storage system will return NULL for any attnums > the # of the attributes stored in the tuple). While instantaneous ADD COLUMN is nice, I think it's counter- productive to not take advantage of a storage space optimization just to preserve a feature that is already semi-broken. Cheers, Neil -- Neil Conway <[EMAIL PROTECTED]> PGP Key ID: DB3C29FC ---------------------------(end of broadcast)--------------------------- TIP 1: subscribe and unsubscribe commands go to [EMAIL PROTECTED]
