On Wednesday 22 March 2006 12:58, Kevin Grittner wrote: > On this page: > > http://www.postgresql.org/docs/8.1/interactive/sql-altertable.html > > there is this user comment: > > -------------------- > > To change the data type of a column, do this: > > BEGIN; > ALTER TABLE tab ADD COLUMN new_col new_data_type; > UPDATE tab SET new_col = CAST(old_col AS new_data_type); > ALTER TABLE tab RENAME old_col TO temp_name; > ALTER TABLE tab RENAME new_col TO old_col; > ALTER TABLE tab DROP COLUMN temp_name; > COMMIT; > > You might then want to do VACUUM FULL tab to reclaim the disk space > used by the expired rows. > > -------------------- > > The 8.1 release (and the 8.0 release) support the same functionality > with a single line: > > ALTER TABLE tab ALTER COLUMN old_col TYPE new_data_type; > > I think the user comment should be removed, unless there is some > benefit to using the multi-step process. If there is some benefit, I > think it should be described, so that users know when to use it instead > of the simpler technique. >
I believe Tom's comments in this email apply similarly here. http://archives.postgresql.org/pgsql-general/2006-03/msg00891.php Feel free to submit an additional doc comment. -- Robert Treat Build A Brighter Lamp :: Linux Apache {middleware} PostgreSQL ---------------------------(end of broadcast)--------------------------- TIP 2: Don't 'kill -9' the postmaster
