"Markus Bertheau" <[EMAIL PROTECTED]> writes: > I basically want to change a boolean column to char. The boolean > column has a default of true. The char column should have 'f' for > false and 't' for true. I think that an SQL statement like the > following should work, but it doesn't:
Hmm ... the way I would have expected to work is alter table posts alter column deleted drop default, alter column deleted type char(1) using (case when deleted then 't' else 'f' end), alter column deleted set default 'f'; but that does not work either --- you have to do it in more than one command: begin; alter table posts alter column deleted drop default; alter table posts alter column deleted type char(1) using (case when deleted then 't' else 'f' end), alter column deleted set default 'f'; commit; We could fix this by tweaking ATPrepCmd to schedule drop-default subcommands in an earlier pass than alter-type, and set-default subcommands afterwards. However I think the way it's done now was chosen to avoid surprising behavior in corner cases like alter table foo alter column bar set default ..., alter column bar drop default; You'd expect this to leave you with no default, but with the change the DROP part would be re-ordered to occur first. So maybe the cure is worse than the disease. OTOH that's a pretty silly example, whereas wanting to ALTER TYPE and fix the default in a single command is quite reasonable. Thoughts? regards, tom lane ---------------------------(end of broadcast)--------------------------- TIP 9: In versions below 8.0, the planner will ignore your desire to choose an index scan if your joining column's datatypes do not match