Thomas Lockhart <thomas@fourpalms.org> writes:
> istm that the general strategy for changing column types would require
> marking a column as dead and adding a new column to replace it, or
> writing an atomic copy / modify / replace operation for tables which
> modifies tuples as it proceeds, or ?? Just because we may allow a hack
> for text types because they happen to have a similar/identical storage
> structure doesn't necessarily mean that it is a good design for the
> general case.
Sure. This is not intended to cover the general case; if we hold Chris
to that standard then the task will drop right back to the TODO list
where it's been for years. My thought was that we've frequently
answered people on the mailing lists "well, officially that's not
supported, but unofficially, for the case you need you can hack the
catalogs like this: ...". Why not make that folklore functionality
available in a slightly cleaner package? It won't preclude doing a
full-up ALTER COLUMN implementation later.
regards, tom lane