Re: ALTER TABLE DROP COLUMN

> The Hermit Hacker <scrappy@hub.org> writes:
> > hrmm .. mvcc uses a timestamp, no?  is there no way of using that
> > timestamp to determine which columns have/haven't been cleaned up
> > following a crash?  maybe some way of marking a table as being in a 'drop
> > column' mode, so that when it gets brought back up again, it is scan'd for
> > any tuples older then that date?  
> 
> WAL would provide the framework to do something like that, but I still
> say it'd be a bad idea.  What you're describing is
> irrevocable-once-it-starts DROP COLUMN; there is no way to roll it back.
> We're trying to get rid of statements that act that way, not add more.
> 
> I am not convinced that a 2x penalty for DROP COLUMN is such a huge
> problem that we should give up all the normal safety features of SQL
> in order to avoid it.  Seems to me that DROP COLUMN is only a big issue
> during DB development, when you're usually working with relatively small
> amounts of test data anyway.
> 

Bingo!

--  Bruce Momjian                        |  http://candle.pha.pa.us pgman@candle.pha.pa.us               |  (610)
853-3000+  If your life is a hard drive,     |  830 Blythe Avenue +  Christ can be your backup.        |  Drexel Hill,
Pennsylvania19026