Ravi Krishna <srkrishna@xxxxxxxxx> writes: >> VACUUM would not change the state of the dropped columns. > When does it change? Never, unless you drop and recreate the table. Removing a dropped column would change the attnums of following columns, which we can't support because the tableoid+attnum is the only persistent identifier of a column. (From memory, operations like VACUUM FULL and CLUSTER will rewrite dropped columns with NULLs to reduce their storage impact. But they don't go away.) regards, tom lane
