PostgreSQL doesn’t support marking table columns as unused. ALTER TABLE EMPLOYEES DROP UNUSED COLUMNS įor more information, see CREATE TABLE in the Oracle documentation. SELECT * FROM USER_UNUSED_COL_TABS ĭrop the column permanently (physically drop the column).
To set a column as unused, use the SET UNUSED clause.Įxamples ALTER TABLE EMPLOYEES SET UNUSED (COMMISSION_PCT) ĪLTER TABLE EMPLOYEES SET UNUSED (JOB_ID, COMMISSION_PCT) ĭisplay unused columns. To overcome this issue, a column can be marked as unused and then be physically dropped later. The main advantage of setting a column to UNUSED is to reduce possible high database load when dropping a column from a large table. Select statements don’t retrieve data from columns marked as unused and aren’t displayed when running a DESCRIBE table command. Unused columns aren’t physically dropped, but are treated as if they were dropped. Oracle provides a method to mark columns as unused. PostgreSQL doesn’t support unused columns.
