Oracle

The SET UNUSED Option

Figo Kim 2006. 12. 1. 17:05

SET UNUSED / DROP UNUSED COLUMNS

ALTER TABLE     <table_name>

SET UNUSED    (<column_name>);

Or


ALTER TABLE    <table_name>

SET UNUSED COLUMN    <column_name>;


ALTER TABLE    <table_name>

DROP UNUSED COLUMNS;


* DROP UNUSED COLUMNS : removes from the table all columns currently makred as unused.
  • Does not actually remove the target columns.
  • Does not restore the disk space used by these columns.
  • DROP will be faster than a normal Dropping.
  • Related data dictionary view : USER_UNUSED_TABS