Following example shows what happens when locks are disabled on the TABLE.

-- disable lock on a table
SQL> alter table t disable table lock;
Table altered.

-- shows one can’t drop table as table locks are disable
SQL> drop table t;
drop table t
*
ERROR at line 1:
ORA-00069: cannot acquire lock — table locks disabled for T

-- shows one can’t truncate table as table locks are disable
SQL> truncate table t;
truncate table t
*
ERROR at line 1:
ORA-00069: cannot acquire lock — table locks disabled for T

-- DML is okay to run
SQL> delete from t;
1 row deleted.

-- new columns can be added
SQL> alter table t add tt varchar2(1);
Table altered.

-- columns can’t be modified
SQL> alter table t modify tt varchar2(10);
alter table t modify tt varchar2(10)
*
ERROR at line 1:
ORA-00069: cannot acquire lock — table locks disabled for T

-- columns can’t be dropped
SQL> alter table t drop column tt;
alter table t drop column tt
*
ERROR at line 1:
ORA-00069: cannot acquire lock — table locks disabled for T

-- enable locking on the table
SQL> alter table t enable table lock;
Table altered.

-- table now can be dropped
SQL> drop table t;
Table dropped.

• General DBA