Summary
In production systems changes are often allowed only during special maintenance times, and changes such as DDL to change table/index structures must be prohibited at other times. To disable DDL for a table execute
ALTER TABLE TABLE_NAME DISABLE TABLE LOCK;
This will prevent for example
altering the table, or doing a
truncate, but
select/update/insert will continue working. To enable back DDL execute
ALTER TABLE TABLE_NAME ENABLE TABLE LOCK;
