||Oracle Tips by Burleson
Oracle10g Grid Computing
Chapter 12 - RAC Design Considerations
Disabling Table Locks for Individual Tables
attempting to lock tables with disabled locks receive an error. To
re-enable table locking, use the following statement:
table_name ENABLE TABLE LOCK
syntax forces all currently executing transactions to commit before
enabling the table lock. The statement does not wait for new
transactions to start after issuing the ENABLE statement. The
disadvantage to this statement is that it must be executed for all
tables that may experience improper locking.
whether a table in the schema has its table lock enabled or disabled,
query the table_lock column in the user_tables data dictionary table.
If select privilege is on dba_tables, then the table lock state of
other user’s tables can be queried as well. Use the all_tables views
to see the locking state of tables for which you have been granted
Setting dml_locks to Zero
dml_locks initialization parameter, table locks can be set for an entire
instance. This will disable the DROP TABLE, create INDEX, and LOCK
TABLE commands. If these commands are not needed, then set dml_locks
to zero to minimize lock conversions and achieve maximum performance.
DDL statements cannot be executed against tables with disabled locks.
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