IBM Db2 11.1 Certification Guide

Explicit Hierarchical Locking 

Explicit Hierarchical Locking (EHL) is designed to eliminate data sharing costs for tables and partitions that are only accessed by a single member in a pureScale cluster. You can activate the EHL feature by running the following UPDATE DATABASE CFG command:

UPDATE DB CFG FOR <DBNAME> USING opt_direct_wrkld YES; 

This parameter, when set to AUTOMATIC, will cause the EHL to only be activated when both cf_gbp_sz and cf_lock_sz are set to AUTOMATIC.

The EHL state changes, based on the table or partition access, are as follows:

• Entering into the NOT_SHARED state:
• An INSERT, UPDATE, DELETE, and SELECT operation on a table
• A data partition in a range partition table can enter NOT_SHARED state while the base table ...