ASA Database Administration Guide
  Database Options
    Alphabetical list of options

BLOCKING option [database]

Function 

Controls the behavior in response to locking conflicts.

Allowed values 

ON, OFF

Scope 

Can be set for an individual connection or for the PUBLIC group. Takes effect immediately.

Default 

ON

Description 

If BLOCKING is ON, any transaction attempting to obtain a lock that conflicts with an existing lock held by another transaction waits until every conflicting lock is released. At that time, the write goes through. If BLOCKING is OFF, the transaction that attempts to obtain a conflicting lock receives an error.

For more information, see Two-phase locking.