Find Oracle RAC Locks
Oracle Database Tips by Donald Burleson
Oracle RAC is extremely complex and special
scripts are required to identify locks within any RAC cluster.
The monitoring of the RAC global enqueue services (GES) process is
performed using the gv$enqueue_stat
For full scripts, download the
Oracle script collection.
Also see these scripts for
finding RAC blocking sessions.
The RAC resources managed by the GES include the following
- It is acquired in the exclusive mode when a transaction initiates
its first row level change. The lock is held until the transaction is
committed or rolled back.
Library Cache locks
- When a RAC database object (such as a table, view, procedure,
function, package, package body, trigger, index, cluster, or synonym)
is referenced during parsing or compiling of a SQL, DML or DDL,
PL/SQL, or Java statement, the process parsing or compiling the
statement acquires the library cache lock in the correct mode.
Dictionary Cache Locks
- Global enqueues are used in the cluster database mode. The data
dictionary structure is the same for all Oracle instances in a cluster
database, as it is for instances in a single-instance database.
script collection contains a complete list of Oracle RAC locking
scripts, but this script can be used to quickly identify and isolate
RAC locking issues: