Global Enqueue Services

GES coordinates the requests of all global enqueues (any non-buffer cache resources). This is the single point of contact for lock management in the Oracle RAC. It is also involved in deadlock detection and request timeouts. During normal operation, it manages caching and performs the cleanup operation during cluster reconfiguration.

Latches and Enqueues

The two types of local locks are latches and enqueues. Latches are instance specific and do not affect database-wide operations. Latches do not affect the global operations of clustered environments. Enqueues, however, can be both local to an instance and global to a cluster.

Latches are lightweight, low-level serialization mechanisms that protect in-memory data structures ...

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