Which three resources are managed using global concurrency control in an Oracle 19c RAC multi-instance database? (Choose three.)
Which three resources are managed using global concurrency control in an Oracle 19c RAC multi-instance database? (Choose three.)
In an Oracle 19c RAC multi-instance database, global concurrency control is necessary to manage resources that can be accessed by different instances. The three resources managed using global concurrency control are: Database block buffers, which are managed by cache fusion to ensure consistency across instances; Enqueues, which control resource access to prevent conflicts; and Cursors, which are controlled by global locks to ensure proper access across instances. Latches and mutexes are mainly used for intra-instance concurrency control, not on a global scale across multiple instances.
correct answers B,D,E beacuse; Latches and mutexes may only protect access to memory structures if they are accessed by processes in the same instance. In RAC, latches and mutexes are still used, but for global concurrency control, some additional global enqueues are used to provide protection across instances. Oracle requires concurrency control because it is a multi-user system. Single-instance Oracle provides concurrency control: Latches or mutexes for memory structures Enqueues for resource control Buffer cache pins for cache management
Proposed answer is an concept error: mutexes and latches are "intra" instance concurrency control mechanisms. The question is about global concurrency control. RAC course guide page 7-3 states Single-instance oracle provides concurrency control through: - latches or mutexes for memory structures - enqueues for resource control - buffer cache pins for cache management In RAC, structures and resources may be accessed by or modified by a ssession running on any database instance RAC, therefore, requires additional global concurrency controls to mediate access across instances - global locks control library and row cache access --> (cursors) - Global enqueues control resource access - Cache fusion controls buffer cache access --> (database block buffers) So correct answer is: AEF
I think ACE
considering global concurrency control , AEF
I think B,D and E
https://www.dba-oracle.com/real_application_clusters_rac_grid/rac_process.htm
AEF Since the RAC system allows many users to connect and process database SQL operations concurrently, many resources, such as data blocks and enqueues, are used simultaneously. This situation demands an effective synchronization of the concurrent tasks.
BDE or ADE i think BDE