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Oracle

1Z0-062 · Question #244

Automatic Shared Memory Management (ASMM) is enabled for your database instance. You execute the following command: SQL> ALTER SYSTEM SET DB_CACHE_SIZE = 100M; Which statement is true?

The correct answer is A. It succeeds and the minimum size for the DEFAULT buffer pool is set to 100M. When Automatic Shared Memory Management (ASMM) is enabled, setting DB_CACHE_SIZE using ALTER SYSTEM SET will succeed, but it functions as a minimum size for the default buffer pool rather than a fixed allocation.

Managing the Database Instance

Question

Automatic Shared Memory Management (ASMM) is enabled for your database instance. You execute the following command:

SQL> ALTER SYSTEM SET DB_CACHE_SIZE = 100M; Which statement is true?

Options

  • AIt succeeds and the minimum size for the DEFAULT buffer pool is set to 100M.
  • BIt fails because DB_CACHE_SIZE is a static initialization parameter.
  • CIt fails because ASMM is enabled and individual SGA components cannot be sized.
  • DIt succeeds and the value is changed in the SPFILE immediately, but the change takes effect

How the community answered

(43 responses)
  • A
    81% (35)
  • B
    2% (1)
  • C
    5% (2)
  • D
    12% (5)

Why each option

When Automatic Shared Memory Management (ASMM) is enabled, setting `DB_CACHE_SIZE` using `ALTER SYSTEM SET` will succeed, but it functions as a minimum size for the default buffer pool rather than a fixed allocation.

AIt succeeds and the minimum size for the DEFAULT buffer pool is set to 100M.Correct

With Automatic Shared Memory Management (ASMM) enabled, `DB_CACHE_SIZE` becomes a lower bound for the buffer cache, allowing ASMM to dynamically allocate more if needed. The `ALTER SYSTEM SET DB_CACHE_SIZE = 100M` command successfully establishes 100M as the minimum allocation for the default buffer pool.

BIt fails because DB_CACHE_SIZE is a static initialization parameter.

DB_CACHE_SIZE is a dynamic initialization parameter, meaning its value can be changed using `ALTER SYSTEM` while the instance is running.

CIt fails because ASMM is enabled and individual SGA components cannot be sized.

Even with ASMM enabled, individual SGA components like `DB_CACHE_SIZE` can be sized, but they serve as minimums or maximums, allowing ASMM to manage the rest dynamically.

DIt succeeds and the value is changed in the SPFILE immediately, but the change takes effect

The command succeeds and the value is changed immediately in memory (and the SPFILE if `SCOPE=BOTH` or `SCOPE=SPFILE` is active), meaning the change takes effect without delay, not at some future point.

Concept tested: ASMM and DB_CACHE_SIZE behavior

Source: https://docs.oracle.com/en/database/oracle/oracle-database/21/admin/managing-memory.html#GUID-862D19D8-A299-47F1-A896-1F5FC994D541

Topics

#Automatic Shared Memory Management (ASMM)#SGA sizing#DB_CACHE_SIZE#initialization parameters

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