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Oracle OCP IZ0-053 Q157(DB_BLOCK_CHECKING)

原创 Oracle 作者:abstractcyj 时间:2016-03-10 15:44:36 0 删除 编辑
157.The DB_BLOCK_CHECKING initialization parameter is set to OFF. Which block checking would be
performed?
A. The Oracle database will perform block checking for the index blocks only
B. The Oracle database will not perform block checking for any of the data blocks
C. The Oracle database will perform block checking for the default permanent tablespace only
D. The Oracle database will perform block checking for the data blocks in all user tablespaces
E. The Oracle database will perform block checking for the data blocks in the SYSTEM tablespace only
Answer: E


http://docs.oracle.com/cd/E11882_01/server.112/e40402/initparams048.htm#REFRN10029

DB_BLOCK_CHECKING specifies whether or not Oracle performs block checking for database blocks.

Values:

  • OFF or FALSE

    No block checking is performed for blocks in user tablespaces. However, semantic block checking for SYSTEM tablespace blocks is always turned on.

  • LOW

    Basic block header checks are performed after block contents change in memory (for example, after UPDATE or INSERT statements, on-disk reads, or inter-instance block transfers in Oracle RAC).

  • MEDIUM

    All LOW checks and full semantic checks are performed for all objects except indexes (whose contents can be reconstructed by a drop+rebuild on encountering a corruption).

  • FULL or TRUE

    All LOW and MEDIUM checks and full semantic checks are performed for all objects.


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曾从事java方向开发多年。近年已经转入数据库方向。主要擅长SQL优化,Oracle数据库问题诊断,Oracle备份与恢复等。服务于医药物流,医院等行业

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