• 053-008


    8.Which statement is true regarding online redefinition for the migration of BasicFile LOBs to SecureFile LOBs?
    A. It cannot be done in parallel.
    B. It can be done at the table level or partition level.
    C. It does not require additional storage because the operation is done online.
    D. Local and global indexes are maintained automatically during the operation.
    Answer: B

    解析:
    Online Redefinition for BasicFiles

    Online redefinition is the only recommended method for migration of BasicFile LOBs to SecureFiles. It can be done at the table or partition level.
    参考:
    http://docs.oracle.com/cd/B28359_01/appdev.111/b28393/adlob_smart.htm

    You can modify LOB storage with an ALTER TABLE statement or with online redefinition by using the DBMS_REDEFINITION package. If you have not enabled LOB encryption, compression, or deduplication at create time, Oracle recommends that you use online redefinition to enable them after creation, because this process is more disk-space efficient for changes to these three parameters.

    BasicFiles LOB 与 SecureFiles 区别

    1. SecureFiles是11G才支持,BasicFiles 是10G就开始支持

    BASICFILE

    When the compatibility mode is set to 10g, the LOB storage clause is identical to that used in 10g (keyword BASICFILE is not valid). When the 11g compatibility mode (or greater) is set, the original, pre-11.1 release LOB functionality is enabled by default and this parameter is specified for completeness.

    SECUREFILE

    To use the SecureFiles LOB storage architecture and functionality, explicitly specify the storage parameter SECUREFILE. A SecureFiles LOB can only be created in a tablespace managed with Automatic Segment Space Management (ASSM,非ASSM表空间将以BasicFile存储).

    For BasicFiles LOBs, specifying any of the SecureFiles LOB options results in an error.

    2. 一些性能方面的差异

    可变 trunk 等,详细参考:

    http://wenku.baidu.com/view/cb71ab6448d7c1c708a14512

  • 相关阅读:
    Win10下 Docker Flask实例
    4.1 线性映射的概念
    桥梁的基本组成和分类
    Qt5字符串编码转换学习
    在右键菜单中添加用Jupyter Notebook打开
    左右手(直角)坐标系叉乘计算公式
    __new__方法与单键实例
    向量组的秩
    从线性组合的角度理解三维运算
    Hexo使用小结
  • 原文地址:https://www.cnblogs.com/bowshy/p/3675906.html
Copyright © 2020-2023  润新知