Oracle 视图 MAP_OBJECT 官方解释，作用，如何使用详细说明
本站中文解释
Oracle视图MAP_OBJECT被定义为一种可以表达对象之间的映射关系的数据库对象。它用于表示在两个或多个表中，存在相同的内容。MAP_OBJECT可以用来定义一个映射，并表示每个元组之间的关联性。映射可以是一个简单的一对一映射，也可以是一个复杂的多对一映射。
使用MAP_OBJECT时，可以在应用程序中为表提供灵活的数据模型。MAP_OBJECT可以把多个表中的数据通过“对应表”联系起来，提高了查询的性能。它还能简化用户访问多个表的工作，减少了定义应用程序的复杂性。
官方英文解释
MAP_OBJECT is a global temporary table that displays the hierarchical arrangement of storage containers for objects. Each row in the table represents a level in the hierarchy.
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Name of the object |
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Owner of the object |
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Object type |
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File index (corresponds to |
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Element depth within the I/O stack |
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Index corresponding to the element |
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Contiguous set of logical blocks of the file (in HKB units) that is resident contiguously on the element |
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Number of HKB between contiguous units (CU) in the file that are contiguous on this element. Used in RAID5 and striped files. |
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Number of contiguous units that are adjacent to each other on this element that are separated by STRIDE HKB in the file. In RAID5, the number of contiguous units also include the parity stripes. |
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Element offset (in HKB units) |
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Offset (in HKB units) from the start of the file to the first byte of the contiguous units |
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Data type ( |
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Position of the parity. Only for RAID5. This field is needed to distinguish the parity from the data part. |
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Parity period. Only for RAID5. |
