因为这两个视图都是在下面的表格上使用单独的SQL选择语句进行定义，所以不会影响查询性能。
Because both of these views are defined with a single SQL select statement on the underlying table, the query performance will not suffer.
如果您不再想在这个表格的任何一个域上激活不能区分大小写查询程序，您可以使整个表格的索引功能失效。
If you no longer want to enable case-insensitive queries on any field in the table, you can disable indexes for the entire table.
如果表格有一定数量的片段键(或者分区键)值，而且在片段键上有同等谓词的表格上查询时，它会很有用处。
It is useful when a table has a finite set of values for the fragment key (or partitioning key) and queries on the table have an equality predicate on the fragment key.
例如，一个Oracle用户可以选择“从user _ tables选择表格名”-这是一个查询，绝不能失败-除非该连接实际上是坏的。
For example an oracle user might choose "select table_name from user_tables" - which is a query that should never fail - unless the connection is actually bad.
例如，一个Oracle用户可以选择“从user _ tables选择表格名”-这是一个查询，绝不能失败-除非该连接实际上是坏的。
For example an oracle user might choose "select table_name from user_tables" - which is a query that should never fail - unless the connection is actually bad.
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