索引的层次和惟一性也会影响数据的访问速度。
The level and uniqueness of an index will also affect the speed of accessing data.
索引的创建有助于避免对表进行不必要的扫描和排序，加速频繁执行的查询以及确保惟一性。
Creating indexes helps avoid unnecessary table scans and sorts, speeds up frequently executed queries, and ensures uniqueness.
搜索、视图、惟一性和索引。
ccd表中必须有惟一性约束——可以通过主键或者源表或ccd表上的惟一索引实现。
Uniqueness in the CCD table must be enforced — either by a primary key or unique index on the source table or CCD table.
首先在逻辑上将表与其自身连接，然后将更具有选择性的非起始索引键作为索引绑定过滤器，应用于起始键值的每个惟一的组合。
The table is logically joined to itself, and the more selective non-leading index keys are applied as index bound filters to each unique combination of the leading key values.
索引的惟一性是指一个索引拥有多少个重复键。
The uniqueness of index refers to how many duplicate keys an index has.
如果在一个类中的多个属性上定义惟一性，那么应该创建一个包含所有这些属性的索引。
If you define uniqueness on multiple attributes within a class, create one index that includes all the attributes.
定义惟一索引的索引规范还将关于索引列惟一性的信息传递给联邦系统。
An index specification that defines a unique index also conveys information about the uniqueness of the index columns to the federated system.
用以读取叶子页面的成本取决于索引的大小、查询的筛选器以及索引的惟一性。
The costs used to find a leaf page depends on the size of the index, the filer of the query, and the uniqueness of the index.
用以读取叶子页面的成本取决于索引的大小、查询的筛选器以及索引的惟一性。
The costs used to find a leaf page depends on the size of the index, the filer of the query, and the uniqueness of the index.
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