相关子查询将极大地降低数据检索的速度，对于拥有几百万个行但没有索引的大型表的非选择性查询更是如此。
Correlated subqueries will greatly degrade the speed of data retrieval, especially for non-selective queries on huge tables with millions of rows and with no index.
以上示例展示了如何使用连续扫描和索引来进行数据检索，以及如何使用嵌套循环连接方法来连接所有表。
The above example shows that sequential scan and indexes are used to do the data retrieval, and the nested-loop join method is used to join all tables.
它包括所使用的索引、从数据库表检索字段的时间和执行查询的步骤次序。
It includes the indexes that are used, The Times at which fields are retrieved from the database tables, and the order of the steps that execute the query.
如果查询从一个表检索大量数据，优化器就不会使用索引。
The optimizer won't use an index if the query retrieves a large amount of data from a table.
xslt样式表为字典编制索引、查找与nlsid属性值匹配的密钥、与字典中的当前语言匹配并检索已翻译的文本。
The XSLT style sheet indexes into the dictionary, finds the key that matches the value of the nlsid attribute, matches the current language in the dictionary, and retrieves the translated text.
JDBC适配器使用 object_key作为对客户表的索引，以检索更改的行。
The JDBC adapter uses the object_key as an index into the Customer table to retrieve the changed row.
在数据库服务器使用所有表筛选器之后，从外部表检索出的行数将很少，而内部表具有一个可用于执行连接的索引。
The number of rows retrieved from the outer table after the database server applies any table filters is small, and the inner table has an index that can be used to perform the join.
它包括所使用的索引、从数据库表中检索字段的次数，以及执行查询的步骤的顺序。
It includes the indexes that are used, The Times at which fields are retrieved from the database tables, and the order of steps in which the query is executed.
DB 2可以使用关系索引和xml索引来快速检索所关注的数据，避免了盲目地扫描表中的所有行。
DB2 can use both the relational and XML indexes to quickly pinpoint the data of interest, avoiding a costly scan of all rows in the table.
这样设计，参与索引的表和列的数据不得不从SQLServer运送到全文检索服务。
With this design, data from tables and columns to be indexed have to be shipped from SQL Server to the Full Text Search service.
QueryQ5对谓词使用索引表，但是需要提取函数（具有XML分析）来检索客户电子邮件地址。
Query Q5 uses side tables for the predicates, but requires an extract function (with XML parsing) to retrieve the customers email addresses.
设计了一种XML索引表数据结构，使得检索空间大幅缩减。
And a data structure of XML index table was designed to reduce the search space greatly.
通过实际构建系统，探讨了基于混合索引的中文全文检索系统的实现。图3。表4。参考文献5。
By actual examples, the authors discuss the realization of a Chinese full-text retrieval system based on mixed indexing. 3 figs. 4 tabs. 5 refs.
如果您通过表的行索引或列索引检索值，将无法设置返回值。
If you retrieve the value by means of the table's row index or column index, you will not be able to set the return value.
如果您通过表的行索引或列索引检索值，将无法设置返回值。
If you retrieve the value by means of the table's row index or column index, you will not be able to set the return value.
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