这种实现风格有助于消除重复的数据并(在许多情况下通过联合)提供一致的主数据访问路径。
This implementation style is useful to remove duplicates and provide (in many cases federated) a consistent access path to master data.
不管哪种模式(3nf或Star)，Teradata查询优化器依赖于统计信息帮助确定最佳数据访问路径。
Regardless of schema (3nf or Star), the Teradata query optimizer relies on statistics to help it determine the best way to access data.
如果应用程序中的所有数据访问路径都被执行，那么捕获的信息将包含向数据库发出的完整sql语句列表。
If all the data access paths in the application are executed, then the captured information contains the complete list of SQL statements that are issued to the database.
从性能的角度来看，一个良好表现的访问路径相对于最终的结果集应该触及最少的数据量。
From a performance point of view, a good performing access path should touch the least amount of data with respect to the final result set.
本节的其余部分再一次以数据流的观点向您介绍访问路径图以便您可以在查询执行的性能方面获得充分的理解。
The rest of this section takes you through the access path graph one more time from the data flow perspective so that you can gain a full understanding of the performance aspect of query execution.
即使表的行数保持一致，使用由RUNSTATS更新的统计信息来更改数据内容可以产生不同的、也许更好的访问路径。
Even if the number of rows in a table remains consistent, changes in data contents can result in different, and hopefully better, access paths using statistics updated by RUNSTATS.
SQL编译器使用信息约束将语句转化成更优的形式，从而改善对所需数据的访问路径。
The SQL compiler USES them to transform a statement into a more optimized form, thus improving the access path to the required data.
如果编目中没有列数据值分布信息，DB 2就会假设值是均匀分布的，这可能导致优化器选择非最优的访问路径。
Without column data-value distribution information in the catalog, DB2 will assume an even distribution of values, which may lead the optimizer to a sub-optimal access path.
访问路径图不但描述“操作细节”，而且描述数据如何流动。
An access path graph not only describes the "operational details" of query execution, it also describes how the data flows.
请记住，优化器使用编目数据决定访问路径。
Keep in mind that this catalog data is what the optimizer USES to make access path decisions.
Soft RI结合统计数据使得优化器能够生成更有效的访问路径。
Soft RI in conjunction with statistics may enable the optimizer to generate a more efficient access path.
这就说明我可能有一个低效的访问路径，DB 2读取的数据比应该读取的数据更多。
This tells me that I may have an inefficient access path, where DB2 reads more data than it should.
尽管DB 2优化器对选择最佳访问路径有所帮助，但结果还是依赖于输入数据，优化器无法访问或控制这些数据。
Although the DB2 optimizer is helpful for selecting the best access path, the result depends on the input data, which is often not accessed or controlled by the optimizer.
数据从下往上流动(如访问路径图所示)并通过访问路径图上的操作节点处理。
Data flows from the bottom up (as displayed in the graph) and is processed by operation nodes in the access path graph.
访问计划描述访问路径，这些路径是DB 2优化器为sql语句访问数据而选择的。
Access plan describes the access path that the DB2 optimizer has chosen for accessing data for an SQL statement.
在选择数据的访问路径时，如果没有正确的列分布统计数据，DB 2可能没有足够的信息来做出最佳的选择，尤其是如果数据出现严重误差。
Without correct column distribution statistics, DB2 may not have enough information to make the best choice when choosing an access path to the data-especially if data is heavily skewed.
恰当的访问路径意味着一个索引可用并且已使用，所以该索引能够方便地对该数据进行访问。
An appropriate access path means that an index is available and used so that the index drives the access to the data.
具体表现就是提前执行一些工作，比如确定数据库访问路径。
It does this by performing some work ahead of time, such as determining the database access path.
DB 2中的静态SQL是一个强大的功能，可以通过预先执行某些工作来简化运行时的数据访问，例如确定数据库访问路径。
Static SQL in DB2 is a powerful capability that can streamline data access at run time by doing some of the work ahead of time, such as determining the database access path.
不充分或不准确的统计数据会导致对候选访问路径评估不准确，这也是选择低效访问路径的最常见原因。
Insufficient or inaccurate statistics lead to inaccurate cost estimates for the candidate access paths and is the most common reason for the selection of inefficient access paths.
不一致的统计数据还会误导优化器选择糟糕的访问路径。
The inconsistent statistics may also mislead the optimizer into choosing a bad access path.
集中工具终止安全数据中心中特定主机上的管理访问路径，这随后将利用中介传递通过轻量级客户机(如浏览器)进行的访问。
Central tools terminate that administrative access path onto specific hosts in a secured data center, which then mediate access through a lightweight client, such as a browser.
如本文开头所提到的，统计数据是优化器作出关于访问路径的决策的基础。
As was mentioned at the beginning of this article, database statistics are the facts on which the optimizer makes decisions about access plans.
如果统计数据已更改一段时间，并且您的当前语句拥有理想的访问路径，DB 2将基于旧语句继续使用该路径。
If statistics haven't changed in a while and you have a desirable access path with current stats, DB2 will continue to use that path based on the old stats.
丢失的统计数据会让优化器高估或低估谓词的选择性，最终会选择低效的访问路径。
Missing statistics can cause the optimizer to overestimate or to underestimate the selectivity of a predicate, and eventually to select an inefficient access path.
准确而全面的统计数据能帮助生成良好的访问路径建议，当然，索引advisor工具执行时要有准确的统计数据。
Accurate and complete statistics will help drive good access path advice, and of course the index advisor should not be executed without good statistics.
统计数据advisor工具：收集所需统计数据以完成访问路径的建议。
Statistics advisor: recommendations for collecting the required statistics to facilitate access path selection.
为了建立高效地访问路径提出了一种XML数据的结构索引，并介绍了利用结构索引实现基本的数据操作的方法。
In order to establish efficient access path, the authors put forward a structure index for XML data, and introduce a method of implementing operations based on structure index.
为了建立高效地访问路径提出了一种XML数据的结构索引，并介绍了利用结构索引实现基本的数据操作的方法。
In order to establish efficient access path, the authors put forward a structure index for XML data, and introduce a method of implementing operations based on.
为了建立高效地访问路径提出了一种XML数据的结构索引，并介绍了利用结构索引实现基本的数据操作的方法。
In order to establish efficient access path, the authors put forward a structure index for XML data, and introduce a method of implementing operations based on.
应用推荐