Evaluate the query execution plan.
评估查询的执行计划。
Step 2.1: Examine the query execution plan.
步骤2.1：检查查询执行计划。
The query execution plan can be viewed using the db2exfmt tool
这个查询执行计划可以使用db2exfmt工具查看
Illustrates how to interpret a federated query execution plan.
阐释如何解释联邦查询执行计划。
You can use the output of Visual Explain or db2exfmt to obtain the query execution plan.
您可以使用VisualExplain或db 2 exfmt的输出来获得查询执行计划。
You can analyze the query execution plan output to decide whether or not this is necessary.
您可以分析查询执行计划输出，以确定这是否是必需的。
According to the overall query execution plan, the sub operations are then applied at the sources.
根据总体查询执行计划，将随后对数据源执行各个子操作。
The output of the query optimizer on a federated system is the Federated Query Execution Plan (FQEP).
联邦系统上查询优化器的输出是联邦查询执行计划（FederatedQuery Execution Plan，FQEP）。
The main database configuration parameter settings that affect the query execution plan were set as follows
影响查询执行计划的主要数据库配置参数设置如下
Section explains and section actuals are very powerful features to investigate problems with a query execution plan.
在研究查询执行计划的问题时，片段解释和片段实绩是非常强大的特性。
Now take a look at the three new operators and how they work together with XML indexes in a query execution plan.
现在看一下这三个新操作符，以及它们与xml索引在执行计划中是如何工作的。
At this step, you need to dig into the statistics you collected above and take a good look at the query execution plan.
在这一步中，需要挖掘上面所收集的统计数据，并仔细查看查询执行计划。
This method cuts down query plan search space greatly, thus ensures the quality of parallel query execution plans.
这种优化方法大大地缩减了查询执行计划空间，确保了并行查询执行计划的优化性。
The optimizer relies on statistics to properly cost alternative query execution plans (QEPs) and choose the most optimal plan.
优化器是依靠统计信息来计算可选查询执行计划（QEP）的开销，同时选择出最优的计划。
And when I check on the SQL query execution plan, it seems to be pretty inconsistent in how SQL tries to optimize this query.
当我检查的SQL查询执行计划，这似乎是很不一致的方式试图优化这个查询的SQL。
So we added indexes on those joining columns and from the following query execution plan, we can see the query cost is greatly reduced.
因此，我们在这些连接列上添加了索引，从下列查询执行计划中我们可以看到，查询成本减少了很多。
"Dynamic" means that the query is sent into the database engine as a string; it must be parsed and have a query execution plan generated.
“动态”意味着查询作为字符串发送给数据库引擎；必须对它进行解析，并生成查询执行计划。
By internal statistics, I mean the statistics in the system catalogs that the optimizer USES to determine the lowest-cost query execution plan.
通过内部统计数据，我指的是系统目录中的统计数据，优化器可以确定最低成本的查询执行计划。
From version 9.3 on, there is a nice enhancement of this utility; you can get the detailed query execution plan without ever executing the query.
从版本9.3开始，该实用程序得到了较好的提高；您可以获取详细的查询执行计划，而不必执行该查询。
For SELECT queries, the text of the remote SQL statement can be found in the details associated with the SHIP operator in the query execution plan.
对于SELECT查询，远程sql语句中的文本可以在查询执行计划中与SHIP操作符相关的细节中找到。
The action begins when an application sends a query to the appliance host server, which compiles the query and creates an optimized query execution plan.
当应用程序向设备的主机服务器发送一个查询时，处理流程开始。 主机服务器将编译该查询并创建一个优化的查询执行计划。
Both statistical views and REOPT allow the optimizer to compute a more accurate cardinality estimate and consequently choose an optimal query execution plan.
统计视图和REOPT都使优化器可以计算出更精确的基数估计，而后选择一个最佳查询执行计划。
When this option is set, the query optimizer chooses the query execution plan that pushes the most work down to the data source as indicated by the PDA component.
当设置了该选项时，查询优化器选择按照PDA的指示将大部分工作下推到数据源的查询执行计划。
The search space of parallel query execution plan is exponential complexity. How to prune the search space efficiently is the key problem of parallel query optimization.
并行查询执行计划的搜索空间里指数级增长，如何高效地裁剪搜索空间是并行查询优化的关键所在。
The query optimizer might come up with a different query execution plan tailored to provide good performance for fast retrieval of first 'n' rows rather than all the result rows.
查询优化器可能得出一个不同的查询执行计划，这个计划可以专门为最快地获取前'N '行，而不是所有结果行提供良好的性能。
For the exceptional situations where the optimizer cannot choose an optimal query execution plan, DB2 has added features such as the SELECTIVITY clause and optimization guidelines.
对于优化器不能选择最佳查询执行计划的例外情况，DB 2已经增加了诸如selectivity子句和优化指南之类的特性。
Informix server will then generate a file named sqexplain.out in your user home directory which will record the detailed query execution plan and its costs as we talked about above.
然后，Informix服务器将在用户home目录中生成一个名为sqexplain . out的文件，正如上面谈到的，其中将记录详细的查询执行计划及其成本。
Like other relational database management systems such as Oracle and SQL Server, Informix has its internal optimizer, which is responsible for selecting the best query execution plan.
与Oracle和SQLServer等其他关系数据库管理系统一样，Informix也有内部优化器，负责选择最佳的查询执行计划。
When an application submits a query to the federated system, the federated server identifies the relevant data sources, and develops a query execution plan for obtaining the requested data.
当应用程序向联邦系统提交一个查询时，联邦服务器识别相关数据源，并生成一个用于获得被请求数据的查询执行计划。
When the asynchrony feature of WFS 9.1 is enabled by setting the appropriate configuration parameters, the query execution plan for the UNION ALL query illustrated above may look like this.
当通过设置适当的配置参数启用WFS 9.1中的异步特性时，前面演示的UNIONALL查询的查询执行计划如下。
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