DB 2fori 6.1最近的一个增强使得理解在SQL性能监视器中sql语句级使用优化器成为可能。
A recent enhancement to DB2 for I 6.1 makes it possible to understand the optimizer use at the SQL statement level within the SQL Performance Monitor.
使用优化器可以基于PD F中的静态项(标签、行)在表单中创建新交互项(复选框、字段)，并对齐表单中的现有项(标签或字段)。
The optimizers are targeted to create new interactive items (check boxes, fields) on the form based on static items (labels, lines) on the PDF and align existing items (labels or fields) on the form.
这已经是一个较好的值，因为它可以保证优化器在使用分位数统计信息的情况下对确定过滤因子的估计误差最大只有5%。
This is already a good value because it guarantees that the optimizer, by using the quantile statistics, only has an estimated maximum error of 5% for the determined filter factors.
如果IN列表中包含参数标记符或主机变量，使优化器不能使用编目统计信息来确定选择性，就会出现这种情况。
This can occur if the IN list contains parameter markers or host variables which prevent the optimizer from using catalog statistics to determine the selectivity.
这里我们解释您应该做些什么，以便让DB 2优化器选择使用一个空间索引。
Here we explain what you have to do to give the DB2 optimizer the choice to use a spatial index.
如果无法避免执行计划中出现的问题，那么可以使用准则来影响优化器计划，从而解决性能问题。
If the execution plan problems cannot be avoided, guidelines can be used to affect the optimizer plan to mitigate the performance problems.
当以连接的形式使用in谓词时，优化器将仍会考虑为它检测统计关联。
When the in predicate is used in its join form, the optimizer still considers it for statistical correlation detection.
为使优化器能够使用可用的分布统计信息，带有具体值的谓词极为重要。
Predicates with concrete values are important for the optimizer to be able to use available distribution statistics.
例如，优化器必须确定是否应使用索引。
For example, the optimizer must determine whether indexes should be used.
此决策实际取决于优化枚举器之前如何使用函数以及应如何对函数进行大量测试。
This decision really depends on how the function is used and should be heavily tested prior to optimizing the enumerator.
数据联合模式的功能可以通过使用数据相关的技术(如优化器或补偿)或自己开发的应用程序来实现。
The functionality of the data federation pattern can be implemented using either database-related technologies such as optimizer or compensation, or by home-grown applications.
如果您在查询中使用实际值，那么优化器将能够基于真实值来计算评估值。
When you use the actual value in the query, the optimizer will be able to calculate the estimation based on the real value.
注意：当索引表达式被用于关系表达式，或作为某个操作符类函数的参数时，查询优化器将考虑使用函数索引。
Note: the query optimizer considers using a functional index when the index expression is used in a relational expression or as an argument to one of the operator class functions.
您还研究了参数标记/主变量的使用会为DB2优化器对分布统计信息的考虑带来怎样的限制。
You have also examined how the use of parameter markers/host variables may limit the consideration of distribution statistics by the DB2 optimizer.
优化器将决定是否可以使用索引来评估筛选器。
The optimizer will decide whether an index can be used to evaluate a filter.
如果向查询提供数据的后端数据源断开了，并且优化器选择使用MQT来满足查询，那么查询将会执行。
If a back-end data source that provides data to a query is down and the optimizer chooses to satisfy the query using MQTs, the query will be executed.
优化器然后使用复合索引将临时表连接到事实表，来快速定位在维度表中满足条件的行。
The optimizer will then join that temp table to the fact table using the compound index to quickly locate the rows that satisfy the criteria on the dimension tables.
注意：优化器不会对下面这个查询使用函数索引。
Note: Here is a query for which the optimizer cannot consider using the functional index.
该参数值较高可能会影响优化器在缓冲池使用中对比较保守的存取方案的选择。
Higher values for this parameter can influence the optimizer to choose access plans that are more conservative in buffer pool usage.
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.
下面是优化器为表空间所使用的重要信息。
The important information used by the optimizer for a tablespace is the following.
在下列情况下，优化器将使用索引。
DISABLEQUERYOPTIMIZATION'子句可以用来防止优化器考虑使用特定的MQT。
The 'DISABLE QUERY OPTIMIZATION' clause may be used to prevent the optimizer from considering use of a particular MQT.
WebSphereFederationServer使用它的基于成本的优化器，确定检索和处理数据的最佳路径。
WebSphere Federation Server USES its cost based optimizer in order to determine the optimal access path to retrieve and process the data.
Runstat ——收集优化器所使用的统计数据
在这种情况下，优化器会使用一个通用规则或者默认值以正常数据分布率来评估得到一个平均开销值。
In this case, the optimizer USES a generic rule or a default value to estimate an average cost by assuming normal data distribution.
对于带变量的sql语句，优化器会使用一个默认过滤因子在绑定时确定最佳访问路径。
For SQL statements with variables, the optimizer USES a default filter factor to determine the best access path at bind time.
将该组索引输入到基于成本的优化器，这个优化器决定是否使用任何合适的索引。
This set is input to the cost-based optimizer that decides whether to use any of the eligible indexes or not.
可以使用以下命令告诉优化器不要使用任何优化配置文件。
You can use the following command to tell the optimizer to not use any optimization profile.
可以使用以下命令告诉优化器不要使用任何优化配置文件。
You can use the following command to tell the optimizer to not use any optimization profile.
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