信息约束可以很好地辅助查询优化。
Informational constraints can be a great aid to query optimization.
这一部分包含了查询优化及方案优化。
This section covers query optimization and schema optimization.
对联邦查询优化作一个概述。
查询优化涉及到了怎样改进慢速查询的问题。
Query optimization concerns how to improve the performance of slow queries.
使用提示、解释计划和分析的查询优化特性。
Query optimization features using hints, explain plans, and profiling.
现在我们来谈谈关于二级缓存的查询优化问题。
Now let us discuss the issue with the query optimization for the objects which are configured for second level cache.
与此同时，查询优化策略注重尽可能减少页面读取。
Meanwhile, query optimization tactics focused on minimizing page fetches wherever possible.
查询优化器不会自动重新计算表的配置文件。
The query optimizer does not recalculate the profile for tables automatically.
联合服务器还必须提供查询优化功能，以最高效地响应请求。
The federation server must also provide query optimization capabilities in order to respond to the request most efficiently.
查询优化器将尝试减少发送到数据源的消息的数量。
The query optimizer will try to reduce the number of messages sent to the data source.
查询优化器根据从每个表检索的行数估计查询成本。
The query optimizer bases query-cost estimates on the number of rows to be retrieved from each table.
在为查询生成计划的过程中，查询优化器与非关系包装器通信。
During plan generation for the query, the query optimizer communicates with the non-relational wrapper.
按照查询优化器建议的键创建逻辑文件能够执行得更快。
Can perform faster with the creation of a keyed logical file containing the keys suggested by the query optimizer?
这些视图包括一些包含对查询优化器有用的统计信息的列。
These views include columns containing statistical information that is useful to the query optimizer.
下推的决定是包装器在计划阶段与查询优化器一起做出的。
The push-down decision is made by the wrapper during the planning phase, while working with the query optimizer.
大型缓冲池还会对查询优化产生影响，因为更多的工作可在内存中完成。
Large buffer pools also have an effect on query optimization, since more of the work can be done in memory.
通常，查询优化器选择将在最短时间内返回整个结果集的计划。
In general, the query optimizer selects a plan that will return the entire result set in the shortest amount of time.
可以使用REOPT指南，将查询优化推迟到运行时输入变量已知的时候。
You can defer query optimization until input variables are known at runtime with the REOPT guideline.
REOPT绑定选项将查询优化推迟到OPEN时有可用输入变量的时候。
The REOPT bind option defers query optimization until input variable values are available at OPEN time.
注册表的值又确定在查询优化期间将使用何种类型的刷新延迟物化查询表。
The value of the register in turn determines what types of refresh deferred materialized query tables will be used during query optimization.
有了这个特性，查询优化器可以在决定访问计划时立即考虑索引。
With this feature, the query optimizer can immediately consider the index when determining an access plan.
如果网络较慢，查询优化器还尝试减少发送到数据源的消息数量。
The query optimizer also tries to reduce the number of messages sent to the data source if the network is slow.
查询优化类用于在编译SQL查询时指导优化器使用不同的优化级别。
The query optimization class is used to direct the optimizer to use different degrees of optimization when compiling SQL queries
该信息允许快速识别模型和查询优化，应用该优化的目的是达到更好的性能。
This information permits the rapid identification of model and query optimizations which could be applied in order to achieve better performance.
准确的索引信息和统计信息是查询优化器中基于成本的决策的基础。
Accurate index information and statistics are fundamental to cost-based decisions in the query optimizer.
查询优化器的一项新特性支持一种新的索引扫描，即索引自连接路径。
A new feature of the query optimizer supports a new type of index scan, called an index self-join path.
REOPT ONCE：查询执行中只发生一次查询优化，即在查询第一次执行时。
REOPT once: query optimization occurs once at query execution time, when the query is executed for the first time.
查询功能是产品的一个便捷特性，但它不受高端数据库中所有高级查询优化器的支持。
The query functionality is a valid convenience feature of the product, but it is not backed by all the sophisticated query optimizers found in top-end databases.
如果有了准确的统计信息，那么查询优化器一般能够得出正确的选择性估计。
Given accurate statistics, the query optimizer generally comes up with correct selectivity estimates.
RUNSTATS实用程序用于更新系统目录表中的统计信息，以帮助查询优化过程。
The RUNSTATS utility updates statistics in the system catalog tables to help with the query optimization process.
应用推荐