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.
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。
By internal statistics, I mean the statistics in the system catalogs that the optimizer USES to determine the lowest-cost query execution plan.
而在关系语言中，这种查询需要进行也许跨越了多个数据表和系统目录表的联接。
In a relational language, such a query would require a join that might span several data tables and system catalog tables.
优化程序采用系统目录，说明那里有多少行，以及构造了较好的索引来计算所采用的查询路径。
The optimizer uses system catalogs indicating how many rows there are and how well the indexes are formed to figure out what query path to use.
所以，在程序开始遍历这些文件的时候，假设为了确定目录的总大小，就必须逐一重新查询文件系统。
So when the program starts to loop through the files, perhaps to determine the directories overall size, it has to requery the file system one by one.
当优化器创建查询计划时，它将使用下列系统目录信息。
The optimizer USES the following system catalog information as it creates a query plan.
要查看是否对数据库执行了RUNSTATS，一种快捷方法便是查询一些系统目录表。
One quick way to see whether RUNSTATS has been performed on your database is to query some system catalog tables. For example, as shown in the script above, you can run this command.
此命令更新了系统目录中的统计数据，优化程序使用这些数据来确定成本最低的查询计划。
This command updates the statistics in the system catalogs that the optimizer USES to determine the lowest-cost query plan.
DB 2优化器然后查询存储在DB 2系统目录中的系统信息和统计信息，以确定完成满足SQL请求所必需的任务的最佳方法。
The DB2 optimizer then queries system information and statistics stored in the DB2 system catalog to determine the best method of accomplishing the tasks necessary to satisfy the SQL request.
当你删除存储在计算机上的文件时，这些数据并没有真正移除，它们的信息被保存在操作系统可以查询到的目录中。
When it comes to data stored on your computer, deleting files doesn't actually remove the data.
当你删除存储在计算机上的文件时，这些数据并没有真正移除，它们的信息被保存在操作系统可以查询到的目录中。
When it comes to data stored on your computer, deleting files doesn't actually remove the data.
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