In the RDBS, catalogs name is usually referred when the catalogs query is acting in the table by the means of SQL.
在RDBS中，利用SQL语句进行表的相关查询时，通常都是利用相关名的说法来解释。
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。
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.
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。
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