RUNSTATS with system page-level sampling.
带有系统页级抽样的runstats。
Compared with no sampling, page-level sampling significantly improves performance.
与不进行抽样相比，页级抽样极大地提高了性能。
Page level sampling reduces I/O significantly since it reads only a percentage of the data pages.
而页级的抽样则可以显著减少I/O，因为它只读取一定百分比的数据页。
Some examples of RUNSTATS using Bernoulli row-level and system page-level sampling are as follows.
下面是一些使用贝努里(Bernoulli)行级和系统页级抽样的RUNSTATS例子。
But, row level sampling may produce more accurate statistics if relational data values are highly clustered.
但是，如果关系数据值是高度聚集的，那么行级抽样可以产生更精确的统计信息。
System page-level sampling is similar to row-level sampling, except that the pages are sampled and not rows.
系统页级抽样与行级抽样类似，除了抽样的对象是页面而不是行。
Row level sampling reads all data pages but considers only a percentage of the rows on each page, and therefore only a subset of the corresponding XDA pages.
行级的抽样读取所有数据页，但是只考虑每页上一定百分比的行，因此只包含相应xda页面中的一部分。
Methods Using multi-level sampling method, 638 subjects were selected randomly and surveyed. The serological specimens from 638 subjects were separated and detected using haemoglutinin inhibition(HI).
方法采用多阶段抽样方法，随机抽取638名调查对象进行个案调查并采集血液标本分离血清，用血凝抑制（HI）方法对标本进行检测。
Methods Using multi-level sampling method, 638 subjects were selected randomly and surveyed. The serological specimens from 638 subjects were separated and detected using haemoglutinin inhibition(HI).
方法采用多阶段抽样方法，随机抽取638名调查对象进行个案调查并采集血液标本分离血清，用血凝抑制（HI）方法对标本进行检测。
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