摘要: 1.查询表的基数及选择性 select a.column_name, b.num_rows, a.num_distinct cardinality, round( a.num_distinct/b.num_rows*100,2) selectivity, a.histogram, a.num_buc 阅读全文
posted @ 2020-07-20 11:14 orcl 阅读(131) 评论(0) 推荐(0) 编辑