实验环境
搭建平台：VMware Workstation
OS：RHEL 6.10
Grid&DB：Oracle 11.2.0.4
SQL参考select c.sql_id, c.sql_text, b.index_name, e.table_name, trunc(d.num_distinct / e.num_rows * 100, 2) selectivity, d.num_distinct, e.num_rows from v$sql_plan a, (select * from (select index_owner, index_name, table_owner, table_name, column_name, count(*) over(partition by index_owner, index_name, table_owner, table_name) cnt from dba_ind_columns) where cnt = 1) b, v$sql c, dba_tab_col_statistics d, dba_tables e where a.object_owner = b.index_owner and a.object_name = b.index_name and b.index_owner = 'TEST' and a.access_predicates is not null and a.sql_id = c.sql_id and a.child_number = c.child_number and d.owner = e.owner and d.table_name = e.table_name and b.table_owner = e.owner and b.table_name = e.table_name and d.column_name = b.column_name and d.table_name = b.table_name and d.num_distinct / e.num_rows < 0.1; --找出选择性小于10%的SQL
