抓出必须创建索引的列
以下脚本以来统计信息的准确性：
select column_name,
num_rows,
Cardinality,
selectivity,
histogram,
num_buckets, 'Consider create index on this column' as notice
from (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_buckets
from dba_tab_col_statistics a, dba_tables b
where a.owner = b.owner
and a.table_name = b.table_name
and a.owner = 'SCOTT'
and a.table_name = 'TEST')
where selectivity >= 10
and column_name not in (select column_name
from dba_ind_columns
where table_owner = 'SCOTT'
and table_name = 'TEST')
and column_name in
(select c.name
from sys.col_usage$ u, sys.obj$ o, sys.col$ c, sys.user$ r
where o.obj# = u.obj#
and c.obj# = u.obj#
and c.col# = u.intcol#
and r.name = 'SCOTT'
and o.name = 'TEST');