查询用户的索引

select index_name,
       table_name,
       tablespace_name,
       index_type,
       uniqueness,
       status
  from dba_indexes
 where owner = '<用户名>';

查询用户的索引列

select index_name,
       table_name,
       column_name,
       index_owner,
       table_owner
  from dba_ind_columns
 where table_owner = '<用户名>';

查看索引的各种初始化因子

select index_name,
       table_name,
       tablespace_name,
       pct_free,
       pct_increase,
       initial_extent,
       next_extent,
       status
  from dba_indexes
 where owner = '<用户名>';

重建和维护索引

alter index scott.emp_ename_idx rebuild
pctfree 40
storage (next 300k);

查看索引segment

select segment_name, segment_type, tablespace_name, extents
  from dba_segments
 where owner = '<用户名>'
   and segment_type = 'INDEX';

给索引添加相应的extent

alter index scott.emp_ename_idx allocate extent;

回收索引端

alter index scott.emp_ename_idx deallocate unused;

合并索引碎片

alter index scott.emp_ename_idx coalesce;

联机重建索引

alter index scott.emp_ename_idx rebuild online;

标识索引的使用情况

1. 启用索引监控

alter index emp_ename_idx monitoring usage;

生成启用索引监控语句：

select 'alter index ' || owner || '.' || index_name || ' monitoring usage;'
  from dba_indexes
 where owner = '<用户名>';

2. 执行相关查询

select ename, job, sal
  from scott.emp
 where ename like 'C%';

3. 查看索引是否使用

select * from v$object_usage;

4. 禁用索引监控

alter index emp_ename_idx nomonitoring usage;

生成禁用索引监控语句：

select 'alter index ' || owner || '.' || index_name || ' nomonitoring usage;'
  from dba_indexes
 where owner = '<用户名>';