Oracle 性能调优学习笔记(十五)-- 应用调优

  表迁移(非分区表)
      1.权限和约束将被保持.
      2.表结构发生变化.
      3.迁移数据到其他表空间.
     alter table scott.emp move tablespace train;
     索引可能失效.
    
     重新定义online表的信息
     1.修改表的存储参数
     2.支持并行查询
     3.添加和删除分区
     4.表空间的移动.
     5.重建表减少碎片.
     6.更改一个表的信息.
     7.添加或者删除列
    
   压缩索引:
      1.create index emp_last_name_idx
        on scott.emp
     (last_name) cmpress;
      2.重建索引压缩
                 alter index emp_last_name_idx
                    rebuild compress ;
               
                analyze index t_idx validate structure;
    
    1.创建索引
    create index t_idx on t(owner,object_type,object_name) compress 2;
    备注: compress 2表示压缩2列
    
    2.分析索引
     analyze index t_idx validate structure;
    3.查看索引统计信息
     select name,height,lf_blks,br_blks,btree_space,opt_cmpr_count,
     opt_cmpr_pctsave from index_stats;
    
    
    
    
    
   倒序索引
    1.create unique index emp_idx on emp(epno)
        reverse pctfree 30
     storage (initial 200k
               next 200k
         pctincrease 0
         maxextents 50
         )
     tablespace tbs_index;
       2.alter  unique index emp_idx  rebuild reverse;   
   
   bitmap index
       create bitmap index dep_idx
    on dept(mgr_id)
    storage(
     initial 200k
     next 200k
     pctincrease 0
     maxextents 50
    )tablespace tbs_idx;
    
    索引组织表
       有点:
          快速基于主的访问表的数据.
       减少必要的存储.
      
       缺点:必须有主键
            不能被集群
         
       创建IOT表
           create table country
     ( country_id int,
       country_name varchar(25),
       constraint country_id_pk primary key(country_id)
     )organization index
     pctthreshold 20
     overflow tablespace users;
     
     查询IOT表的信息
       select table_name,iot_name,iot_type
         from dba_tables;
       select index_name ,index_type,tablespace_name ,table_name
                        from dba_indexes;
                      select segment_name,tablespace_name,segment_type
            from dba_segments;
      
            Mapping table
        create table country
        (
         country_id char(2),
         contry_name varchar(20),
         constraint country_id_pk
         primary key(country_id)
        )
        organization index
        mapping table tablespace users;
       
       
        select index_name ,pct_direct_access
           from dba_indexes
         where pct_direct_access is not null;
        
    analyze 语句
        1.validate structure;
                           analyze table scott.emp validate structure;
                    2.list chained rows
               
    Data WareHouse
         1.db_file_multiblock_read_count: