1.测试准备

----从1分15秒优化到31秒

----create public database link dblinkname connect to username identified by passwd using 'tnsname';

----select count(1) from user_tables@dl_11g2;

----SQL> set timing on

----SQL> create table t_zhong as select * from t_news_info@qianlong_link where 1=2;

Table created.

Elapsed: 00:00:00.13

---- truncate table t_zhong;

----SQL> set autot off

----SQL> drop table t_zhong purge;

----SQL> set autot trace stat

SQL> insert into t_zhong select * from qdata.T_NEWS_INFO@qianlong_link where seq>10400000;

114747 rows created.

Elapsed: 00:26:31.62

Statistics

----------------------------------------------------------

973  recursive calls

453767  db block gets

67045  consistent gets

29  physical reads

428009340  redo size

837  bytes sent via SQL*Net to client

837  bytes received via SQL*Net from client

3  SQL*Net roundtrips to/from client

58  sorts (memory)

0  sorts (disk)

114747  rows processed

SQL> create table t_test1 as select * from t_zhong where 1=2;

SQL> insert into t_test1 select * from t_zhong;

114747 rows created.

Elapsed: 00:01:15.87

Statistics

----------------------------------------------------------

214  recursive calls

303118  db block gets

95308  consistent gets

25749  physical reads

427150268  redo size

843  bytes sent via SQL*Net to client

794  bytes received via SQL*Net from client

3  SQL*Net roundtrips to/from client

1  sorts (memory)

0  sorts (disk)

114747  rows processed

SQL> truncate table t_test1;

SQL> analyze table t_test1 compute statistics;

SQL> analyze table t_zhong compute statistics;

SQL> select TABLE_NAME, BLOCKS , EMPTY_BLOCKS from dba_tables where table_name='T_TEST1';

TABLE_NAME                         BLOCKS EMPTY_BLOCKS

------------------------------ ---------- ------------

T_TEST1                                 0            7

SQL> select TABLE_NAME, BLOCKS , EMPTY_BLOCKS from dba_tables where table_name='T_ZHONG';

TABLE_NAME                         BLOCKS EMPTY_BLOCKS

------------------------------ ---------- ------------

T_ZHONG                             21968          559

2.优化之前插入测试

SQL>  set timing on

SQL>  set autot trace stat

SQL> insert into t_test1 select * from t_zhong;

114747 rows created.

Elapsed: 00:01:15.21

Statistics

----------------------------------------------------------

217  recursive calls

303099  db block gets

95226  consistent gets

47717  physical reads

427226232  redo size

844  bytes sent via SQL*Net to client

794  bytes received via SQL*Net from client

3  SQL*Net roundtrips to/from client

1  sorts (memory)

0  sorts (disk)

114747  rows processed

SQL> truncate table t_test1;

3.优化1：将表修改为nologging

----设置表或索引为nologging，执行dml操作时就不会产生大量的redo咯

------注意：nologging在归档模式下有效，非归档下不起作用。库处在FORCE LOGGING模式下，此时的nologging方式是无效的

SQL> set autot  off

SQL> select owner,table_name,TABLESPACE_NAME,LOGGING,BLOCKS,EMPTY_BLOCKS from dba_tables where table_name='T_TEST1;

SQL> select NAME,LOG_MODE,OPEN_MODE,FORCE_LOGGING from v$database;

NAME      LOG_MODE     OPEN_MODE            FOR

--------- ------------ -------------------- ---

ORCL      ARCHIVELOG   READ WRITE           NO

SQL> select table_name,logging from dba_tables where table_name='T_TEST1';

TABLE_NAME                     LOG

------------------------------ ---

T_TEST1                        YES

SQL> alter table t_test1 nologging;

 

SQL> select table_name,logging from dba_tables where table_name='T_TEST1';

TABLE_NAME                     LOG

------------------------------ ---

T_TEST1                        NO

SQL> set autot trace stat

SQL> insert into t_test1 select * from t_zhong;

114747 rows created.

Elapsed: 00:01:01.21

Statistics

----------------------------------------------------------

209  recursive calls

303076  db block gets

95257  consistent gets

47719  physical reads

427269008  redo size

845  bytes sent via SQL*Net to client

794  bytes received via SQL*Net from client

3  SQL*Net roundtrips to/from client

1  sorts (memory)

0  sorts (disk)

114747  rows processed

SQL> truncate table t_test1;

SQL> alter table t_test1 logging;

SQL> insert /*+nologging*/ into t_test1 select * from t_zhong;

4.优化2：将索引修改为nologging

select owner,index_name,index_type,table_name,logging,status from dba_indexes where table_name='T_ZHONG';

select * from dba_ind_columns where table_name='T_ZHONG';

select * from dba_objects where object_name='SYS_IL0000088940C00001$$';

SQL> select index_name, index_type，table_name,logging from dba_indexes where table_name='T_ZHONG';

INDEX_NAME          INDEX_TYPE   TABLE_NAME                     LOG

----------                     ------------             -------- ---

SYS_IL0000088940C00001$$       LOB   T_ZHONG                        YES

----注意，lob字段索引不能alter和drop，所以也就不能做nologging操作咯

----如果有索引可以设置nologging

alter index ind_name nologging;

----如果可以，可以直接删除索引，insert之后在重建

5.优化3：插入的采用append方式

SQL> truncate table t_test1;

----增加hint /*+append*/ 表示不用在高水位下查找可insert的空间，直接在高水位之上插入

SQL>  insert /*+append*/ into t_test1 select * from t_zhong;

114747 rows created.

Elapsed: 00:00:49.75

Statistics

----------------------------------------------------------

297  recursive calls

128430  db block gets

71998  consistent gets

47650  physical reads

255286784  redo size

833  bytes sent via SQL*Net to client

807  bytes received via SQL*Net from client

3  SQL*Net roundtrips to/from client

1  sorts (memory)

0  sorts (disk)

114747  rows processed

SQL> truncate table t_test1;

SQL> insert /*+append nologging*/ into t_test1 select * from t_zhong;

Elapsed: 00:00:46.72

a、非归档模式下，只需append就能大量减少redo的产生；归档模式下，只有/*+append nologging*/ 才能大量减少redo。

b、insert /*+ append */ 时会对表加锁（排它锁），会阻塞表上的除了select以外所有DML语句；传统的DML在TM enqueue上使用模式3（row exclusive），其允许其他DML在相同的模式上获得TM enqueue。但是直接路径加载在TM enqueue使用模式6（exclusive），这使其他DML在直接路径加载期间将被阻塞。

c、insert /*+ append */ 直接路径加载，速度比常规加载方式快。因为是从HWM的位置开始插入，也许会造成空间浪费。

6.优化4：采用parallel并行

SQL> truncate table t_test1;

----增加hint /*+parallel(tab,4)*/ 增加之前最好先开启会话并行 alter session enable/disable parallel dml;  表示充分利用系统硬件资源

----如果disable关闭并行会话时报ORA-12841错误，那就先做commit或者rollback在关闭并行

SQL> insert /*+parallel(t_test1,2)*/ into t_test1 select * from t_zhong;

114747 rows created.

Elapsed: 00:01:07.09

Statistics

----------------------------------------------------------

216  recursive calls

303106  db block gets

95170  consistent gets

47718  physical reads

427238808  redo size

848  bytes sent via SQL*Net to client

818  bytes received via SQL*Net from client

3  SQL*Net roundtrips to/from client

1  sorts (memory)

0  sorts (disk)

114747  rows processed

SQL> truncate table t_test1;

SQL> alter session enable parallel dml;

SQL> insert /*+parallel(t_test1,2)*/ into t_test1 select * from t_zhong;

Elapsed: 00:01:03.46

SQL> truncate table t_test1;

SQL> insert /*+append parallel(t_test1,2)*/ into t_test1 select * from t_zhong;

Elapsed: 00:00:52.04

------另外在插入后面跟的select查询语句，也可以进行优化，比如加一下hint /*+paralle*/等等。    加parallel的hint来提高其并发，这里需要注意的是最大并发度受到初始化参数parallel_max_servers的限制，并发的进程可以通过v$px_session查看，或者ps -ef |grep ora_p查看。

7.优化5：增大sort_area或PGA

show parameter sort_area_size

----检查sort_area_size初始大小为:65536  默认64k。以字节为单位

查看workarea_size_policy的值

SQL> show parameter workarea_size_policy

NAME                                 TYPE        VALUE

------------------------------------ ----------- ------------------------------

workarea_size_policy                 string      AUTO

设置workarea_size_policy的值

----SQL> alter system set workarea_size_policy=MANUAL scope=spfile;

System altered.

设置sort_area_size的值

----SQL> alter system set sort_area_size=65535000 scope=spfile;

System altered.

重启db service生效。

-------这里不修改系统参数，只是在会话中调整

----注意，这里的table还是处于nologging模式

SQL>  truncate table t_test1;

SQL> alter session set workarea_size_policy=manual;

SQL> alter session set sort_area_size=50240000;    ----改为50m

SQL> insert into t_test1 select * from t_zhong;

114747 rows created.

Elapsed: 00:00:44.15

SQL>  truncate table t_test1;

SQL>  insert /*+parallel*/ into t_test1 select * from t_zhong;

114747 rows created.

Elapsed: 00:00:43.06

SQL>  truncate table t_test1;

SQL>  insert /*+append*/ into t_test1 select * from t_zhong;

114747 rows created.

Elapsed: 00:00:39.85

SQL>  truncate table t_test1;

SQL>  insert /*+append parallel(t_test1,2)*/ into t_test1 select * from t_zhong;

114747 rows created.

Elapsed: 00:00:35.44

SQL> truncate table t_test1;

SQL>  insert /*+append parallel*/ into t_test1 select * from t_zhong;

114747 rows created.

Elapsed: 00:00:33.39

SQL>  truncate table t_test1;

SQL>  insert /*+append nologging*/ into t_test1 select * from t_zhong;

114747 rows created.

Elapsed: 00:00:31.79

SQL>  truncate table t_test1;

SQL>  insert /*+append nologging parallel*/ into t_test1 select * from t_zhong;

114747 rows created.

Elapsed: 00:00:29.72

----未开归档的情况下，最快貌似能达到21秒

Elapsed: 00:00:21.05

reference    http://blog.itpub.net/26736162/

http://blog.csdn.net/wyzxg/article/

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