[20120809]学习物化视图(补充).txt

[20120809]学习物化视图(补充).txt
1.测试环境:
SQL> select * from v$version ;
BANNER
--------------------------------------------------------------------------------
Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - 64bit Production
PL/SQL Release 11.2.0.1.0 - Production
CORE    11.2.0.1.0      Production
TNS for Linux: Version 11.2.0.1.0 - Production
NLSRTL Version 11.2.0.1.0 - Production
create table sales as select * from sh.sales;
insert into sales select * from sales;
insert into sales select * from sales;
insert into sales select * from sales;


CREATE MATERIALIZED VIEW LOG ON "SCOTT"."SALES" WITH ROWID, SEQUENCE ("CHANNEL_ID","AMOUNT_SOLD")  INCLUDING NEW VALUES;


drop MATERIALIZED VIEW SCOTT.MV1;


CREATE MATERIALIZED VIEW SCOTT.MV1


 REFRESH FAST on commit 


 WITH ROWID


 enable QUERY REWRITE AS


 SELECT SCOTT.SALES.CHANNEL_ID C1,


 SUM("SCOTT"."SALES"."AMOUNT_SOLD") M1,


 COUNT("SCOTT"."SALES"."AMOUNT_SOLD") M2,


 COUNT(*) M3


 FROM SCOTT.SALES


 GROUP BY SCOTT.SALES.CHANNEL_ID;




2.开始测试:


SQL> set timing on


SQL> select channel_id,sum(amount_sold),count(*) from sales group by channel_id;


CHANNEL_ID SUM(AMOUNT_SOLD)   COUNT(*)


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


         2        210770739    2064200


         4        109654416     947328


         3        463002086    4322624


         9       2219410.08      16592


Elapsed: 00:00:00.00


SQL> @dpc


PLAN_TABLE_OUTPUT


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


SQL_ID  crucrsdqdrm0b, child number 0


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


select channel_id,sum(amount_sold),count(*) from sales group by


channel_id


Plan hash value: 2958490228


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


| Id  | Operation                    | Name | E-Rows | Cost (%CPU)|


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


|   0 | SELECT STATEMENT             |      |        |     3 (100)|


|   1 |  MAT_VIEW REWRITE ACCESS FULL| MV1  |      4 |     3   (0)|


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


Note


-----


   - Warning: basic plan statistics not available. These are only collected when:


       * hint 'gather_plan_statistics' is used for the statement or


       * parameter 'statistics_level' is set to 'ALL', at session or system level




20 rows selected.


Elapsed: 00:00:00.02


--可以发现由于使用了物化视图,执行很快!


3.修改记录看看


回话1执行如下(不提交):


SQL1> update sales set amount_sold=amount_sold*1 where rownum


1 row updated.




回话2执行如下:


SQL2> select channel_id,sum(amount_sold),count(*) from sales group by channel_id;


CHANNEL_ID SUM(AMOUNT_SOLD)   COUNT(*)


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


         2        210770739    2064200


         4        109654416     947328


         3        463002086    4322624


         9       2219410.08      16592


SQL2> @dpc


PLAN_TABLE_OUTPUT


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


SQL_ID  crucrsdqdrm0b, child number 0


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


select channel_id,sum(amount_sold),count(*) from sales group by


channel_id


Plan hash value: 2958490228


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


| Id  | Operation                    | Name | E-Rows | Cost (%CPU)|


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


|   0 | SELECT STATEMENT             |      |        |     3 (100)|


|   1 |  MAT_VIEW REWRITE ACCESS FULL| MV1  |      4 |     3   (0)|


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


Note


-----


   - Warning: basic plan statistics not available. These are only collected when:


       * hint 'gather_plan_statistics' is used for the statement or


       * parameter 'statistics_level' is set to 'ALL', at session or system level


20 rows selected.


--由于没有提交,回话执行访问mview.


回到回话1执行:


SQL1> select channel_id,sum(amount_sold),count(*) from sales group by channel_id;


CHANNEL_ID SUM(AMOUNT_SOLD)   COUNT(*)


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


         2        210770739    2064200


         4        109654416     947328


         3        463002086    4322624


         9       2219410.08      16592


Elapsed: 00:00:01.94


SQL1> @dpc


PLAN_TABLE_OUTPUT


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


SQL_ID  crucrsdqdrm0b, child number 1


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


select channel_id,sum(amount_sold),count(*) from sales group by


channel_id


Plan hash value: 2895541888


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


| Id  | Operation          | Name  | E-Rows | Cost (%CPU)|  OMem |  1Mem | Used-Mem |


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


|   0 | SELECT STATEMENT   |       |        |  9972 (100)|       |       |          |


|   1 |  HASH GROUP BY     |       |      4 |  9972   (4)|   899K|   899K| 2757K (0)|


|   2 |   TABLE ACCESS FULL| SALES |   7350K|  9734   (1)|       |       |          |


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


--可以发现,这种方式由于事务没有提交,mview也无法刷新,这种仅仅通过访问sales获得结果.


--这样访问时间变长.接着提交事务.


SQL1> commit;


SQL1> select channel_id,sum(amount_sold),count(*) from sales group by channel_id;


CHANNEL_ID SUM(AMOUNT_SOLD)   COUNT(*)


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


         2        210770739    2064200


         4        109654416     947328


         3        463002086    4322624


         9       2219410.08      16592


Elapsed: 00:00:01.88


SQL> @dpc


PLAN_TABLE_OUTPUT


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


SQL_ID  crucrsdqdrm0b, child number 1


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


select channel_id,sum(amount_sold),count(*) from sales group by


channel_id


Plan hash value: 2895541888


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


| Id  | Operation          | Name  | E-Rows | Cost (%CPU)|  OMem |  1Mem | Used-Mem |


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


|   0 | SELECT STATEMENT   |       |        |  9972 (100)|       |       |          |


|   1 |  HASH GROUP BY     |       |      4 |  9972   (4)|   899K|   899K|  850K (0)|


|   2 |   TABLE ACCESS FULL| SALES |   7350K|  9734   (1)|       |       |          |


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


--奇怪,一旦出现这种情况后,执行计划不再访问物化视图.切换回话2执行.


SQL2> set timing on


SQL2> select channel_id,sum(amount_sold),count(*) from sales group by channel_id;


CHANNEL_ID SUM(AMOUNT_SOLD)   COUNT(*)


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


         2        210770739    2064200


         4        109654416     947328


         3        463002086    4322624


         9       2219410.08      16592


Elapsed: 00:00:01.88


--回话2也一样,执行计划不再访问物化视图.


SQL2> select MVIEW_NAME,LAST_REFRESH_TYPE,LAST_REFRESH_DATE from user_mviews;


MVIEW_NAME                     LAST_REF LAST_REFRESH_DATE


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


MV1                            FAST     2012-08-09 15:55:39


Elapsed: 00:00:00.00


4.再修改记录并且commit看看.不再重复问题同上.


SQL1> select channel_id,sum(amount_sold),count(*) from sales group by channel_id;


CHANNEL_ID SUM(AMOUNT_SOLD)   COUNT(*)


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


         2        210770739    2064200


         4        109654416     947328


         3        463002086    4322624


         9       2219410.08      16592


Elapsed: 00:00:01.81


SQL1> select MVIEW_NAME,LAST_REFRESH_TYPE,LAST_REFRESH_DATE from user_mviews;


MVIEW_NAME                     LAST_REF LAST_REFRESH_DATE


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


MV1                            FAST     2012-08-09 16:01:19


SQL1> select sql_id,child_number,sql_text from v$sql where sql_id='crucrsdqdrm0b';


SQL_ID        CHILD_NUMBER SQL_TEXT


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


crucrsdqdrm0b            1 select channel_id,sum(amount_sold),count(*) from sales group by channel_id


Elapsed: 00:00:00.00


--可以发现仅仅存在child_number=1. child_number=0的不存在了.难道物化视图没刷新,还是有问题?


5.修改语句如下:


select channel_id,sum(amount_sold),count(*) from sales group by channel_id;


为


Select channel_id,sum(amount_sold),count(*) from sales group by channel_id;


SQL1> Select channel_id,sum(amount_sold),count(*) from sales group by channel_id;


CHANNEL_ID SUM(AMOUNT_SOLD)   COUNT(*)


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


         2        210770739    2064200


         4        109654416     947328


         3        463002086    4322624


         9       2219410.08      16592


Elapsed: 00:00:00.00


SQL1> @dpc


PLAN_TABLE_OUTPUT


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


SQL_ID  aykmr2yy598f0, child number 0


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


Select channel_id,sum(amount_sold),count(*) from sales group by


channel_id


Plan hash value: 2958490228


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


| Id  | Operation                    | Name | E-Rows | Cost (%CPU)|


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


|   0 | SELECT STATEMENT             |      |        |     3 (100)|


|   1 |  MAT_VIEW REWRITE ACCESS FULL| MV1  |      4 |     3   (0)|


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


--我仅仅改变一个字母,由于这条语句第1次执行没有在shared pool.可以发现可以使用物化视图.


6.接着重复试验看看.


SQL1> update sales set amount_sold=amount_sold*1 where rownum


SQL1> commit;


SQL1> Select channel_id,sum(amount_sold),count(*) from sales group by channel_id;


SQL> CHANNEL_ID SUM(AMOUNT_SOLD)   COUNT(*)


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


         2        210770739    2064200


         4        109654416     947328


         3        463002086    4322624


         9       2219410.08      16592


Elapsed: 00:00:00.00


--只要没有出现在DML的rollback/commit前,该sql语句就没有问题.


6.刷新shared pool看看.


SQL> alter system flush shared_pool;


System altered.


Elapsed: 00:00:00.23


SQL> select channel_id,sum(amount_sold),count(*) from sales group by channel_id;


CHANNEL_ID SUM(AMOUNT_SOLD)   COUNT(*)


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


         2        210770739    2064200


         4        109654416     947328


         3        463002086    4322624


         9       2219410.08      16592


Elapsed: 00:00:00.14


SQL> @dpc


PLAN_TABLE_OUTPUT


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


SQL_ID  crucrsdqdrm0b, child number 0


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


select channel_id,sum(amount_sold),count(*) from sales group by


channel_id


Plan hash value: 2958490228


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


| Id  | Operation                    | Name | E-Rows | Cost (%CPU)|


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


|   0 | SELECT STATEMENT             |      |        |     3 (100)|


|   1 |  MAT_VIEW REWRITE ACCESS FULL| MV1  |      4 |     3   (0)|


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


Note


-----


   - Warning: basic plan statistics not available. These are only collected when:


       * hint 'gather_plan_statistics' is used for the statement or


       * parameter 'statistics_level' is set to 'ALL', at session or system level




20 rows selected.


Elapsed: 00:00:00.34


SQL> select sql_id,child_number,sql_text from v$sql where sql_id='crucrsdqdrm0b';


SQL_ID        CHILD_NUMBER SQL_TEXT


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


crucrsdqdrm0b            0 select channel_id,sum(amount_sold),count(*) from sales group by channel_id


Elapsed: 00:00:00.01


--可以发现刷新后,一切OK!




				


				
时间： 2024-11-05 21:36:46

		
		


		


	

	
	

		


		
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