Oracle 11g Release 1 (11.1)——聚簇和非聚簇的简单查询比较
2012-08-25 23:14
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本文内容
创建非聚簇的相关表创建聚簇
简单查询比较
创建非聚簇的相关模式对象
创建EMPLOYEES和DEPTMENTS表。[code]--Createtable
createtableEMPLOYEES
(
EMPNONUMBER(4)notnull,
ENAMEVARCHAR2(10),
JOBVARCHAR2(9),
MGRNUMBER(4),
HIREDATEDATE,
SALNUMBER(7,2),
COMMNUMBER(7,2),
DEPTNONUMBER(3)
)
tablespaceMYTBS
pctfree10
initrans1
maxtrans255
storage
(
initial64K
next1M
minextents1
maxextentsunlimited
);
--Create/Recreateprimary,uniqueandforeignkeyconstraints
altertableEMPLOYEES
addconstraintPK_EMPLOYEES_EMPNOprimarykey(EMPNO)
usingindex
tablespaceMYTBS
pctfree10
initrans2
maxtrans255
storage
(
initial64K
next1M
minextents1
maxextentsunlimited
);
--Createtable
createtableDEPTMENTS
(
DEPTNONUMBER(3)notnull,
DNAMEVARCHAR2(14),
LOCVARCHAR2(13)
)
tablespaceMYTBS
pctfree10
initrans1
maxtrans255
storage
(
initial64K
next1M
minextents1
maxextentsunlimited
);
--Create/Recreateprimary,uniqueandforeignkeyconstraints
altertableDEPTMENTS
addconstraintPK_DEPTMENTS_DEPTNOprimarykey(DEPTNO)
usingindex
tablespaceMYTBS
pctfree10
initrans2
maxtrans255
storage
(
initial64K
next1M
minextents1
maxextentsunlimited
);
[/code]
创建聚簇的相关模式对象
创建聚簇emp_dept、聚簇的表emp和dept，以及聚簇索引emp_dept_index。[code]--CreateCluster
CREATECLUSTERemp_dept(deptnoNUMBER(3))
SIZE600
TABLESPACEmytbs
STORAGE(INITIAL200K
NEXT300K
MINEXTENTS2
PCTINCREASE33);
--Createtable
createtableEMP
(
EMPNONUMBER(4)notnull,
ENAMEVARCHAR2(10),
JOBVARCHAR2(9),
MGRNUMBER(4),
HIREDATEDATE,
SALNUMBER(7,2),
COMMNUMBER(7,2),
DEPTNONUMBER(3)
)
clusterEMP_DEPT(DEPTNO);
--Create/Recreateprimary,uniqueandforeignkeyconstraints
altertableEMP
addconstraintPK_EMP_EMPNOprimarykey(EMPNO)
usingindex
tablespaceMYTBS
pctfree10
initrans2
maxtrans255
storage
(
initial64K
next1M
minextents1
maxextentsunlimited
);
--Createtable
createtableDEPT
(
DEPTNONUMBER(3)notnull,
DNAMEVARCHAR2(14),
LOCVARCHAR2(13)
)
clusterEMP_DEPT(DEPTNO);
--Create/Recreateprimary,uniqueandforeignkeyconstraints
altertableDEPT
addconstraintPK_DEPT_DEPTNOprimarykey(DEPTNO)
usingindex
tablespaceMYTBS
pctfree10
initrans2
maxtrans255
storage
(
initial64K
next1M
minextents1
maxextentsunlimited
);
--CreateClusterindex
CREATEINDEXemp_dept_index
ONCLUSTERemp_dept
TABLESPACEMYTBS
STORAGE(INITIAL50K
NEXT50K
MINEXTENTS2
MAXEXTENTS10
PCTINCREASE33);
[/code]
向非聚簇的表和聚簇的表插入数据
下载并执行简单查询比较
示例1：比较等值连接[code] [code]SQL>;EXPLAINPLAN
2SETSTATEMENT_ID='ex_plan1'
3FOR
4SELECT*
5FROMemployeest1,deptmentst2
6WHEREt1.deptno=t2.deptno;
Explained
SQL>;SELECTplan_table_output
2FROMTABLE(DBMS_XPLAN.display(NULL,'ex_plan1','TYPICAL'));
PLAN_TABLE_OUTPUT
----------------------------------------------------------------------------------------------------
Planhashvalue:3396288718
----------------------------------------------------------------------------------------------------
|Id|Operation|Name|Rows|Bytes|Cost(%CPU)|Time|
----------------------------------------------------------------------------------------------------
|0|SELECTSTATEMENT||14|812|6(17)|00:00:01|
|1|MERGEJOIN||14|812|6(17)|00:00:01|
|2|TABLEACCESSBYINDEXROWID|DEPTMENTS|4|80|2(0)|00:00:01|
|3|INDEXFULLSCAN|PK_DEPTMENTS_DEPTNO|4||1(0)|00:00:01|
|*4|SORTJOIN||14|532|4(25)|00:00:01|
|5|TABLEACCESSFULL|EMPLOYEES|14|532|3(0)|00:00:01|
----------------------------------------------------------------------------------------------------
PredicateInformation(identifiedbyoperationid):
---------------------------------------------------
4-access("T1"."DEPTNO"="T2"."DEPTNO")filter("T1"."DEPTNO"="T2"."DEPTNO")18rowsselected
SQL>;EXPLAINPLAN
2SETSTATEMENT_ID='ex_plan2'
3FOR
4SELECT*
5FROMempt1,deptt2
6WHEREt1.deptno=t2.deptno;
Explained
SQL>;SELECTplan_table_output
2FROMTABLE(DBMS_XPLAN.display(NULL,'ex_plan2','TYPICAL'));
PLAN_TABLE_OUTPUT
----------------------------------------------------------------------------------------------------
Planhashvalue:2705476012
----------------------------------------------------------------------------------------
|Id|Operation|Name|Rows|Bytes|Cost(%CPU)|Time|
----------------------------------------------------------------------------------------
|0|SELECTSTATEMENT||14|812|6(17)|00:00:01|
|1|MERGEJOIN||14|812|6(17)|00:00:01|
|2|TABLEACCESSCLUSTER|DEPT|4|80|2(0)|00:00:01|
|3|INDEXFULLSCAN|EMP_DEPT_INDEX|1||1(0)|00:00:01|
|*4|SORTJOIN||14|532|4(25)|00:00:01|
|5|TABLEACCESSFULL|EMP|14|532|3(0)|00:00:01|
----------------------------------------------------------------------------------------
PredicateInformation(identifiedbyoperationid):
---------------------------------------------------
4-access("T1"."DEPTNO"="T2"."DEPTNO")filter("T1"."DEPTNO"="T2"."DEPTNO")18rowsselected
SQL>
[/code]
[/code]
示例2：比较左外连接
[code] [code]SQL>;EXPLAINPLAN
2SETSTATEMENT_ID='ex_plan1'
3FOR
4SELECT*
5FROMemployeest1LEFTJOINdeptmentst2ON(t1.deptno=t2.deptno);
Explained
SQL>;SELECTplan_table_output
2FROMTABLE(DBMS_XPLAN.display(NULL,'ex_plan1','TYPICAL'));
PLAN_TABLE_OUTPUT
----------------------------------------------------------------------------------------------------
Planhashvalue:47896472
--------------------------------------------------------------------------------
|Id|Operation|Name|Rows|Bytes|Cost(%CPU)|Time|
--------------------------------------------------------------------------------
|0|SELECTSTATEMENT||14|812|7(15)|00:00:01|
|*1|HASHJOINOUTER||14|812|7(15)|00:00:01|
|2|TABLEACCESSFULL|EMPLOYEES|14|532|3(0)|00:00:01|
|3|TABLEACCESSFULL|DEPTMENTS|4|80|3(0)|00:00:01|
--------------------------------------------------------------------------------
PredicateInformation(identifiedbyoperationid):
---------------------------------------------------
1-access("T1"."DEPTNO"="T2"."DEPTNO"(+))15rowsselected
SQL>;EXPLAINPLAN
2SETSTATEMENT_ID='ex_plan2'
3FOR
4SELECT*
5FROMempt1LEFTJOINdeptt2ON(t1.deptno=t2.deptno);
Explained
SQL>;SELECTplan_table_output
2FROMTABLE(DBMS_XPLAN.display(NULL,'ex_plan2','TYPICAL'));
PLAN_TABLE_OUTPUT
----------------------------------------------------------------------------------------------------
Planhashvalue:3577968021
------------------------------------------------------------------------------
|Id|Operation|Name|Rows|Bytes|Cost(%CPU)|Time|
------------------------------------------------------------------------------
|0|SELECTSTATEMENT||14|812|17(0)|00:00:01|
|1|NESTEDLOOPSOUTER||14|812|17(0)|00:00:01|
|2|TABLEACCESSFULL|EMP|14|532|3(0)|00:00:01|
|*3|TABLEACCESSCLUSTER|DEPT|1|20|1(0)|00:00:01|
------------------------------------------------------------------------------
PredicateInformation(identifiedbyoperationid):
---------------------------------------------------
3-filter("T1"."DEPTNO"="T2"."DEPTNO"(+))15rowsselected
SQL>
[/code]
[/code]
示例3：比较选择部门编号为10的所有员工
[code] [code]SQL>;EXPLAINPLAN
2SETSTATEMENT_ID='ex_plan1'
3FOR
4SELECTt1.dname,
5t1.loc,
6t2.empno,
7t2.ename,
8t2.job,
9t2.mgr,
10t2.hiredate,
11t2.sal
12FROMdeptmentst1LEFTJOINemployeest2ON(t1.deptno=t2.deptno)
13WHEREt1.deptno=10;
Explained
SQL>;SELECTplan_table_output
2FROMTABLE(DBMS_XPLAN.display(NULL,'ex_plan1','TYPICAL'));
PLAN_TABLE_OUTPUT
----------------------------------------------------------------------------------------------------
Planhashvalue:2928143533
----------------------------------------------------------------------------------------------------
|Id|Operation|Name|Rows|Bytes|Cost(%CPU)|Time|
----------------------------------------------------------------------------------------------------
|0|SELECTSTATEMENT||3|171|4(0)|00:00:01|
|1|NESTEDLOOPSOUTER||3|171|4(0)|00:00:01|
|2|TABLEACCESSBYINDEXROWID|DEPTMENTS|1|20|1(0)|00:00:01|
|*3|INDEXUNIQUESCAN|PK_DEPTMENTS_DEPTNO|1||0(0)|00:00:01|
|*4|TABLEACCESSFULL|EMPLOYEES|3|111|3(0)|00:00:01|
----------------------------------------------------------------------------------------------------
PredicateInformation(identifiedbyoperationid):
---------------------------------------------------
3-access("T1"."DEPTNO"=10)4-filter("T2"."DEPTNO"(+)=10)17rowsselected
SQL>;EXPLAINPLAN
2SETSTATEMENT_ID='ex_plan2'
3FOR
4SELECTt1.dname,
5t1.loc,
6t2.empno,
7t2.ename,
8t2.job,
9t2.mgr,
10t2.hiredate,
11t2.sal
12FROMdeptt1LEFTJOINempt2ON(t1.deptno=t2.deptno)
13WHEREt1.deptno=10;
Explained
SQL>;SELECTplan_table_output
2FROMTABLE(DBMS_XPLAN.display(NULL,'ex_plan2','TYPICAL'));
PLAN_TABLE_OUTPUT
----------------------------------------------------------------------------------------------------
Planhashvalue:4275711305
-----------------------------------------------------------------------------------------------
|Id|Operation|Name|Rows|Bytes|Cost(%CPU)|Time|
-----------------------------------------------------------------------------------------------
|0|SELECTSTATEMENT||3|171|2(0)|00:00:01|
|1|NESTEDLOOPSOUTER||3|171|2(0)|00:00:01|
|2|TABLEACCESSBYINDEXROWID|DEPT|1|20|1(0)|00:00:01|
|*3|INDEXUNIQUESCAN|PK_DEPT_DEPTNO|1||0(0)|00:00:01|
|*4|TABLEACCESSCLUSTER|EMP|3|111|1(0)|00:00:01|
-----------------------------------------------------------------------------------------------
PredicateInformation(identifiedbyoperationid):
---------------------------------------------------
3-access("T1"."DEPTNO"=10)4-filter("T2"."DEPTNO"(+)=10)17rowsselected
SQL>
[/code]
[/code]
备注：
执行计划输出中Operation列最后一行。前者的访问路径是全表扫描，而后则是聚簇。这个区别决定了之后的差异。
执行计划输出中Rows和Bytes列相同。因为两个语句的WHERE子句相同。
但是，Cost列（CPU利用率）就有差异了。
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