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db2像oracle一样使用hints（guidelines）
C:\DB2>more f3.sql
SELECT d.DEPTNAME,e.FIRSTNME,e.LASTNAME
FROM DEPARTMENT D,EMPLOYEE E
WHERE d.DEPTNO = e.WORKDEPT AND e.EMPNO LIKE ‘0001%‘ /*<OPTGUIDELINES>
<MSJOIN>
<TBSCAN TABLE=‘D‘/> <TBSCAN TABLE=‘E‘/>
</MSJOIN>
</OPTGUIDELINES>*/;
C:\DB2>
C:\DB2>db2expln -d sample -f f3.sql -g -t -z ";"
DB2 Universal Database Version 10.5, 5622-044 (c) Copyright IBM Corp. 1991, 2012
Licensed Material - Program Property of IBM
IBM DB2 Universal Database SQL and XQUERY Explain Tool
DB2 Universal Database Version 10.5, 5622-044 (c) Copyright IBM Corp. 1991, 2012
Licensed Material - Program Property of IBM
IBM DB2 Universal Database SQL and XQUERY Explain Tool
******************** DYNAMIC ***************************************
==================== STATEMENT ==========================================
Isolation Level = Cursor Stability
Blocking = Block Unambiguous Cursors
Query Optimization Class = 5
Partition Parallel = No
Intra-Partition Parallel = No
SQL Path = "SYSIBM", "SYSFUN", "SYSPROC", "SYSIBMADM",
"LIAO"
Statement:
SELECT d.DEPTNAME, e.FIRSTNME, e.LASTNAME
FROM DEPARTMENT D, EMPLOYEE E
WHERE d.DEPTNO =e.WORKDEPT AND e.EMPNO LIKE ‘0001%‘
/*<OPTGUIDELINES> <MSJOIN> <TBSCAN TABLE=‘D‘ /> <TBSCAN
TABLE=‘E‘ /> </MSJOIN> </OPTGUIDELINES>*/
Section Code Page = 1208
Estimated Cost = 13.634712
Estimated Cardinality = 9.816054
Access Table Name = LIAO.EMPLOYEE ID = 2,6
| Index Scan: Name = LIAO.PK_EMPLOYEE ID = 1
| | Regular Index (Not Clustered)
| | Index Columns:
| | | 1: EMPNO (Ascending)
| #Columns = 4
| Skip Inserted Rows
| Avoid Locking Committed Data
| Currently Committed for Cursor Stability
| Evaluate Predicates Before Locking for Key
| #Key Columns = 1
| | Start Key: Inclusive Value
| | | 1: ‘0001‘
| | Stop Key: Inclusive Value
| | | 1: ‘0001 ‘
| Data Prefetch: Sequential(0), Readahead
| Index Prefetch: None
| Lock Intents
| | Table: Intent Share
| | Row : Next Key Share
| Sargable Predicate(s)
| | Process Build Table for Hash Join
Hash Join
| Early Out: Single Match Per Inner Row
| Estimated Build Size: 4000
| Estimated Probe Size: 4000
| Access Table Name = LIAO.DEPARTMENT ID = 2,5
| | #Columns = 2
| | Skip Inserted Rows
| | Avoid Locking Committed Data
| | Currently Committed for Cusor Stability
| | May participate in Scan Sharing structures
| | Scan may start anywhere and wrap, for completion
| | Fast scan, for purposes of scan sharing management
| | Scan can be throttled in scan sharing management
| | Relation Scan
| | | Prefetch: Eligible
| | Lock Intents
| | | Table: Intent Share
| | | Row : Next Key Share
| | Sargable Predicate(s)
| | | Process Probe Table for Hash Join
Return Data to Application
| #Columns = 3
End of section
Optimizer Plan:
Rows
Operator
(ID)
Cost
9.81605
RETURN
( 1)
13.6347
|
9.81605
HSJOIN
( 2)
13.6347
/ \
14 9.81605
TBSCAN FETCH
( 3) ( 4)
6.81583 6.8181
| / \
14 9.81605 42
Table: IXSCAN Table:
LIAO ( 5) LIAO
DEPARTMENT 0.00986447 EMPLOYEE
|
42
Index:
LIAO
PK_EMPLOYEE
C:\DB2>db2set DB2_OPTPROFILE=YES
C:\DB2>db2set -all
[e] DB2PATH=C:\v105\IBM\SQLLIB
[i] DB2_OPTPROFILE=YES
[i] DB2INSTOWNER=LIAO-PC
[i] DB2PORTRANGE=60000:60005
[i] DB2INSTPROF=C:\V105\PROGRAMDATA\\IBM\DB2\DB2COPY1
[i] DB2COMM=TCPIP
[g] DB2_EXTSECURITY=NO
[g] DB2_COMMON_APP_DATA_PATH=C:\v105\ProgramData\
[g] DB2SYSTEM=LIAO-PC
[g] DB2PATH=C:\v105\IBM\SQLLIB
[g] DB2INSTDEF=DB2
[g] DB2ADMINSERVER=DB2DAS00
C:\DB2>db2stop
2015-12-04 00:43:34 0 0 SQL1025N 未停止数据库，因为数据库仍是活动的。
SQL1025N 未停止数据库，因为数据库仍是活动的。
C:\DB2>db2stop force
2015-12-04 00:43:40 0 0 SQL1064N DB2STOP 处理成功。
SQL1064N DB2STOP 处理成功。
C:\DB2>db2start
2015-12-04 00:43:48 0 0 SQL1063N DB2START 处理成功。
SQL1063N DB2START 处理成功。
C:\DB2>db2expln -d sample -f f3.sql -g -t -z ";"
DB2 Universal Database Version 10.5, 5622-044 (c) Copyright IBM Corp. 1991, 2012
Licensed Material - Program Property of IBM
IBM DB2 Universal Database SQL and XQUERY Explain Tool
DB2 Universal Database Version 10.5, 5622-044 (c) Copyright IBM Corp. 1991, 2012
Licensed Material - Program Property of IBM
IBM DB2 Universal Database SQL and XQUERY Explain Tool
******************** DYNAMIC ***************************************
==================== STATEMENT ==========================================
Isolation Level = Cursor Stability
Blocking = Block Unambiguous Cursors
Query Optimization Class = 5
Partition Parallel = No
Intra-Partition Parallel = No
SQL Path = "SYSIBM", "SYSFUN", "SYSPROC", "SYSIBMADM",
"LIAO"
Statement:
SELECT d.DEPTNAME, e.FIRSTNME, e.LASTNAME
FROM DEPARTMENT D, EMPLOYEE E
WHERE d.DEPTNO =e.WORKDEPT AND e.EMPNO LIKE ‘0001%‘
/*<OPTGUIDELINES> <MSJOIN> <TBSCAN TABLE=‘D‘ /> <TBSCAN
TABLE=‘E‘ /> </MSJOIN> </OPTGUIDELINES>*/
Section Code Page = 1208
Estimated Cost = 13.648438
Estimated Cardinality = 9.816054
Access Table Name = LIAO.DEPARTMENT ID = 2,5
| #Columns = 2
| Skip Inserted Rows
| Avoid Locking Committed Data
| Currently Committed for Cursor Stability
| May participate in Scan Sharing structures
| Scan may start anywhere and wrap, for completion
| Fast scan, for purposes of scan sharing management
| Scan can be throttled in scan sharing management
| Relation Scan
| | Prefetch: Eligible
| Lock Intents
| | Table: Intent Share
| | Row : Next Key Share
| Sargable Predicate(s)
| | Insert Into Sorted Temp Table ID = t1
| | | #Columns = 2
| | | #Sort Key Columns = 1
| | | | Key 1: DEPTNO (Ascending)
| | | Sortheap Allocation Parameters:
| | | | #Rows = 14.000000
| | | | Row Width = 28
| | | Piped
Sorted Temp Table Completion ID = t1
Access Temp Table ID = t1
| #Columns = 2
| Relation Scan
| | Prefetch: Eligible
Merge Join
| Access Table Name = LIAO.EMPLOYEE ID = 2,6
| | #Columns = 4
| | Skip Inserted Rows
| | Avoid Locking Committed Data
| | Currently Committed for Cursor Stability
| | May participate in Scan Sharing structures
| | Scan may start anywhere and wrap, for completion
| | Fast scan, for purposes of scan sharing management
| | Scan can be throttled in scan sharing management
| | Relation Scan
| | | Prefetch: Eligible
| | Lock Intents
| | | Table: Intent Share
| | | Row : Next Key Share
| | Sargable Predicate(s)
| | | #Predicates = 1
| | | Insert Into Sorted Temp Table ID = t2
| | | | #Columns = 3
| | | | #Sort Key Columns = 1
| | | | | Key 1: WORKDEPT (Ascending)
| | | | Sortheap Allocation Parameters:
| | | | | #Rows = 10.000000
| | | | | Row Width = 32
| | | | Piped
| Sorted Temp Table Completion ID = t2
| Access Temp Table ID = t2
| | #Columns = 3
| | Relation Scan
| | | Prefetch: Eligible
Return Data to Application
| #Columns = 3
End of section
Optimizer Plan:
Rows
Operator
(ID)
Cost
9.81605
RETURN
( 1)
13.6484
|
9.81605
MSJOIN
( 2)
13.6484
/ \-\
14 *
TBSCAN |
( 3) 9.81605
6.81692 TBSCAN
| ( 7)
14 6.83002
SORT |
( 4) 9.81605
6.81674 SORT
| ( 8)
14 6.82983
TBSCAN |
( 5) 9.81605
6.81583 TBSCAN
| ( 9)
14 6.82912
Table: |
LIAO 42
DEPARTMENT Table:
LIAO
EMPLOYEE
C:\DB2>
REF:
1.Oracle hint在DB2中的实现-访问计划定制
db2像oracle一样使用hints（guidelines）
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原文地址：http://blog.csdn.net/t0nsha/article/details/50155109
