【发布时间】：2014-08-27 23:39:37
【问题描述】：
我正面临查询对性能的影响，
SELECT PrivilegeID,ContainerDN,RoleContainerDN,ServiceProfile,ServiceDN,
PrivilegeName,PrivilegeDescription,PrivilegeType,PrivilegeMappingType,
PrivilegeIdentificationSource,AccessType,PrivilegeMapping,
PrivilegeOwner,PrivilegeBackupOwner,PrivilegeAdminTeam,
ProvisioningNotification,DeprovisioningNotification,Status,
InActivatedByUser,InActivationDate,ISOSR,GroupProfileName
FROM ITIMUSER.TableA
WHERE (Status='A' OR Status='P') AND (GroupProfileName IS NULL OR
GroupProfileName='ALL' OR (GroupProfileName='PosAixGroupProfile' OR
GroupProfileName='PosAixRoleProfile' OR
GroupProfileName='PosAixUserAliasProfile')) AND (ServiceDN=? OR
ServiceDN='ALL')
在某些环境中，此查询大约需要 50 秒才能执行。我有这个查询的解释计划。 我调查了一下（无论我能找到什么，我都是数据库性能工程师的新手。） 我建议以下事情，
- 增加锁定列表大小
- 增加 sortheap 大小（但不确定多少，我认为应该是
- 在 servicedn 和 status 列上添加了索引。（帮助不大）
- 通过使用 'in' 删除重运算符（如 'OR'）来调整查询
有所改进，但仍然是昂贵的查询。
对于最长的问题，我深表歉意 :) 你能看看这个 exfmt 输出并建议我更多可能的调整吗？
数据库上下文：
Parallelism: None
CPU Speed: 3.542582e-07
Comm Speed: 100
Buffer Pool size: 315392
Sort Heap size: 1574
Database Heap size: 2804
Lock List size: 20000
Maximum Lock List: 60
Average Applications: 1
Locks Available: 768000
包上下文：
SQL Type: Dynamic
Optimization Level: 5
Blocking: Block All Cursors
Isolation Level: Cursor Stability
---------------- 声明 1 第 201 节 ----------------
查询号：1
查询标签：中电
语句类型：选择
可更新：否
可删除：否
查询度数：1
原文：
SELECT PrivilegeID,ContainerDN,RoleContainerDN,ServiceProfile,ServiceDN,
PrivilegeName,PrivilegeDescription,PrivilegeType,PrivilegeMappingType,
PrivilegeIdentificationSource,AccessType,PrivilegeMapping,
PrivilegeOwner,PrivilegeBackupOwner,PrivilegeAdminTeam,
ProvisioningNotification,DeprovisioningNotification,Status,
InActivatedByUser,InActivationDate,ISOSR,GroupProfileName
FROM ITIMUSER.TableA
WHERE (Status='A' OR Status='P') AND (GroupProfileName IS NULL OR
GroupProfileName='ALL' OR (GroupProfileName='PosAixGroupProfile' OR
GroupProfileName='PosAixRoleProfile' OR
GroupProfileName='PosAixUserAliasProfile')) AND (ServiceDN=? OR
ServiceDN='ALL')
优化语句：
SELECT Q6.PRIVILEGEID AS "PRIVILEGEID", Q6.CONTAINERDN AS "CONTAINERDN",
Q6.ROLECONTAINERDN AS "ROLECONTAINERDN", Q6.SERVICEPROFILE AS
"SERVICEPROFILE", Q6.SERVICEDN AS "SERVICEDN", Q6.PRIVILEGENAME AS
"PRIVILEGENAME", Q6.PRIVILEGEDESCRIPTION AS "PRIVILEGEDESCRIPTION",
Q6.PRIVILEGETYPE AS "PRIVILEGETYPE", Q6.PRIVILEGEMAPPINGTYPE AS
"PRIVILEGEMAPPINGTYPE", Q6.PRIVILEGEIDENTIFICATIONSOURCE AS
"PRIVILEGEIDENTIFICATIONSOURCE", Q6.ACCESSTYPE AS "ACCESSTYPE",
Q6.PRIVILEGEMAPPING AS "PRIVILEGEMAPPING", Q6.PRIVILEGEOWNER AS
"PRIVILEGEOWNER", Q6.PRIVILEGEBACKUPOWNER AS "PRIVILEGEBACKUPOWNER",
Q6.PRIVILEGEADMINTEAM AS "PRIVILEGEADMINTEAM",
Q6.PROVISIONINGNOTIFICATION AS "PROVISIONINGNOTIFICATION",
Q6.DEPROVISIONINGNOTIFICATION AS "DEPROVISIONINGNOTIFICATION",
Q6.STATUS AS "STATUS", Q6.INACTIVATEDBYUSER AS "INACTIVATEDBYUSER",
Q6.INACTIVATIONDATE AS "INACTIVATIONDATE", Q6.ISOSR AS "ISOSR",
Q6.GROUPPROFILENAME AS "GROUPPROFILENAME"
FROM ITIMUSER.TableA AS Q6
WHERE Q6.SERVICEDN IN (:?, 'ALL') AND Q6.STATUS IN ('A', 'P') AND
((Q6.GROUPPROFILENAME IS NULL OR (Q6.GROUPPROFILENAME = 'ALL')) OR
(((Q6.GROUPPROFILENAME = 'PosAixGroupProfile') OR
(Q6.GROUPPROFILENAME = 'PosAixRoleProfile')) OR (Q6.GROUPPROFILENAME
= 'PosAixUserAliasProfile')))
访问计划：
Total Cost: 778.169
Query Degree: 0
Rows
RETURN
( 1)
Cost
I/O
|
24535.8
^HSJOIN
( 2)
778.169
647.617
/------------+------------\
24859 2
FETCH TBSCAN
( 3) ( 9)
772.755 5.31387e-05
647.617 0
/-----+------\ |
30140.5 144068 2
RIDSCN TABLE: ITIMUSER TABFNC: SYSIBM
( 4) TableA GENROW
115.713 Q6 Q1
28.6349
/-----+------\
6.47526 30134
SORT SORT
( 5) ( 7)
7.59396 108.119
1 27.6349
| |
6.47526 30134
IXSCAN IXSCAN
( 6) ( 8)
7.59281 89.201
1 27.6349
| |
144068 144068
索引：ITIMUSER 索引：ITIMUSER SVCDN_STATUS SVCDN_STATUS Q6 Q6
扩展诊断信息：
此语句没有扩展诊断信息。
计划详情：
1) RETURN: (Return Result)
Cumulative Total Cost: 778.169
Cumulative CPU Cost: 2.19454e+08
Cumulative I/O Cost: 647.617
Cumulative Re-Total Cost: 778.169
Cumulative Re-CPU Cost: 2.19454e+08
Cumulative Re-I/O Cost: 647.617
Cumulative First Row Cost: 778.169
Estimated Bufferpool Buffers: 649.382
Arguments:
---------
BLDLEVEL: (Build level)
DB2 v9.5.0.3 : s090225
HEAPUSE : (Maximum Statement Heap Usage)
160 Pages
STMTHEAP: (Statement heap size)
6402
Input Streams:
-------------
12) From Operator #2
Estimated number of rows: 24535.8
Number of columns: 22
Subquery predicate ID: Not Applicable
Column Names:
------------
+Q7.GROUPPROFILENAME+Q7.ISOSR
+Q7.INACTIVATIONDATE+Q7.INACTIVATEDBYUSER
+Q7.STATUS+Q7.DEPROVISIONINGNOTIFICATION
+Q7.PROVISIONINGNOTIFICATION
+Q7.PRIVILEGEADMINTEAM+Q7.PRIVILEGEBACKUPOWNER
+Q7.PRIVILEGEOWNER+Q7.PRIVILEGEMAPPING
+Q7.ACCESSTYPE
+Q7.PRIVILEGEIDENTIFICATIONSOURCE
+Q7.PRIVILEGEMAPPINGTYPE+Q7.PRIVILEGETYPE
+Q7.PRIVILEGEDESCRIPTION+Q7.PRIVILEGENAME
+Q7.SERVICEDN+Q7.SERVICEPROFILE
+Q7.ROLECONTAINERDN+Q7.CONTAINERDN
+Q7.PRIVILEGEID
2) HSJOIN: (Hash Join)
Cumulative Total Cost: 778.169
Cumulative CPU Cost: 2.19454e+08
Cumulative I/O Cost: 647.617
Cumulative Re-Total Cost: 778.169
Cumulative Re-CPU Cost: 2.19454e+08
Cumulative Re-I/O Cost: 647.617
Cumulative First Row Cost: 778.169
Estimated Bufferpool Buffers: 649.382
Arguments:
---------
BITFLTR : (Hash Join Bit Filter used)
FALSE
EARLYOUT: (Early Out flag)
LEFT
HASHCODE: (Hash Code Size)
24 BIT
TEMPSIZE: (Temporary Table Page Size)
32768
Predicates:
----------
2) Predicate used in Join
Comparison Operator: Equal (=)
Subquery Input Required: No
Filter Factor: 0.4935
Predicate Text:
--------------
(Q6.STATUS = Q2.$C0)
Input Streams:
-------------
9) From Operator #3
Estimated number of rows: 24859
Number of columns: 22
Subquery predicate ID: Not Applicable
Column Names:
------------
+Q6.ISOSR+Q6.INACTIVATIONDATE
+Q6.INACTIVATEDBYUSER
+Q6.DEPROVISIONINGNOTIFICATION
+Q6.PROVISIONINGNOTIFICATION
+Q6.PRIVILEGEADMINTEAM+Q6.PRIVILEGEBACKUPOWNER
+Q6.PRIVILEGEOWNER+Q6.PRIVILEGEMAPPING
+Q6.ACCESSTYPE
+Q6.PRIVILEGEIDENTIFICATIONSOURCE
+Q6.PRIVILEGEMAPPINGTYPE+Q6.PRIVILEGETYPE
+Q6.PRIVILEGEDESCRIPTION+Q6.PRIVILEGENAME
+Q6.SERVICEPROFILE+Q6.ROLECONTAINERDN
+Q6.CONTAINERDN+Q6.PRIVILEGEID+Q6.SERVICEDN
+Q6.GROUPPROFILENAME+Q6.STATUS
11) From Operator #9
Estimated number of rows: 2
Number of columns: 1
Subquery predicate ID: Not Applicable
Column Names:
------------
+Q2.$C0
Output Streams:
--------------
12) To Operator #1
Estimated number of rows: 24535.8
Number of columns: 22
Subquery predicate ID: Not Applicable
Column Names:
------------
+Q7.GROUPPROFILENAME+Q7.ISOSR
+Q7.INACTIVATIONDATE+Q7.INACTIVATEDBYUSER
+Q7.STATUS+Q7.DEPROVISIONINGNOTIFICATION
+Q7.PROVISIONINGNOTIFICATION
+Q7.PRIVILEGEADMINTEAM+Q7.PRIVILEGEBACKUPOWNER
+Q7.PRIVILEGEOWNER+Q7.PRIVILEGEMAPPING
+Q7.ACCESSTYPE
+Q7.PRIVILEGEIDENTIFICATIONSOURCE
+Q7.PRIVILEGEMAPPINGTYPE+Q7.PRIVILEGETYPE
+Q7.PRIVILEGEDESCRIPTION+Q7.PRIVILEGENAME
+Q7.SERVICEDN+Q7.SERVICEPROFILE
+Q7.ROLECONTAINERDN+Q7.CONTAINERDN
+Q7.PRIVILEGEID
3) FETCH : (Fetch)
Cumulative Total Cost: 772.755
Cumulative CPU Cost: 2.0417e+08
Cumulative I/O Cost: 647.617
Cumulative Re-Total Cost: 54.5714
Cumulative Re-CPU Cost: 1.54044e+08
Cumulative Re-I/O Cost: 0
Cumulative First Row Cost: 123.283
Estimated Bufferpool Buffers: 649.382
Arguments:
---------
JN INPUT: (Join input leg)
OUTER
MAX RIDS: (Maximum RIDs per list prefetch request)
1024
PREFETCH: (Type of Prefetch)
LIST
ROWLOCK : (Row Lock intent)
NEXT KEY SHARE
TABLOCK : (Table Lock intent)
INTENT SHARE
TBISOLVL: (Table access Isolation Level)
CURSOR STABILITY
Predicates:
----------
4) Sargable Predicate
Comparison Operator: In List (IN), evaluated by binary search (list sorted at run-time)
Subquery Input Required: No
Filter Factor: 0.20921
Predicate Text:
--------------
Q6.SERVICEDN IN (:?, 'ALL')
9) Sargable Predicate
Comparison Operator: Not Applicable
Subquery Input Required: No
Filter Factor: 0.824771
Predicate Text:
--------------
((Q6.GROUPPROFILENAME IS NULL OR (Q6.GROUPPROFILENAME
= 'ALL')) OR (((Q6.GROUPPROFILENAME =
'PosAixGroupProfile') OR (Q6.GROUPPROFILENAME
= 'PosAixRoleProfile')) OR
(Q6.GROUPPROFILENAME =
'PosAixUserAliasProfile')))
Input Streams:
-------------
7) From Operator #4
Estimated number of rows: 30140.5
Number of columns: 1
Subquery predicate ID: Not Applicable
Column Names:
------------
+Q6.$RID$(A)
8) From Object ITIMUSER.TableA
Estimated number of rows: 144068
Number of columns: 22
Subquery predicate ID: Not Applicable
Column Names:
------------
+Q6.ISOSR+Q6.INACTIVATIONDATE
+Q6.INACTIVATEDBYUSER
+Q6.DEPROVISIONINGNOTIFICATION
+Q6.PROVISIONINGNOTIFICATION
+Q6.PRIVILEGEADMINTEAM+Q6.PRIVILEGEBACKUPOWNER
+Q6.PRIVILEGEOWNER+Q6.PRIVILEGEMAPPING
+Q6.ACCESSTYPE
+Q6.PRIVILEGEIDENTIFICATIONSOURCE
+Q6.PRIVILEGEMAPPINGTYPE+Q6.PRIVILEGETYPE
+Q6.PRIVILEGEDESCRIPTION+Q6.PRIVILEGENAME
+Q6.SERVICEPROFILE+Q6.ROLECONTAINERDN
+Q6.CONTAINERDN+Q6.PRIVILEGEID+Q6.SERVICEDN
+Q6.GROUPPROFILENAME+Q6.STATUS
Output Streams:
--------------
9) To Operator #2
Estimated number of rows: 24859
Number of columns: 22
Subquery predicate ID: Not Applicable
Column Names:
------------
+Q6.ISOSR+Q6.INACTIVATIONDATE
+Q6.INACTIVATEDBYUSER
+Q6.DEPROVISIONINGNOTIFICATION
+Q6.PROVISIONINGNOTIFICATION
+Q6.PRIVILEGEADMINTEAM+Q6.PRIVILEGEBACKUPOWNER
+Q6.PRIVILEGEOWNER+Q6.PRIVILEGEMAPPING
+Q6.ACCESSTYPE
+Q6.PRIVILEGEIDENTIFICATIONSOURCE
+Q6.PRIVILEGEMAPPINGTYPE+Q6.PRIVILEGETYPE
+Q6.PRIVILEGEDESCRIPTION+Q6.PRIVILEGENAME
+Q6.SERVICEPROFILE+Q6.ROLECONTAINERDN
+Q6.CONTAINERDN+Q6.PRIVILEGEID+Q6.SERVICEDN
+Q6.GROUPPROFILENAME+Q6.STATUS
4) RIDSCN: (Row Identifier Scan)
Cumulative Total Cost: 115.713
Cumulative CPU Cost: 1.05646e+08
Cumulative I/O Cost: 28.6349
Cumulative Re-Total Cost: 21.0693
Cumulative Re-CPU Cost: 5.94745e+07
Cumulative Re-I/O Cost: 0
Cumulative First Row Cost: 115.712
Estimated Bufferpool Buffers: 30.4006
Arguments:
---------
NUMROWS : (Estimated number of rows)
30141
Input Streams:
-------------
3) From Operator #5
Estimated number of rows: 6.47526
Number of columns: 1
Subquery predicate ID: Not Applicable
Column Names:
------------
+Q6.$RID$(A)
6) From Operator #7
Estimated number of rows: 30134
Number of columns: 1
Subquery predicate ID: Not Applicable
Column Names:
------------
+Q6.$RID$(A)
Output Streams:
--------------
7) To Operator #3
Estimated number of rows: 30140.5
Number of columns: 1
Subquery predicate ID: Not Applicable
Column Names:
------------
+Q6.$RID$(A)
5) SORT : (Sort)
Cumulative Total Cost: 7.59396
Cumulative CPU Cost: 95860.9
Cumulative I/O Cost: 1
Cumulative Re-Total Cost: 0.0156471
Cumulative Re-CPU Cost: 44168.7
Cumulative Re-I/O Cost: 0
Cumulative First Row Cost: 7.59396
Estimated Bufferpool Buffers: 2
Arguments:
---------
DUPLWARN: (Duplicates Warning flag)
TRUE
NUMROWS : (Estimated number of rows)
7
ROWWIDTH: (Estimated width of rows)
20
SORTKEY : (Sort Key column)
1: Q6.$RID$(A)
TEMPSIZE: (Temporary Table Page Size)
32768
UNIQUE : (Uniqueness required flag)
TRUE
Input Streams:
-------------
2) From Operator #6
Estimated number of rows: 6.47526
Number of columns: 2
Subquery predicate ID: Not Applicable
Column Names:
------------
+Q6.SERVICEDN(A)+Q6.STATUS(A)
Output Streams:
--------------
3) To Operator #4
Estimated number of rows: 6.47526
Number of columns: 1
Subquery predicate ID: Not Applicable
Column Names:
------------
+Q6.$RID$(A)
6) IXSCAN: (Index Scan)
Cumulative Total Cost: 7.59281
Cumulative CPU Cost: 92629.7
Cumulative I/O Cost: 1
Cumulative Re-Total Cost: 0.0156471
Cumulative Re-CPU Cost: 44168.7
Cumulative Re-I/O Cost: 0
Cumulative First Row Cost: 7.58887
Estimated Bufferpool Buffers: 2
Arguments:
---------
MAXPAGES: (Maximum pages for prefetch)
1
PREFETCH: (Type of Prefetch)
NONE
ROWLOCK : (Row Lock intent)
NONE
SCANDIR : (Scan Direction)
FORWARD
TABLOCK : (Table Lock intent)
INTENT NONE
TBISOLVL: (Table access Isolation Level)
CURSOR STABILITY
Predicates:
----------
7) Start Key Predicate
Comparison Operator: Equal (=)
Subquery Input Required: No
Filter Factor: 4.49458e-05
Predicate Text:
--------------
(Q6.SERVICEDN = :?)
7) Stop Key Predicate
Comparison Operator: Equal (=)
Subquery Input Required: No
Filter Factor: 4.49458e-05
Predicate Text:
--------------
(Q6.SERVICEDN = :?)
Input Streams:
-------------
1) From Object ITIMUSER.SVCDN_STATUS
Estimated number of rows: 144068
Number of columns: 3
Subquery predicate ID: Not Applicable
Column Names:
------------
+Q6.SERVICEDN(A)+Q6.STATUS(A)+Q6.$RID$
Output Streams:
--------------
2) To Operator #5
Estimated number of rows: 6.47526
Number of columns: 2
Subquery predicate ID: Not Applicable
Column Names:
------------
+Q6.SERVICEDN(A)+Q6.STATUS(A)
7) SORT : (Sort)
Cumulative Total Cost: 108.119
Cumulative CPU Cost: 1.05551e+08
Cumulative I/O Cost: 27.6349
Cumulative Re-Total Cost: 18.3837
Cumulative Re-CPU Cost: 5.18936e+07
Cumulative Re-I/O Cost: 0
Cumulative First Row Cost: 108.119
Estimated Bufferpool Buffers: 28.4006
Arguments:
---------
DUPLWARN: (Duplicates Warning flag)
TRUE
NUMROWS : (Estimated number of rows)
30134
ROWWIDTH: (Estimated width of rows)
20
SORTKEY : (Sort Key column)
1: Q6.$RID$(A)
TEMPSIZE: (Temporary Table Page Size)
32768
UNIQUE : (Uniqueness required flag)
TRUE
Input Streams:
-------------
5) From Operator #8
Estimated number of rows: 30134
Number of columns: 2
Subquery predicate ID: Not Applicable
Column Names:
------------
+Q6.SERVICEDN(A)+Q6.STATUS(A)
Output Streams:
--------------
6) To Operator #4
Estimated number of rows: 30134
Number of columns: 1
Subquery predicate ID: Not Applicable
Column Names:
------------
+Q6.$RID$(A)
8) IXSCAN: (Index Scan)
Cumulative Total Cost: 89.201
Cumulative CPU Cost: 5.21489e+07
Cumulative I/O Cost: 27.6349
Cumulative Re-Total Cost: 18.3837
Cumulative Re-CPU Cost: 5.18936e+07
Cumulative Re-I/O Cost: 0
Cumulative First Row Cost: 7.58887
Estimated Bufferpool Buffers: 28.4006
Arguments:
---------
MAXPAGES: (Maximum pages for prefetch)
27
PREFETCH: (Type of Prefetch)
SEQUENTIAL
ROWLOCK : (Row Lock intent)
NONE
SCANDIR : (Scan Direction)
FORWARD
TABLOCK : (Table Lock intent)
INTENT NONE
TBISOLVL: (Table access Isolation Level)
CURSOR STABILITY
Predicates:
----------
8) Start Key Predicate
Comparison Operator: Equal (=)
Subquery Input Required: No
Filter Factor: 0.209165
Predicate Text:
--------------
(Q6.SERVICEDN = 'ALL')
8) Stop Key Predicate
Comparison Operator: Equal (=)
Subquery Input Required: No
Filter Factor: 0.209165
Predicate Text:
--------------
(Q6.SERVICEDN = 'ALL')
Input Streams:
-------------
4) From Object ITIMUSER.SVCDN_STATUS
Estimated number of rows: 144068
Number of columns: 3
Subquery predicate ID: Not Applicable
Column Names:
------------
+Q6.SERVICEDN(A)+Q6.STATUS(A)+Q6.$RID$
Output Streams:
--------------
5) To Operator #7
Estimated number of rows: 30134
Number of columns: 2
Subquery predicate ID: Not Applicable
Column Names:
------------
+Q6.SERVICEDN(A)+Q6.STATUS(A)
9) TBSCAN: (Table Scan)
Cumulative Total Cost: 5.31387e-05
Cumulative CPU Cost: 150
Cumulative I/O Cost: 0
Cumulative Re-Total Cost: 5.31387e-05
Cumulative Re-CPU Cost: 150
Cumulative Re-I/O Cost: 0
Cumulative First Row Cost: 3.18832e-05
Estimated Bufferpool Buffers: 0
Arguments:
---------
GENRVALS: (GENROW IN List values)
VALUES ('A', 'P')
JN INPUT: (Join input leg)
INNER
MAXPAGES: (Maximum pages for prefetch)
ALL
PREFETCH: (Type of Prefetch)
NONE
ROWLOCK : (Row Lock intent)
NEXT KEY SHARE
SCANDIR : (Scan Direction)
FORWARD
TABLOCK : (Table Lock intent)
INTENT SHARE
TBISOLVL: (Table access Isolation Level)
CURSOR STABILITY
Input Streams:
-------------
10) From Object SYSIBM.GENROW
Estimated number of rows: 2
Number of columns: 1
Subquery predicate ID: Not Applicable
Column Names:
------------
+Q1.NUMB
Output Streams:
--------------
11) To Operator #2
Estimated number of rows: 2
Number of columns: 1
Subquery predicate ID: Not Applicable
Column Names:
------------
+Q2.$C0
访问计划中使用的对象：
Schema: ITIMUSER
Name: SVCDN_STATUS
Type: Index
Time of creation: 2014-07-04-07.27.27.866382
Last statistics update: 2014-07-04-09.37.29.120054
Number of columns: 2
Number of rows: 144068
Width of rows: -1
Number of buffer pool pages: 2409
Distinct row values: No
Tablespace name: ENROLE_DATA
Tablespace overhead: 7.500000
Tablespace transfer rate: 0.060000
Source for statistics: Single Node
Prefetch page count: 32
Container extent page count: 32
Index clustering statistic: 94.000000
Index leaf pages: 131
Index tree levels: 2
Index full key cardinality: 26559
Index first key cardinality: 22249
Index first 2 keys cardinality: 26559
Index first 3 keys cardinality: -1
Index first 4 keys cardinality: -1
Index sequential pages: 130
Index page density: 99
Index avg sequential pages: 130
Index avg gap between sequences:0
Index avg random pages: 0
Fetch avg sequential pages: -1
Fetch avg gap between sequences:-1
Fetch avg random pages: -1
Index RID count: 144068
Index deleted RID count: 0
Index empty leaf pages: 0
Base Table Schema: ITIMUSER
Base Table Name: TableA
Columns in index:
SERVICEDN(A)
STATUS(A)
Schema: ITIMUSER
Name: TableA
Type: Table
Time of creation: 2012-02-24-15.04.35.829088
Last statistics update: 2014-07-04-09.37.29.120054
Number of columns: 23
Number of rows: 144068
Width of rows: 542
Number of buffer pool pages: 2409
Number of data partitions: 1
Distinct row values: No
Tablespace name: ENROLE_DATA
Tablespace overhead: 7.500000
Tablespace transfer rate: 0.060000
Source for statistics: Single Node
Prefetch page count: 32
Container extent page count: 32
Table overflow record count: 0
Table Active Blocks: -1
Average Row Compression Ratio: 0
Percentage Rows Compressed: 0
Average Compressed Row Size: 0
Schema: SYSIBM
Name: GENROW
Type: Table Function
Time of creation:
Last statistics update:
Number of columns: 1
Number of rows: 2
Width of rows: 11
Number of buffer pool pages: -1
Distinct row values: No
Source for statistics: Single Node
注意： AIX 上的 DB2 LUW 9.5。
【问题讨论】：
-
我会尝试在
ITIMUSER (SERVICEDN, GROUPPROFILENAME, STATUS)上建立索引。但是，涉及GROUPPROFILENAME的谓词估计过滤因子为 0.8，这基本上意味着您将有 80% 的表匹配，因此您最终仍会读取很多行。结果集的估计大小（24.5K 行）是否接近现实？ -
排序堆大约有 1500 页，非常小。您是否在此语句中看到排序溢出？如果是这样，请尝试将排序堆加倍，直到您摆脱它们。
-
IN(...)操作员倾向于生成与一系列ORs 相同的计划步骤（因为它们通常是等效的）。您可能可以使用某种虚拟表（即 CTE 或其他VALUES(...)表引用），以便您可以JOIN对其进行操作，但null条件会抛出一些问题（我我不确定如果您选择 80% 的行会有多大帮助）。 -
@mustaccio ：是的，我仍在检查查询是否需要那么多行。这是别人写的逻辑。无论如何，感谢您的帮助，如果您发现任何问题，请提出建议。
-
问题不在于你是否需要那么多行；问题是返回的实际行数是否接近优化器认为的（24.5K）。
标签： database performance db2 database-performance db2-luw