DB2 UDB for z/OS Version 8 Performance Topics - IBM Redbooks

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3.15.1 Installation commands. Of course, the RUNSTATS input can also be copied into a batch job and executed outside of Statistics Advisor. Installing the Java Universal Driver on DB2 V8 provides Visual Explain with the stored procedures used by Visual Explain. See APAR PQ62695. Additionally, the stored procedure SYSIBM.SQLCAMESSAGE is installed. This provides error message descriptions for SQL errors in Visual Explain. For more information, see the book DB2 for z/OS and OS/390: Ready for Java, SG24-6435. Visual Explain is available for download from the Web site: http://www.ibm.com/software/data/db2/zos/osc/ve/index.html It is also part of the DB2 Management Client Package (no charge feature of DB2) on a CD-ROM. After the install, you need to set up a JDBC connection. You can do so by using the restricted-use copy of DB2 Connect Personal Edition V8 for Windows which is provided with the Management Client Package. Instead of using the Configuration Assistant tool that comes with DB2 Connect, you can set up your connection via Visual Explain. Make sure the DB2 Connect packages have been previously bound on your target DB2 system. If you are using a TCP/IP connection to the host, you need to have the port number from your subsystem. The configuration is very simple and straightforward and all required information can be entered on a single window. Visual Explain has a Help function which describes its features. For more details on the results provided by Visual Explain, and for more information on how to use it, refer to section 10.19, Visual Explain enhancements of DB2 UDB for z/OS Version 8: Everything You Ever Wanted to Know,... and More, SG24-6079. Note: When you run Visual Explain for the first time, Visual Explain tells you if you do not have the following tables: DSN_STATEMNT_TABLE, PLAN_TABLE, DSN_DETCOST_TABLE, DSN_PREDICAT_TABLE, DSN_STRUCT_TABLE, DSN_FILTER_TABLE, DSN_SORT_TABLE, DSN_SORTKEY_TABLE, DSN_PGROUP_TABLE, DSN_PTASK_TABLE, DSN_PGRANGE_TABLE. And if you do not have them, Visual Explain creates them for you. 3.15.2 Visual Explain consistency query analysis As an example, we are going to use Visual Explain to EXPLAIN one of the queries used for catalog consistency checking. These queries are shipped in SDSNSAMP(DSNTESQ) to help you evaluate the health of your DB2 catalog. But first we describe the access plan graph. This graph can contain three types of nodes: ► Data source nodes A data source node represents a physical data store in the database, such as a table or index. ► Operator nodes An operator node indicates an operation, such as a nested loop join, that is performed on the data source, or on the result of a previous operation ► Auxiliary nodes 112 DB2 UDB for z/OS Version 8 Performance Topics
An auxiliary node includes any nodes that are neither data source nodes nor operator nodes. Both query nodes and query block nodes are classified as auxiliary nodes. Most of the nodes have corresponding descriptors, which store detailed information about the data source, query, or operation that is represented by the node. The Descriptor window lists all of the attribute values for the data source, query, or operation that is represented by the node. From the Descriptor window, you can also link to any related descriptors. For example, from the descriptor for a table node, you can link to the descriptors for the indexes that are defined on that table. We use the consistency query 31, listed in Appendix 3-11, “Old consistency query 31” on page 113 to show an example of the EXPLAIN. Table 3-11 Old consistency query 31 The old Query 31 SELECT NAME FROM SYSIBM.SYSPLAN PL WHERE PLENTRIES = 0 AND NOT EXISTS (SELECT * FROM SYSIBM.SYSDBRM WHERE PLNAME = PL.NAME); This query with correlated subquery selects the names of plans that have PLENTRIES=0 and have no DBRM pointing to the name of the plan. If you want more information about the consistency query, take a look at 9.5, “Catalog consistency query DSNTESQ” on page 359. There you find some measurements and more details about it. Now let us analyze the Visual Explain from the Query 31. Figure 3-47 shows the EXPLAIN and tells us that the cost of CPU is 2 milliseconds (in service units the cost is 32). Chapter 3. SQL performance 113
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ibm.com/redbooks Front cover DB2 UD
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Note: Before using this information
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2.5.3 Increased number of deferred
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4.5.2 Conclusion . . . . . . . . .
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7.4.1 ODBC Unicode support . . . .
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x DB2 UDB for z/OS Version 8 Perfor
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3-48 Consistency query - 31 New . .
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xiv DB2 UDB for z/OS Version 8 Perf
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8-5 CF Request Batching - DB2 CPU .
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xviii DB2 UDB for z/OS Version 8 Pe
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Trademarks The following terms are
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Added information The following APA
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► Added reference to June 15, 200
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Michael Parbs is a DB2 Specialist w
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Hugh Smith Jim Teng John Tobler Yoi
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xxx DB2 UDB for z/OS Version 8 Perf
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1.1 Overview 1.1.1 Architecture IBM
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- Column data type changes can be d
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1.1.3 Data warehouse 1.1.4 Performa
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Volatile (or cluster) tables, used
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In this chapter we anticipate the a
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2.1.3 I/O time 2.1.4 Virtual storag
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► The performance benchmarks for
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application that can have great pot
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Because you can significantly incre
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The possible increase in thread foo
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2.5.9 Unicode parser Important: Con
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You can keep the DBRMs in EBCDIC fo
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Macro Parameter Old value New value
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28 DB2 UDB for z/OS Version 8 Perfo
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► Parallel sort enhancement Paral
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Characteristics of the host variabl
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3.1.4 Performance Update 10 rows us
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► Complexity of the fetch. The fi
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► More rows per one SQL statement
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3.2.1 Creating MQTs MQTs compared t
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Special register CURRENT REFRESH AG
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the materialized query table. If it
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Figure 3-9 MQTs and short running q
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► The elapsed time is 22 times sm
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Figure 3-13 Regrouping on MQT resul
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EVE.EXT = 'ADD BILL' AND EVE.TXC =
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Star Schema Figure 3-15 Star schema
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merge joins and work file usage. DB
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Star join access path without a spa
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3.3.4 Performance Sparse index for
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Page 96 and 97: 3.3.5 Conclusion Star join workload
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Page 100 and 101: But not all mismatched numeric type
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Page 104 and 105: Query performance problem Lack of m
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Page 108 and 109: 3.5.2 Conclusions Figure 3-31 Acces
Page 110 and 111: Mismatched data types SELECT COUNT(
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Page 114 and 115: 3.7.2 Conclusions Example 3-9 Multi
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Page 118 and 119: 3.8.3 Conclusion The measurements s
Page 120 and 121: 100 Inserts activated trigger 100 t
Page 122 and 123: 3.10.2 Conclusion 100 Inserts activ
Page 124 and 125: stores the selected columns from ea
Page 126 and 127: While there is no optimistic lockin
Page 128 and 129: FETCH FROM Figure 3-45 FETCH syntax
Page 130 and 131: ► Measurement data collected with
Page 132 and 133: application has decidedly higher Cl
Page 134 and 135: Static updatable cursor You can see
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Page 138 and 139: 3.12.5 Conclusion Multi-row FETCH a
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Page 142 and 143: 3.14.2 Conclusion Percent reduction
Page 146 and 147: Figure 3-47 Explain of the old cons
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Page 156 and 157: Before the introduction of MQTs, DB
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Page 160 and 161: ► Larger VSAM CI sizes: DB2 V8 in
Page 162 and 163: 4.1.1 Performance support caused al
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Page 166 and 167: The results indicate no significant
Page 168 and 169: Important: 4.1.2 Conclusion If you
Page 170 and 171: However, the combined impact of oth
Page 172 and 173: Frees up space below the bar for ot
Page 174 and 175: from the hiperpools, they were not
Page 176 and 177: So, we advise you to not overalloca
Page 178 and 179: See 4.3, “Monitoring DBM1 storage
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Page 184 and 185: KB 600 500 400 300 200 100 0 Figure
Page 186 and 187: For the same buffer pool size and o
Page 188 and 189: 4.2.3 Conclusion Nondistributed per
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The EXTENDED REGION SIZE (MAX) is t
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RDS OP POOL (MB) N/A RID POOL (MB)
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As you can now appreciate, it is im
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Megabytes A V7 Customer DBM1 Thread
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4.5.1 Performance The most buffer p
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4.6.1 Performance maintained in a 2
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4.6.2 Conclusion We can conclude th
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service for Unicode conversions, an
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overcome this, when DB2 Connect is
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INSERT HV1 1200 HV2 1200 SELECT HV1
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AIX C-program Conversion Routines P
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4.7.1 Performance The improvements
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In October 2003, a new enhancement
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UseServerEncoding data source prope
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4.8.1 Performance 4.8.2 Conclusion
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Multilevel security with row-level
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► The security level that defines
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DB2 must call RACF for this dominan
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4.9.2 Conclusion The CPU increase c
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4.10.1 Performance VSAM does not kn
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4.10.2 Conclusion 4.10.3 Striping A
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5 4 3 2 1 0 9109TLLB 4 Parallel DB2
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--------------------------- -------
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This message is completed with the
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This enhancement is introduced by P
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This record is activated by: -START
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an online transaction with very sim
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216 DB2 UDB for z/OS Version 8 Perf
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5.1 System level point-in-time reco
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BACKUP SYSTEM During backup DB2 rec
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Figure 5-1 FRBACKUP PREPARE elapsed
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Figure 5-4 BACKUP SYSTEM FULL measu
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5.1.2 Conclusion The BACKUP SYSTEM
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Figure 5-7 shows the sliding scale
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Maybe you have implemented a space
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For dynamically prepared queries, D
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► CHAR(8) to VARCHAR(8) ► CHAR(
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Before ALTER INDEX add column, a ta
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30 25 20 15 10 Figure 5-12 FETCH CP
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Percent of index pages Avg. Index L
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300 250 200 time in seconds 150 100
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REORG REBALANCE We executed and mea
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5.4 Volatile table 5.4.1 Conclusion
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If explicit clustering for a table
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Load table of 20M rows, 10 partitio
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Times in seconds 20 18 16 14 12 10
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RUNSTATS INDEX PARTITION of a DPSI
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Note that when the qualified partit
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► “NO” - Values in such colum
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5.6.10 Support for more than 245 se
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6.1 Online CHECK INDEX Online CHECK
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SORTOUT DD UNIT=SYSDA,SPACE=(CYL,(5
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- SORT 6 indexes in parallel - CHEC
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make DB2 take the maximum paralleli
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6.3 LOAD and UNLOAD delimited input
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6.3.2 Conclusion We measured the CP
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Options for cardinality and distrib
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► Number of column groups: 1 ►
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cases is the total time of RUNSTATS
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6.4.5 Conclusion Statistics Advisor
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goals for end-user services. We sho
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alanced across all members. With th
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method. Prior to DB2 V8 those array
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when compared to DB2 V7. At the ser
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7.2.2 Performance - Distributed cli
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Recommendation If you currently do
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► The DB2 Universal JDBC type 4 D
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WebSphere z/OS - DB2 z/OS V8 - Serv
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DB2 Universal Type 4 Driver - JDBC
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Use DB2 Connect when a high amount
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JCC Type 4 Direct 4:3 Concentration
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The SYSIBM.INDOUBT table and the pa
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Batch updates A batched update is a
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Example In DB2 V8 SQL/XML publishin
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INSERT INTO PUB_TAB(DOC) SELECT XML
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7.5.3 Conclusion The new XML publis
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A second role of the managed server
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7.6.3 Performance The following inf
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Impact on coupling facility: You do
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Table 8-1 shows extracts from DB2 P
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and secondary GBP structures have t
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DB2 member already has the table sp
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8.2.1 Performance We ran a number o
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esolve any contention. This extra a
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There is also no need to use RELEAS
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Table 8-12 DB2 I/O CI Limit Removal
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8.5 Miscellaneous items In this sec
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DB2 V8 improves Restart Light. If i
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9.1 Unicode catalog DB2 for z/OS su
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that all applications are converted
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- CLASST: Specifies the threshold a
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From these measurements we observe
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Class 1 CPU time (MSEC) 200 150 100
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dynamic statement cache. If activat
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that everything is ready. This step
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Table Number of rows SYSDATABASE 75
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In Figure 9-7 we describe the perfo
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Old - Query 5 New - Query 5 CPU (se
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Query 35 36 Old DSNTESQ CPU 1 hr 1
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10.1 DB2 Estimator DB2 Estimator V8
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- REAL AND AUXILIARY STORAGE This i
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Another use is during back out of a
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In DB2, the IBM Data Encryption too
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The utilities ran on a G7 Turbo wit
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time Figure 10-1 DB2 HPU vs. UNLOAD
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DSNTIAUL with multi-row fetch The r
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A.1 Maintenance for DB2 V8 The APAR
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APAR # Area Text PTF and Notes PQ88
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APAR # Area Text PTF and Notes PK21
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B.1 DB2 PE Storage Statistics trace
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Storage heading Description 24 BIT
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C.1 DB2 SQL PA additional reports N
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|is the last matching predicate. Ap
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|ANL6052I *** NOTE: | |This index i
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PREDICATE ANALYSIS ----------------
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D.1 DB2 EXPLAIN EXPLAIN describes t
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Table D-2 PLAN_TABLE contents and b
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Column Type Content SORTC_ORDER BY
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Column Type Content OPTHINT CHAR(8)
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D.1.3 DSN_FUNCTION_TABLE You can us
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Example: D-1 Creating DSN_STATEMENT
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Column Type Content BIND_QUALIFIER
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ICF integrated catalog facility ICF
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► DB2 UDB for z/OS V8: Through th
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character set 174 CHECK DATA 262 CH
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Equi-join predicates 54, 402 Equiva
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MINSTOR 145-146 Mismatched data typ
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PQ84160 378, 387 PQ85764 387 PQ8584
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Sort tree nodes 144 SORTDATA 268 SO
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306 Universal Driver for SQLJ and J
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DB2 UDB for z/OS Version 8 Performa
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