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

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In this chapter we anticipate the answers to these questions. The details are spread across the remainder of this book. More complete answers will be provided when available from the experiences of a larger population of V8 users. This chapter contains: ► Overview of major impact items ► CPU usage ► DBM1 virtual storage mapping ► Real storage ► Compatibility mode ► New-function mode ► New installation default values ► Recent z/OS releases 10 DB2 UDB for z/OS Version 8 Performance Topics
2.1 Overview of major impact items 2.1.1 DB2 catalog 2.1.2 CPU There is a tremendous amount of new function available in DB2 V8. Like any release, there are things you really like and things you like less. And the things you like come at some cost. In this chapter we present a realistic perspective of DB2 V8 for you: The good and the not so good. Certainly, adding new function implies adding instructions, and it becomes more and more difficult to contain the increase in path length. The performance department at Silicon Valley Lab, along with DB2 development, tries to minimize the overhead you can incur with each new release. This is especially true with V8 because of the large amount of additional code. It is important that you are aware of the effect DB2 V8 has on components of DB2, such as DB2 catalog, CPU growth, virtual storage, real storage, compatibility mode, and new-function mode. The more educated and informed you are before migrating to DB2 V8, the easier the planning becomes. The migration is simplified by avoiding known pitfalls. The migration goal is a smooth and successful implementation and you can concentrate on exploiting the new functions. Important: Remember that you can only migrate to DB2 V8 from DB2 V7. It is possible to migrate to DB2 V7 from DB2 V5 by a skip release migration. However, skip release migration is not generally supported, including migration to V8. We now begin to discuss the components of DB2 V8. In DB2 V8, much of the character data in the DB2 catalog changes to the Unicode encoding scheme. This does not mean you have to change all your EBCDIC or ASCII data to Unicode. The catalog conversion to Unicode allows you to support Unicode object names and literals. But it does require that you, before migrating to DB2 V8, implement z/OS Conversion Services for your environment, and this requires an IPL. Most character columns in the DB2 catalog are converted to Unicode VARCHAR(128), and there is typically a 1 to 10% increase in the space used. If you have any user-defined indexes defined on the catalog, you may want to drop them before V8. Afterwards, you can redefine these indexes and specify them as NOT PADDED. If you do not drop these indexes, the default is PADDED and these user-defined indexes grow considerably, since many columns in the index grow often from 10 to 128 bytes. For this reason, DB2 V8 allows variable length keys (VARCHAR(128)) in an index. We anticipate that there may be some growth in the size of the DB2 catalog once you migrate. However, it really depends on a number of factors. Some installations never or infrequently perform a reorganization of the DB2 catalog. For them, the difference in size after migration may be negligible. For those who REORG on a regular basis, they can see up to a 10% increase in the size of the DB2 catalog. For details regarding the effect of Unicode on the DB2 catalog and directory, refer to 9.1.2, “Unicode parsing” on page 342. In the past, as you migrated from one release of DB2 to the next, the typical increase was not more than a 5% CPU cost. In fact, staying under 5% has been the target of DB2 development. We estimate that there is four times more code in V8 than in V7, and some CPU increase is Chapter 2. Performance overview 11
Page 1: ibm.com/redbooks Front cover DB2 UD
Page 4 and 5: Note: Before using this information
Page 6 and 7: 2.5.3 Increased number of deferred
Page 8 and 9: 4.5.2 Conclusion . . . . . . . . .
Page 10 and 11: 7.4.1 ODBC Unicode support . . . .
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Page 18 and 19: 8-5 CF Request Batching - DB2 CPU .
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Page 22 and 23: Trademarks The following terms are
Page 24 and 25: Added information The following APA
Page 26 and 27: ► Added reference to June 15, 200
Page 28 and 29: Michael Parbs is a DB2 Specialist w
Page 30 and 31: Hugh Smith Jim Teng John Tobler Yoi
Page 32 and 33: xxx DB2 UDB for z/OS Version 8 Perf
Page 34 and 35: 1.1 Overview 1.1.1 Architecture IBM
Page 36 and 37: - Column data type changes can be d
Page 38 and 39: 1.1.3 Data warehouse 1.1.4 Performa
Page 40 and 41: Volatile (or cluster) tables, used
Page 44 and 45: 2.1.3 I/O time 2.1.4 Virtual storag
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Page 48 and 49: application that can have great pot
Page 50 and 51: Because you can significantly incre
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Page 54 and 55: 2.5.9 Unicode parser Important: Con
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Page 58 and 59: Macro Parameter Old value New value
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Page 62 and 63: ► Parallel sort enhancement Paral
Page 64 and 65: Characteristics of the host variabl
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Page 68 and 69: ► Complexity of the fetch. The fi
Page 70 and 71: ► More rows per one SQL statement
Page 72 and 73: 3.2.1 Creating MQTs MQTs compared t
Page 74 and 75: Special register CURRENT REFRESH AG
Page 76 and 77: the materialized query table. If it
Page 78 and 79: Figure 3-9 MQTs and short running q
Page 80 and 81: ► The elapsed time is 22 times sm
Page 82 and 83: Figure 3-13 Regrouping on MQT resul
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Page 86 and 87: Star Schema Figure 3-15 Star schema
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3.3.4 Performance Sparse index for
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V8 Star Join Access Path Figure 3-2
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3.3.5 Conclusion Star join workload
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. SELECT * FROM PAOLO.TORDER WHERE
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But not all mismatched numeric type
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V8 shows that PL is joined with CV
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Query performance problem Lack of m
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3.5.1 Performance SORTDEVT SYSDA IN
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3.5.2 Conclusions Figure 3-31 Acces
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Mismatched data types SELECT COUNT(
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3.7.1 Performance In V8 the paralle
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3.7.2 Conclusions Example 3-9 Multi
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3.8.2 Performance We show three exa
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3.8.3 Conclusion The measurements s
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100 Inserts activated trigger 100 t
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3.10.2 Conclusion 100 Inserts activ
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stores the selected columns from ea
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While there is no optimistic lockin
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FETCH FROM Figure 3-45 FETCH syntax
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► Measurement data collected with
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application has decidedly higher Cl
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Static updatable cursor You can see
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Multi-row FETCH with a static curso
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3.12.5 Conclusion Multi-row FETCH a
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While, for or SELECT ... FROM ...
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3.14.2 Conclusion Percent reduction
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3.15.1 Installation commands. Of co
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Figure 3-47 Explain of the old cons
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in ms = 1 and the CPU cost is 16 se
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Figure 3-50 Suggested RUNSTATS stat
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Looking at the explanation, we can
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The Plug-In Options screen of Stati
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Before the introduction of MQTs, DB
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126 DB2 UDB for z/OS Version 8 Perf
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► Larger VSAM CI sizes: DB2 V8 in
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4.1.1 Performance support caused al
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Regression is about 5% better than
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The results indicate no significant
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Important: 4.1.2 Conclusion If you
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However, the combined impact of oth
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Frees up space below the bar for ot
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from the hiperpools, they were not
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So, we advise you to not overalloca
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See 4.3, “Monitoring DBM1 storage
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Table 4-4 System storage configurat
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Stack 11356 21033 85% 8648 19799 12
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KB 600 500 400 300 200 100 0 Figure
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For the same buffer pool size and o
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4.2.3 Conclusion Nondistributed per
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Important: With PTFs UK04394 (DB2 V
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- DATASPACE BP CONTROL BLOCKS = 0 M
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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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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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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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DB2 UDB for z/OS Version 8 Performance Topics - IBM Redbooks

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