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

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V8 Star Join Access Path Figure 3-21 Star join access path Star join access path in DB2 V8 had reduction in CPU time due to: ► Improved star join cost estimation that better estimates the filtering effect of dimensions ► Snowflake materialization occurs only if it is cost-effective ► Updated star join detection logic, optimization and run-time processes ► Use of in memory work files both in outside-in and inside-out join phases The measured CPU time for the top queries: ► Query 3001: CPU time in V7 = 119 sec. and in V8 = 2.3 (reduction of 98%) ► Query 3008: CPU time in V7 = 118 sec. and in V8 = 1 (reduction of 99%) ► Query 3004: CPU time in V7 = 118 sec. and in V8 = 11 (reduction of 90%) ► Query 3006: CPU time in V7 = 102 sec. and in V8 = 10 (reduction of 90%) In Memory Work File (IMWF) performance Measurements of the query workload submitted in single thread using various sizes of IMWF show: ► 20 MB vs. no IMWF - Many queries have performance gain ► 32 MB vs. 20 MB - Three more queries show improvement ► 64 MB vs. 32 MB - One more query shows improvement ► 128 MB vs. 64 MB - No performance gain Figure 3-22 shows the CPU time reduction with 64 MB IMWF when compared to no IMWF. The result indicates the effect of IMWF (comparison when IMWF is disabled and enabled) on all the other DB2 V8 supported features. When IMWF is disabled, the traditional sparse indexes are used, with the same access path. 62 DB2 UDB for z/OS Version 8 Performance Topics CPU Time (s) 140 120 100 80 60 40 20 0 2001 3001 3006 3008 2015 2005 2010 2018 2014 3004 QUERY NO V7 V8
CPU reduction using in memory work file CPU Time (s) 600 500 400 300 200 100 0 4232 4509 4416 4135 4457 4580 3016 4417 4485 4901 QUERY NO Figure 3-22 In memory work file - CPU reduction V8 NO IMWF V8 64 MB Performance improvements observed on queries from a workload with 64 MB of IMWF compared with no IMWF: ► Up to 40% elapsed time reduction ► Up to 31% CPU time reduction. Top queries from the workload: – Query 4580: CPU time NO IMWF = 560 sec. and with IMWF = 446 (reduction of 21%) – Query 4485: CPU time NO IMWF = 559 sec. and with IMWF = 386 (reduction of 31%) – Query 4901: CPU time NO IMWF = 553 sec. and with IMWF = 411 (reduction of 25%) In practical environments 128 MB to 256 MB can be a good starting point, depending on the workload using the snowflake data model. Bigger improvements are anticipated in environments where work file data sets are shared concurrently with other threads, such as for sorting. Performance study on warehouse workload Total elapsed time and total CPU time were measured for 79 star join queries in a highly normalized data warehouse workload in V7 and V8. Figure 3-23 shows the improvement in performance with sparse indexes, access path changes and the use of in memory work file. Chapter 3. SQL performance 63
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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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Page 72 and 73: 3.2.1 Creating MQTs MQTs compared t
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Page 78 and 79: Figure 3-9 MQTs and short running q
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Page 82 and 83: Figure 3-13 Regrouping on MQT resul
Page 84 and 85: EVE.EXT = 'ADD BILL' AND EVE.TXC =
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Page 92 and 93: 3.3.4 Performance Sparse index for
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Page 98 and 99: . SELECT * FROM PAOLO.TORDER WHERE
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 120 and 121: 100 Inserts activated trigger 100 t
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Page 126 and 127: While there is no optimistic lockin
Page 128 and 129: FETCH FROM Figure 3-45 FETCH syntax
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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
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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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