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

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4.1.1 Performance support caused almost as much CPU degradation as the 64-bit conversion, and support for variable length indexes was not far behind. Hopefully you can now appreciate how the new 64-bit architecture, combined with all the enhancements in DB2 V8, have added much more code than V7 and have also presented some significant performance challenges which have had to be overcome in order to minimize the CPU regression of V8 compared with V7. We reviewed the performance of DB2 V8, compared with DB2 V7, for a variety of different workloads, to understand the impact V8 may have on CPU for your workload. The performance measurements we compared for each workload were the ITR (Internal Throughput Rate, inversely proportional to CPU seconds used) and CPU. We begin our discussion by having a look at OLTP workloads. The variety of OLTP workloads we studied include the IRWW (IBM Relational Warehouse Workload, described in DB2 for MVS/ESA Version 4 Data Sharing Performance Topics, SG24-4611), both in a data sharing and non-data sharing environment, a number of DRDA client/server transaction workloads, a number of SAP workloads and a CICS/DB2 transaction workload. Each workload studied had a different SQL structure and therefore revealed different performance strengths and weaknesses. For example, some workloads executed reasonably simple SQL while other workloads executed more complex SQL. A number of query-based workloads have been studied to compare query performance. Over 200 queries gathered from a number of customer sites have been used. Some of these queries achieved up to 20% reduction in CPU, due primarily to improved access path enhancements. For example, a data warehouse application achieved over 30% improvement in CPU, primarily due to star join enhancements. A number of batch workloads were also studied, including a sampling of commonly used utilities. Figure 4-1 summarizes some general measurements of V8 CPU consumption compared with V7 for various workloads. These comparisons are made with no application changes to exploit any V8 new function, nor any aggressive configuration changes. This chart has been compiled from a number of different laboratory tests running various DB2 workloads. A ‘+’ means a CPU increase and a ‘-’ means a CPU decrease in V8 compared with V7. Be reminded that these trends can only be used as a guide. As always, “your mileage may vary”, since all DB2 installations and workloads are different. 130 DB2 UDB for z/OS Version 8 Performance Topics
oltp oltp in data sharing batch insert batch select batch fetch/update batch data sharing batch drda utility query Figure 4-1 CPU workload summary CPU range by workload -20% -10% 0% +10% +20% The typical customer CPU regression of DB2 V8 is anticipated to be 0 to 10% more than V7 on average. This CPU degradation is the result of the new functionality that is provided in DB2 V8, together with the overhead that comes with 64-bit addressing. Looking at it a little closer, the CPU delta is: ► 0 to +15% regression for online transaction workloads Remember, we have much more code and function in V8 compared with V7, as well as dealing with the added complication of 64-bit addressing in the DBM1 address space. ► -5 to +10% regression for online transaction workloads in data sharing environments The reason why we are able to achieve less CPU degradation in data sharing is because there are a number of performance enhancements in V8 that apply specifically to data sharing environments. For example, Lock Protocol Level 2 to reduce global lock contention. See Chapter 8, “Data sharing enhancements” on page 319 for more details. ► -5 to +20% regression in batch workloads – -5 to +5% with a heavy INSERT workload This does not represent a significant change and is comparable to DB2 V7. – -5 to +20% with a heavy SELECT workload We are able to achieve some CPU reduction for SELECT workloads because the SELECT workloads benefit from the new lock avoidance techniques used in V8. See 4.13.4, “Lock avoidance enhancements” on page 214 for more details. Applications using CURRENTDATA(YES) receive the most benefit as these do not exploit lock avoidance in DB2 V7. We see more CPU degradation (up to a 20%) as the number of columns increases. – +5% to +20% with a heavy FETCH and UPDATE workload This increase in CPU varies greatly based on the number of columns being processed. The more columns, the more CPU used. In fact, you may see as much as 20% more CPU consumed in V8 when you are processing over 100 columns in the SQL. ► -10% to +15% regression in batch workloads in a data sharing environment Chapter 4. DB2 subsystem performance 131
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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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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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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
Page 136 and 137: Multi-row FETCH with a static curso
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 144 and 145: 3.15.1 Installation commands. Of co
Page 146 and 147: Figure 3-47 Explain of the old cons
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Page 150 and 151: Figure 3-50 Suggested RUNSTATS stat
Page 152 and 153: Looking at the explanation, we can
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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 164 and 165: Regression is about 5% better than
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
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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
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Page 188 and 189: 4.2.3 Conclusion Nondistributed per
Page 190 and 191: Important: With PTFs UK04394 (DB2 V
Page 192 and 193: - DATASPACE BP CONTROL BLOCKS = 0 M
Page 194 and 195: The EXTENDED REGION SIZE (MAX) is t
Page 196 and 197: RDS OP POOL (MB) N/A RID POOL (MB)
Page 198 and 199: As you can now appreciate, it is im
Page 200 and 201: Megabytes A V7 Customer DBM1 Thread
Page 202 and 203: 4.5.1 Performance The most buffer p
Page 204 and 205: 4.6.1 Performance maintained in a 2
Page 206 and 207: 4.6.2 Conclusion We can conclude th
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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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