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

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KB 600 500 400 300 200 100 0 Figure 4-5 DBM1 user thread storage comparison DB2 V7 vs. V8 OTHER includes RDS OP pool (in V7 only), RID pool, and trace tables. This graph shows that, in general, the DBM1 storage required for each thread increases as we move from DB2 V7 to V8. Comparing this graph with Figure 4-4, we can conclude the increase in thread storage is the most significant driver for the overall storage increase in the DBM1 address space, as we move from DB2 V7 to V8 with distributed applications. For dynamic SQL, here we can see that more storage is required by DB2 V8 to prepare the dynamic SQL. Once again, this increase in storage is needed to support DB2 functionality such as processing SQL in Unicode and support for long names. We also observe that the dynamic statement cache (DSC) memory usage has increased. Tip: PTF UK00991for APAR PQ96772 provides significant virtual storage relief for large, dynamic SQL cache environments by moving the DSC control blocks above the bar. DIST address space Now, let us turn our attention briefly to the DIST address space, since the total DB2 demands on storage extend beyond the DBM1 address space. Table 4-6 on page 150 compares the virtual storage consumed by active distributed connections in the DIST address space for DB2 V7 and V8 for all distributed workloads we studied. The table shows quite a significant increase in virtual storage used by active distributed connections in the DIST address space, from 45% to 169% for SQLJ and JDBC workloads respectively. This increase may not be an issue with distributed inactive thread processing (CMTSTAT=INACTIVE). The majority of this growth is stack storage and the variable subpools. These are very dynamic pools with the storage owned and consumed by thread-related activities. 152 DB2 UDB for z/OS Version 8 Performance Topics DBM1 below 2 GB VS User Thread Storage Comparison V7 CLI V8 CLI V7 JDBC V8 JDBC V7 EMB V8 EMB V7 SQLJ V8 SQLJ V7 IRWW V8 IRWW V7 IRWW DSHR V8 IRWW DSHR Other Stack DSC User
Thread-related storage is much larger in V8 to support all the new function consumed by threads. The main driver is support for much larger identifiers within DB2. IRLM address space IRLM V2.2 which is shipped with DB2 V8, is now a 64-bit application in which the locks now always reside above the 2 GB bar. These changes also have a significant impact on virtual storage used by DB2, if you currently specify PC=NO. Refer to 4.6, “IRLM V2.2” on page 171, for a more detailed discussion of IRLM and virtual storage. MSTR address space The MSTR address space has not caused any problems related to being virtual storage-constrained. In addition, the MSTR address space is still all coded as 31-bit. We therefore have not done any specific studies on virtual storage usage of the MSTR address space in V8 compared with V7. Real storage An implication of the z/OS implementation of the z/Architecture in 64-bit mode is there is no more Expanded Storage. If a page or ‘frame’ needs to be paged out of real memory by the system, it is paged out directly to disk. This can have an extraordinary impact on DB2 performance, especially if the buffer pools, or part of the buffer pools, are paged out to auxiliary storage. DB2 V8 requires more virtual storage to accommodate: ► Bigger modules, control blocks, and working storage ► Higher default and maximum buffer pool size, RID pool size, sort pool size, EDM pool size and authorization cache ► More and larger user threads ► More deferred write engines and castout engines (300 -> 600 maximum) ► More parallelism enabled ► Locks moved above the 2 GB bar This increased demand for virtual storage therefore increases the demand on the amount of real (or main) storage that is available on the system (maximum 512 GB on a z9 EC model S38 or S54) or LPAR (maximum 128 GB). There are messages regarding what storage is currently available but the storage information contained in these messages can be overly optimistic. The real storage is by z/OS image or LPAR, and you could have several other DB2 subsystems, each contending for the same real storage. The messages are documented in Table 4-7. Table 4-7 DB2 storage messages Message Message information DSNB536I Indicates that the total buffer pool virtual storage requirement exceeds the size of real storage capacity of the z/OS image. DSNB610I Indicates that a request to define or increase the size of the buffer pool exceeds the smaller of twice the amount of real storage of the z/OS image or 1 TB. DSNB508I Issued when the total size used by all buffer pools exceeds 1 TB. Chapter 4. DB2 subsystem performance 153
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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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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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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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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
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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
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
Page 172 and 173: Frees up space below the bar for ot
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Page 176 and 177: So, we advise you to not overalloca
Page 178 and 179: See 4.3, “Monitoring DBM1 storage
Page 180 and 181: Table 4-4 System storage configurat
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Page 186 and 187: For the same buffer pool size and o
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
Page 208 and 209: service for Unicode conversions, an
Page 210 and 211: overcome this, when DB2 Connect is
Page 212 and 213: INSERT HV1 1200 HV2 1200 SELECT HV1
Page 214 and 215: AIX C-program Conversion Routines P
Page 216 and 217: 4.7.1 Performance The improvements
Page 218 and 219: In October 2003, a new enhancement
Page 220 and 221: UseServerEncoding data source prope
Page 222 and 223: 4.8.1 Performance 4.8.2 Conclusion
Page 224 and 225: Multilevel security with row-level
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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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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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DB2 UDB for z/OS Version 8 Performance Topics - IBM Redbooks

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