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

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The possible increase in thread footprint in migrating to V8 is currently estimated to be between 30% and 70%. This is based on the laboratory measurements thus far. For more information on the buffer pools in DB2 V8 and related performance implications, refer to Chapter 4, “DB2 subsystem performance” on page 127. 2.5.3 Increased number of deferred write, castout and GBP write engines As the storage constraints are lifted, the workload may increase. As a result, DB2 increases the maximum number of deferred write, castout and GBP write engines from 300 to 600. This increase should alleviate engine not available conditions. For more information on these write engines and their performance implications, refer to Chapter 4, “DB2 subsystem performance” on page 127. 2.5.4 EDM pool changes One of the largest virtual storage consumers is usually the EDM pool. With DB2 V7 some virtual storage relief was provided by the capability to move part of the EDM pool to a data space. Further enhancements are provided by DB2 V8. In this section we discuss: ► Dynamic statement cache ► DBD cache ► Plans, packages and DBDs For more information on the EDM pool and its performance implications, refer to Chapter 4, “DB2 subsystem performance” on page 127. Dynamic statement cache In DB2 V7 dynamic statements are cached in the dynamic statement cache only if the DSNZPARM CACHEDYN is turned on. In DB2 V8 caching is enabled by default (new install) and the dynamic statement cache is moved above the 2 GB bar. This can provide additional storage relief to the DBM1 address space in case a data space was not used. DBD cache In addition, a new DBD cache is created for the storage of DBDs and also allocated above the 2 GB bar. Segregating the DBDs from the EDM pool relieves contention from other objects in the EDM pool. DB2 V8 can support more and larger DBDs adding to DB2 V8’s scalability. Plans, packages, and DBDs Plans, packages, and DBDs are all stored in the directory. There is minimal performance overhead running in CM because DB2 plans, packages, and DBDs are different between V7 and V8. This overhead can be alleviated for plans and packages by rebinding them. We recommend rebinding anyway to take advantage of V8 access path improvements, avoid conversions and enable faster processing. Important: Rebind plans and packages once you are comfortable with CM. If you can live with the overhead during CM and cannot rebind twice, then rebind once you are in NFM. 20 DB2 UDB for z/OS Version 8 Performance Topics
2.5.5 Fast log apply Once you migrate to DB2 V8 CM, the new default for fast log apply (FLA) is 100 MB. This should have a minimal effect on DBM1 storage. FLA is used by the RECOVER utility, during restart of a failed DB2, or when RESTORE SYSTEM is used. The storage is allocated when needed and released when the FLA phase is complete. When multiple RECOVER utility jobs are run in parallel, DB2 can take advantage of FLA for up to 10 concurrent jobs, each utilizing 10 MB. The default value for FLA at restart is always 100 MB, even if you explicitly specify 0 in the DSNTIPL panel or in the DSNZPARM LOGAPSTG. During RESTORE SYSTEM, a new utility with DB2 V8, the default value for FLA (if LOGAPSTG is not zero) is 500 MB. For more information on FLA and its performance implications, refer to Chapter 4, “DB2 subsystem performance” on page 127 and Chapter 5, “Availability and capacity enhancements” on page 217. 2.5.6 Multi-row operations with DRDA 2.5.7 IRLM V2.2 DB2 V8 CM automatically exploits multi-row fetch when you use a remote client that uses block-fetching in a distributed application. The DDF address space uses multi-row fetch to build the blocks of data to be sent to the client. This implies you do not have to change the application to take advantage of this tremendous performance enhancement. We have experienced performance improvements in these client applications in DB2 V8 CM. For more information on the multi-row fetch operations with DRDA, refer to Chapter 7, “Networking and e-business” on page 281. The IRLM address space also changes with DB2 V8 and supports 64-bit virtual addressing. The IRLM is able to support more concurrent locks. PC=YES is now enforced when you migrate to DB2 V8. The ECSA usage (PC=NO) capability can still be specified, but is no longer used by V8. Therefore, the ECSA previously used for IRLM, if you used PC=NO, could now be available for use by other applications. Important: If you used PC=NO, review your ECSA usage, since potentially there can be less of a need for ECSA with IRLM V2.2. Real storage for IRLM locks increases significantly, since they have doubled in size. For more information on the IRLM in 64-bit mode, refer to Chapter 4, “DB2 subsystem performance” on page 127. 2.5.8 Page-fixed buffer pools DB2 V8 introduces a new buffer pool parameter called PGFIX which allows you to choose to fix buffer pools in real storage. Before reading or writing a page, DB2 must fix the page in real storage in order to perform the I/O. In DB2 V8, with this new buffer pool option, you can decide to permanently page fix an entire buffer pool. The option to page fix a buffer pool is available in CM, but is not automatically enabled. Chapter 2. Performance overview 21
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 . . . .
Page 12 and 13: x DB2 UDB for z/OS Version 8 Perfor
Page 14 and 15: 3-48 Consistency query - 31 New . .
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Page 18 and 19: 8-5 CF Request Batching - DB2 CPU .
Page 20 and 21: xviii DB2 UDB for z/OS Version 8 Pe
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 42 and 43: In this chapter we anticipate the a
Page 44 and 45: 2.1.3 I/O time 2.1.4 Virtual storag
Page 46 and 47: ► The performance benchmarks for
Page 48 and 49: application that can have great pot
Page 50 and 51: Because you can significantly incre
Page 54 and 55: 2.5.9 Unicode parser Important: Con
Page 56 and 57: You can keep the DBRMs in EBCDIC fo
Page 58 and 59: Macro Parameter Old value New value
Page 60 and 61: 28 DB2 UDB for z/OS Version 8 Perfo
Page 62 and 63: ► Parallel sort enhancement Paral
Page 64 and 65: Characteristics of the host variabl
Page 66 and 67: 3.1.4 Performance Update 10 rows us
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
Page 84 and 85: EVE.EXT = 'ADD BILL' AND EVE.TXC =
Page 86 and 87: Star Schema Figure 3-15 Star schema
Page 88 and 89: merge joins and work file usage. DB
Page 90 and 91: Star join access path without a spa
Page 92 and 93: 3.3.4 Performance Sparse index for
Page 94 and 95: V8 Star Join Access Path Figure 3-2
Page 96 and 97: 3.3.5 Conclusion Star join workload
Page 98 and 99: . SELECT * FROM PAOLO.TORDER WHERE
Page 100 and 101: 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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