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

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You can keep the DBRMs in EBCDIC format if you use NEWFUN(NO), but you cannot use any new functions. 2.6.4 SUBSTRING function Once you go into ENFM and beyond, you can use the new V8 SUBSTRING built-in function, which is character-based. The old V7 SUBSTR function continues to be byte-based. DB2 V8, with APAR PQ88784, introduces a number of new “character-based” functions rather than the older “byte-based” functions. Some code pages have special characters that can now result in more than one byte in Unicode, so you may get different results using SUBSTRING. Make sure you use the right substring function to get the correct results. Several new functions are added and several existing functions are enhanced to allow the processing of character data in more of a "character-based" than "byte-based" manner. The new functions are: ► CHARACTER_LENGTH ► POSITION ► SUBSTRING The changed functions are: ► CHAR ► CLOB ► DBCLOB ► GRAPHIC ► INSERT ► LEFT ► LOCATE ► RIGHT ► VARCHAR ► VARGRAPHIC The new and changed functions allow you to specify the code unit in which the strings should be processed. That is, CODEUNITS determines how to interpret a character string. 2.7 New installation default values In this section, we list the changes that have taken place to the default values of several buffer pool threshold settings in DB2 V8. These new values are the result of system performance tuning work done by the DB2 Development Performance Department in SVL, and considerations related to a more general applicability of those values. They are applied to your system if you are doing a new install of DB2 and select not to specify the values yourself. If you are migrating to V8, and your parameter values are specified as the old defaults, then you should consider changing to the new values for improved performance and availability, particularly CACHEDYN and CHKFREQ. We also list the new DSNZPARM default values. These are changes to the defaults in the installation CLIST for DB2 V8 which affect your definitions if you are just letting the panels assume defaults. If this is the case, and you want to compare performance across V7 and V8 in compatibility mode, you might want to review the new values and set them back to the old defaults, at least for the initial period. 24 DB2 UDB for z/OS Version 8 Performance Topics
New buffer pool threshold values For the ALTER BUFFERPOOL statement, the initial default for the deferred write thresholds are: ► DWQT — buffer pool deferred write threshold as a percentage of the total virtual pool size. The new value is 30%. The default is decreased from the old value of 50%. ► VDWQT — buffer pool vertical deferred write threshold as a percentage of the total virtual pool size. The new value is 5%. The default is decreased from the old value of 10%. For the ALTER GROUPBUFFERPOOL statement the initial default for the deferred write thresholds are: ► CLASST — threshold for the class castout to disk as a percentage of the size of the data entries in the group pool. The new value is 30%. The default is decreased from the old value of 50%. ► GBPOOLT — threshold for the class castout as a percentage of the size percentage of the total virtual pool size. The new value is 5%. The default is decreased from the old value of 10%. ► GBPCHKPT — default for the GBP checkpoint interval in minutes. The new value is 4 minutes. The default is decreased from the old value of 8 minutes. Changes to default parameter values Table 2-1 summarizes the old and new DSNZPARM default values, sorted by PANEL ID. Table 2-1 Changed DSNZPARM default settings Macro Parameter Old value New value Panel Description DSN6FAC TCPKPALV ENABLE 120 sec. DSNTIP5 TCP/IP keepalive DSN6SYSP LOBVALA 2048 KB 10240 KB DSNTIP7 Storage value by user DSN6SPRM CACHEDYN NO YES DSNTIP8 Cache for dynamic SQL DSN6ARV BLKSIZE 28672 24576 DSNTIPA Archive log block size DSN6FAC IDTHTOIN 0 120 DSNTIPB Idle thread timeout DSN6SPRC SPRMINT 180 120 DSNTIPC DDF idle thread interval time out DSN6SPRM EDMDBDC N/A 102400 KB DSNTIPC EDM DBD cache DSN6SPRM EDMPOOL 7312 KB 32768 KB DSNTIPC EDM pool size DSN6SPRM EDMSTMTC N/A 102400 KB DSNTIPC EDM statement cache DSN6SYSP CONDBAT 64 10000 DSNTIPE Max number of remote connected users DSN6SYSP CTHREAD 70 200 DSNTIPE Max number of users DSN6SYSP IDBACK 20 50 DSNTIPE Max number of batch connections DSN6SYSP IDFORE 40 50 DSNTIPE Max number of TSO connections DSN6SYSP MAXDBAT 64 200 DSNTIPE Max number of remote active users Chapter 2. Performance overview 25
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ibm.com/redbooks Front cover DB2 UD
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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 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
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Page 48 and 49: application that can have great pot
Page 50 and 51: Because you can significantly incre
Page 52 and 53: The possible increase in thread foo
Page 54 and 55: 2.5.9 Unicode parser Important: Con
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
Page 102 and 103: V8 shows that PL is joined with CV
Page 104 and 105: 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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