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

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RDS OP POOL (MB) N/A RID POOL (MB) 0.35 PIPE MANAGER SUB POOL (MB) 0.00 LOCAL DYNAMIC STMT CACHE CNTL BLKS (MB) 3.93 THREAD COPIES OF CACHED SQL STMTS (MB) 29.10 IN USE STORAGE (MB) 16.13 STATEMENTS COUNT 2096 HWM FOR ALLOCATED STATEMENTS (MB) 16.13 STATEMENT COUNT AT HWM 2096 DATE AT HWM 10/23/04 TIME AT HWM 00:59:04.55 BUFFER & DATA MANAGER TRACE TBL (MB) N/A TOTAL FIXED STORAGE (MB) 0.46 TOTAL GETMAINED STACK STORAGE (MB) 71.28 STORAGE CUSHION (MB) 123.79 DBM1 STORAGE ABOVE 2 GB QUANTITY REAL AND AUXILIARY STORAGE QUANTITY -------------------------------------------- ------------------ -------------------------------------------- ------------------ FIXED STORAGE (MB) 0.02 REAL STORAGE IN USE (MB) 694.48 GETMAINED STORAGE (MB) 2221.78 AUXILIARY STORAGE IN USE (MB) 0.00 COMPRESSION DICTIONARY (MB) 0.00 CACHED DYNAMIC SQL STATEMENTS (MAX) (MB) 1024.00 DBD CACHE (MAX) (MB) 1024.00 VARIABLE STORAGE (MB) 173.78 VIRTUAL BUFFER POOLS (MB) 468.75 VIRTUAL POOL CONTROL BLOCKS (MB) 0.14 CASTOUT BUFFERS (MB) 0.00 STAR JOIN MEMORY POOL (MB) 0.00 The TOTAL GETMAINED STORAGE has decreased from 599.18 MB in V7 to 236.09 MB in V8. This is a direct result of buffer pools, buffer pool control blocks, data space lookaside buffers, castout buffers and compression dictionaries all moving above the bar. We can see them now recorded in a new area of the report, titled DBM1 STORAGE ABOVE 2 GB. You will also notice these fields are now marked as N/A under the TOTAL GETMAINED STORAGE section of the report. For V8, RID Pool is only referred to RID map, since RID lists have been moved above the bar. Note that the RDS OP pool is recorded as N/A for V8. In DB2 V7, there was a single RDS OP pool reported, which all threads use. However in DB2 V8, the RDS OP pool storage for each thread is allocated from the thread's variable length storage pool. We can see the TOTAL GETMAINED STACK STORAGE jump from 26 MB to 71 MB. This increase is primarily due to larger thread-related structures in V8, since they must be larger to accommodate long names. So, in V8 we see a considerable decrease in TOTAL GETMAINED STORAGE and a considerable increase in TOTAL GETMAINED STACK STORAGE. DB2 V8 also breaks down the THREAD COPIES OF CACHED SQL STMTS storage into more meaningful statistics. Cached SQL statements for dynamic SQL can cause quite a lot of virtual storage to be consumed. ► THREAD COPIES OF CACHED SQL STMTS reports the virtual storage consumed by copies of currently executable SQL statements and the executable statements that are kept beyond commit when KEEPDYNAMIC YES is used. ► IN USE STORAGE reports the amount of virtual storage that is actually allocated to locally cached dynamic SQL statements, discounting storage not used in the storage allocation segment. ► STATEMENTS COUNT is the number of locally cached dynamic SQL statements that are actually using the storage. The following formula can give you some insight into the degree of fragmentation of storage which is used to locally cache dynamic SQL statements. (THREAD COPIES OF CACHED SQL STMTS - IN USE STORAGE) / STATEMENTS COUNT 164 DB2 UDB for z/OS Version 8 Performance Topics
In addition, DB2 shows a high water mark for storage consumed by locally cached dynamic SQL statements. The high water marks are measured since the last time the IFCID 225 record was externalized. Now, with DB2 V8, if you look only at virtual storage, you get a partial view. DB2 V8 now can allocate very large amounts of virtual storage above the bar which may not be backed by real memory. This can be very bad for performance. The DBM1 STORAGE ABOVE 2 GB counters do not provide the whole picture. So the IFCID 225 record and DBM1 Storage Statistics section of the DB2 PE Statistics reports also report on DBM1 Storage usage above the 2 GB bar, as well as provide an indication of real storage frames used by the DBM1 address space. These statistics are displayed for both DB2 V7 and DB2 V8. REAL STORAGE IN USE reports on the amount of real storage in megabytes, used by the DBM1 address space. Ideally, this should be significantly less than the amount of virtual storage consumed. (TOTAL DBM1 STORAGE BELOW 2 GB + all the counters in TOTAL DBM1 STORAGE ABOVE 2 GB.) AUXILIARY STORAGE IN USE is the amount of storage in megabytes the DBM1 address space has allocated in auxiliary storage (disks). This should be zero or very close to it. The following points are indicators DB2 may be suffering from storage-related problems, such as a DB2 code error (storage leak) or a really stressed system due to a lack of real storage: ► 100% real frames consumed. Note that although a physical machine may have 30 GB of real storage, a given LPAR may only have a fraction of this real storage dedicated. ► An excessive number of auxiliary paging slots in use. ► A general performance degradation. Dumps are also another useful tool to monitor storage usage within the DBM1 address space. However, they only capture a point-in-time picture of storage usage and do not capture peaks. An IPCS formatted dump using the parameter VERBEXIT DSNWDMP ‘ALL SM=3’ produces the useful summary of DBM1 storage usage shown in Example 4-3. Example 4-3 DBM1 storage usage summary ===Stack(SKB) total: 55196K 53M ===Fixed subpool total: 384K 0M GMB total: 151755K 148M ADMF AGL system total: 3076K 3M ADMF AGL non system total: 93360K 91M ADMF AGL 31 total: 72064K 70M ADMF AGL VL total: 24372K 23M ADMF local total: 96436K 94M SQL cache total: 16080K 15M Variable subpool total: 119736K 116M Var+Fix+GMB+Stack total: 327071K 319M ===Above the bar Fixed subpool total: 2604K 2M ADMF AGL 64 total: 76072K 74M ADMF AGL 64 system total: 0K 0M Variable subpool total: 154616K 150M VSAS blocks: 2201M Chapter 4. DB2 subsystem performance 165
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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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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
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 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
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
Page 180 and 181: Table 4-4 System storage configurat
Page 182 and 183: Stack 11356 21033 85% 8648 19799 12
Page 184 and 185: KB 600 500 400 300 200 100 0 Figure
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 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
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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
Page 226 and 227: ► The security level that defines
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Page 230 and 231: 4.9.2 Conclusion The CPU increase c
Page 232 and 233: 4.10.1 Performance VSAM does not kn
Page 234 and 235: 4.10.2 Conclusion 4.10.3 Striping A
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Page 240 and 241: This message is completed with the
Page 242 and 243: This enhancement is introduced by P
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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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