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

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5.1.2 Conclusion The BACKUP SYSTEM utility provides an easier and minimally disruptive way to backup an entire DB2 subsystem or data sharing group. Executing the BACKUP SYSTEM utility concurrent with your workload should not impact the performance. 5.1.3 Recommendations We recommend that you execute the FRBACKUP prepare command outside the actual backup cycle in order to minimize the impact on the backup elapsed time. Fast log apply supports the system level point-in-time recovery and provides good performance. We highly recommend to activate fast log apply (LOGAPSTG DSNZPARM parameter), your system will benefit from it, not only the RESTORE SYSTEM utility but also during all RECOVER utility executions and at DB2 restart. Individual recovery actions at the table space or index space level cannot use a BACKUP SYSTEM backup which implies these recoveries need a data set level copy. This data set level copy can be a DB2 image copy or a non DB2 backup (log only recovery), for example, a data set level FlashCopy backup (FlashCopy V2 required). 5.2 Automated space management In general, a large percentage of your data sets are today managed with DFSMS storage pools, reducing the workload and the interaction of your DB2 database administrators and storage administrators. Only the most critical data, as defined with service level agreements or as revealed by monitoring, may require special attention. Using DFSMS, the DB2 administrator gains the following benefits: ► Simplified data allocation ► Improved allocation control ► Improved performance management ► Automated disk space management ► Improved data availability management ► Simplified data movement An important function, automated data set space management, was still lacking in this list. DB2 provides this functionality in Version 8. The idea is that DB2 will adjust the size of the secondary extent, when extending the data set, in such a way that the maximum allowable data set size is reached, before the maximum number of extents for that data set is reached, therefore avoiding out of space conditions. Remember that today space allocation supports a maximum number of 255 extents per component of a VSAM data set for multivolume data sets and a maximum of 123 extents for a single volume allocation. A striped VSAM data set can have up to 255 extents per stripe. Also new in DFSMS for z/OS 1.5 is that the system consolidates adjacent extents for a VSAM data set when extending the data set on the same volume. Users of DB2 receive out of extent errors during data set extend processing when the maximum number of extents is reached, thus preventing a DB2 managed page set from reaching maximum data set size. Although DB2 issues warning messages (DSNP001I) of impending space shortage, user procedures in many cases cannot react quickly enough to spot the problem, use SQL ALTER to modify PRIQTY and SECQTY values, and then schedule a REORG. This is a significant problem today for large users of DB2, particularly for 226 DB2 UDB for z/OS Version 8 Performance Topics
users of ERP and CRM vendor solutions and ported applications with not well known growth, and can lead to application outages. Default PRIQTY and SECQTY values and often user provided PRIQTY and SECQTY values are too small, resulting in track allocation rather than cylinder allocation. As a result the performance of SQL SELECT and INSERT processing can be penalized by 2x or more. The first objective of this enhancement is to avoid the situation where a DB2 managed page set reaches the VSAM maximum extent limit of 255 before it can reach the maximum data set size which may be less than 1 GB or 1 GB, 2 GB, 4 GB, 8 GB, 16 GB, 32 GB or 64 GB. The second objective of the enhancement is to remove the need for a user to specify the secondary quantity for a DB2 managed page set, or even both the primary and secondary quantities, either when creating it initially or by using an ALTER statement later. The overall goal is to provide a solution which would benefit all users of DB2 in terms of improved DBA productivity and preventing application outages. DB2 V8 adds a new DSNZPARM parameter called MGEXTSZ (with a global scope) which enables the use of a “sliding secondary space allocation” for DB2 managed data sets (STOGROUP defined). The values are: NO and YES. The default value for MGEXTSZ is NO. The enhancement will help to reduce the number of out of space conditions, eliminate need for PRIQTY and SECQTY specification on SQL CREATE, improve user productivity, and avoid the performance penalty associated with small extent sizes. This patented solution should benefit all users of DB2, not just for ERP and CRM solutions, ported and new applications. It delivers autonomic selection of data set extent sizes with a goal of preventing out of extent errors before reaching maximum data set size. An increasing secondary quantity size up to 127 extents is allocated and a constant number of 559 cylinders for 32 GB and 64 GB data sets is used thereafter. Figure 5-6 shows the sliding scale mechanism for 64 GB data sets with 255 extents. It assumes an initial extent of 1 cylinder. Extent Size (CYLS) 600 500 400 300 200 100 0 16 Sliding scale for 64 GB data sets 32 Figure 5-6 Sliding scale for 64 GB data sets 64 96 128 255 Extent Number Chapter 5. Availability and capacity enhancements 227
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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
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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
Page 208 and 209: service for Unicode conversions, an
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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
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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
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Page 240 and 241: This message is completed with the
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Page 246 and 247: an online transaction with very sim
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Page 250 and 251: 5.1 System level point-in-time reco
Page 252 and 253: BACKUP SYSTEM During backup DB2 rec
Page 254 and 255: Figure 5-1 FRBACKUP PREPARE elapsed
Page 256 and 257: Figure 5-4 BACKUP SYSTEM FULL measu
Page 260 and 261: Figure 5-7 shows the sliding scale
Page 262 and 263: Maybe you have implemented a space
Page 264 and 265: For dynamically prepared queries, D
Page 266 and 267: ► CHAR(8) to VARCHAR(8) ► CHAR(
Page 268 and 269: Before ALTER INDEX add column, a ta
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Page 272 and 273: Percent of index pages Avg. Index L
Page 274 and 275: 300 250 200 time in seconds 150 100
Page 276 and 277: REORG REBALANCE We executed and mea
Page 278 and 279: 5.4 Volatile table 5.4.1 Conclusion
Page 280 and 281: If explicit clustering for a table
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Page 286 and 287: RUNSTATS INDEX PARTITION of a DPSI
Page 288 and 289: Note that when the qualified partit
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Page 292 and 293: 5.6.10 Support for more than 245 se
Page 294 and 295: 6.1 Online CHECK INDEX Online CHECK
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Page 298 and 299: - SORT 6 indexes in parallel - CHEC
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Page 302 and 303: 6.3 LOAD and UNLOAD delimited input
Page 304 and 305: 6.3.2 Conclusion We measured the CP
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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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