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

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This record is activated by: -START TRACE(PERFM) CLASS(32) IFCID(342) Monitors, for example, can trigger exceptions on this new IFCID to catch runaway queries before they monopolize the system and cause other applications to fail, because the workfile database and TEMP database are shared amongst all DB2 users. Obtaining secondary authorization ID information This enhancement allows applications to obtain the authorization identifiers that are associated with an application (such as QMF) that is executing. The primary authorization ID, the CURRENT SQLID, and secondary authorization IDs can be retrieved with a synchronous read of IFCID 234. This enhancement is also available in DB2 V6 and V7 via APAR PQ47973, PTF UQ57178 for V7 and PTF UQ57177 for V8. Note however that IFCID 234 is always started implicitly by DB2 at startup time. It is not contained in any DB2 trace class and cannot be specified as an IFCID value on the -START TRACE command. Auditing for multilevel security Audit record (IFCID 142) is produced if a table with a security label is created, altered or dropped. The user must be identified to Security Server with a valid SECLABEL. If not, an authorization error and audit record are produced (IFCID 140). 4.12.7 Miscellaneous trace enhancements In this section we discuss other enhancements to monitoring, such as new DB2 messages. Monitor system checkpoints and log offload activity DB2 V8 provides new messages, as well as an IFCID 335 record, to help you to identify problems with log offloading faster. An IFCID 335 record is produced if the statistics class 3 trace is active. See “Monitoring system checkpoints and log offload activity” in DB2 UDB for z/OS Version 8: Everything You Ever Wanted to Know, ... and More, SG24-6079, for more information about the console messages that are produced. This enhancement helps you identify potential problems with DB2 logging before they become real problems which may cause application outages. For example, when DB2 stops taking system checkpoints or gets stuck during its log offload activity, the system grinds to a halt. 4.13 Miscellaneous items In this section we introduce miscellaneous enhancements which also impact DB2 subsystem availability, performance and scalability. 4.13.1 DB2 logging enhancements As the throughput of a single DB2 subsystem increases, the amount of data DB2 must log also increases. Keeping the DB2 logging data available and online is very important, as it dramatically speeds up DB2 recovery and maximizes data availability. 212 DB2 UDB for z/OS Version 8 Performance Topics
DB2 V8 in new-function mode increases the number of active log data sets from 31 to 93, allowing DB2 to keep more log data online and therefore available for any recovery. In addition, DB2 V8 in new-function mode increases the number of archive log data sets DB2 remembers from 1,000 to 10,000. This increases the amount of log data DB2 is able to access and use in recovery, therefore satisfying the larger window often required by Service Level Agreements (SLA). 4.13.2 Up to 65,041 open data sets DB2 V8 increases the number of open data sets from 32k to 65,041. This enhancement is available starting with z/OS V1.5 base code. Open data sets require storage for MVS control blocks below the 16 MB line. This has been the cause of virtual storage constraint problems below the 16 MB line in the past. Dynamic allocations can request these control blocks to be allocated above the 16 MB line. With z/OS V1.5, media manager, the interface that DB2 uses, can fully exploit this feature. This reduces the amount of storage that DB2 requires below the 16 MB line. This enhancement does not only provide virtual storage relief. It also removes a potential scalability problem with growing systems and growing machine capacity. In addition, DB2 V8 no longer uses system-generated DDNAMEs, as the current limit there is also 32k. DB2 generates its own DDNAMEs for dynamic allocation. This way DB2 can have better open data set performance as well, and, can avoid the problem of the task that generates the system DDNAMEs becoming a bottleneck for parallel data set open. When DSMAX is reached, DB2 currently attempts to close up to 3% of the open data sets. However, 3% of 65,041 is still a large number, and this burst of data set close activity could be disruptive. Therefore DB2 now closes MIN(3%,300) data sets when DSMAX is reached. PFT UQ96862 for APAR PQ96189 is related to the number of open data sets. 4.13.3 SMF type 89 record collection enhancements SMF type 89-1 interval records provide IBM with the required “Software Usage Report” for reporting on zSeries Software License Requirements. Prior to V8, DB2 automatically used detailed tracking of measured usage if SMF type 89 records were activated. DB2 V8 provides a new DSNZPARM parameter, SMF89, which lets you specify whether DB2 is to do detailed tracking for measured usage pricing. The default value is NO, which means that DB2 does not do detailed measured usage tracking. If the SMF type 89 record is activated, only high-level tracking is recorded in the SMF type 89 record. If you select YES, DB2 does detailed measured usage tracking if SMF type 89 records are activated. When SMF89 is set to YES, DB2 invokes a z/OS service on every entry or exit into or out of DB2 to ensure accurate tracking. A new SMF type 89 record is cut on each SQL statement. If you select NO, DB2 CPU is reduced; however, the amount of time spent in DB2 as measured by SMF 89 is increased. A "typical" CPU overhead for DB2 performing detailed tracking of CPU usage is in the range of 0 to 5%. Since there is a fixed overhead per SQL statement, the overhead tends to be higher for short-running SQL statements and negligible for long-running SQL statements. For Chapter 4. DB2 subsystem performance 213
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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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Page 196 and 197: RDS OP POOL (MB) N/A RID POOL (MB)
Page 198 and 199: As you can now appreciate, it is im
Page 200 and 201: Megabytes A V7 Customer DBM1 Thread
Page 202 and 203: 4.5.1 Performance The most buffer p
Page 204 and 205: 4.6.1 Performance maintained in a 2
Page 206 and 207: 4.6.2 Conclusion We can conclude th
Page 208 and 209: service for Unicode conversions, an
Page 210 and 211: overcome this, when DB2 Connect is
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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
Page 228 and 229: DB2 must call RACF for this dominan
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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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 258 and 259: 5.1.2 Conclusion The BACKUP SYSTEM
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
Page 282 and 283: Load table of 20M rows, 10 partitio
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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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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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