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

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The SYSIBM.INDOUBT table and the package can be created by invoking the JCC In-Doubt utility. It is a prerequisite to manually run this utility as a user having SYSADM privileges against the DB2 V7 location in order to accomplish XA (global /distributed) transactions. The syntax is as follows: java com.ibm.db2.jcc.DB2T4XAIndoubtUtil -url jdbc:db2://:/ -user -password This has recently changed with PQ95881: Now you can run the "XAindoubt.." and the create of the indoubt table separately. 7.3.3 Miscellaneous items Java Data Types The Java language does not have a fixed length character string data type; every string is variable length. In DB2, on the other hand, in most cases, fixed length character columns defined as CHAR(n) are used. In DB2 V8 all predicates comparing string CHAR and VARCHAR data types with the same CCSID are stage 1 and indexable; even for unlike CCSIDs the predicate will still be stage 1 and indexable if the “column” side of it is in Unicode since all predicates that compare unlike CCSIDs are evaluated in the Unicode encoding scheme. KEEPDYNAMIC YES KEEPDYNAMIC specifies whether DB2 keeps already prepared dynamic SQL statements in the local dynamic statement cache after commit points. Bind a copy of the DB2 Universal Driver packages with a different collection id: ► KEEPDYNAMIC=YES ► collection= The keepDynamic connection and JdbcCollection property values for the DataSource specified must match the values that were specified when the bind was run. These values can be set using: ► The setXXX methods ► In a java.util.Properties value in the info parameter of a DriverManager.getConnection call ► The java.lang.String value in the url parameter of a DriverManager.getConnection call The following measurement was executed: WebSphere V5.0.2 on AIX was used to access DB2 for z/OS V8. The workload was using container managed persistence conforming to the SpecjApp2002 benchmark. The results are presented in Figure 7-18. 304 DB2 UDB for z/OS Version 8 Performance Topics
Trans/second - higher is better 250 200 150 100 50 0 9 % KeepDynamic YES 20 % ITR AIX ITR z/OS keepdyn no keepdyn yes Figure 7-18 DB2 Universal Driver - KEEPDYNAMIC YES SpecJApp2002 WebSphere/AIX V502- DB2 for z/OS V8 ITR = tps/cpu%*100 CPU is saved on the client (WebSphere) and in DB2 on the server. Throughput improved with 9% on the client and 20% on the DB2 server. In order to benefit from performance improvements the following PTFs/APARs should be applied: PQ86787/UQ87049, PQ87126/UQ88971 and PQ87129/UQ87633. Conclusion The statements are saved on thread level and can consume a significant amount of storage. Type 2 distributed threads cannot turn inactive and DB2 resources for distributed threads are not freed at commit. Therefore this is not recommended for storage constrained systems. Recommendation KEEPDYNAMIC(YES) is recommended for applications with a limited amount of SQL statements that are executed very often. It is not recommended for applications with a large number of SQL statements that are executed infrequently. LOB streaming In prior releases, Universal Clients and Linux, UNIX, and Windows servers had to read the entire LOB to determine its length prior to flowing it to DB2. LOB streaming, activated by the fullyMaterializeLobData property, allows the DB2 universal client or a DB2 for Multiplatforms server to not know the total length of a LOB value prior to sending a LOB value. This improves performance by eliminating the need to read the entire LOB to determine its length prior to sending the LOB value. DB2 continues to provide the total length of a LOB value, but it is now able to read in the LOB immediately without knowing the exact length up-front. The main benefit is performance. But there is another advantage. It is not always possible to determine a LOB's attributes (like length and nullness) up-front, for example when a client is acting on behalf of a CLI application that is being supplied with chunks of a LOB value in a piecemeal fashion using the SQLPutData API. Therefore this improvement provides a more flexible mechanism whereby the sender can defer indicating the nullness and/or the length of a LOB value until a chunk is ready to be sent. Chapter 7. Networking and e-business 305
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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
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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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--------------------------- -------
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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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Page 324 and 325: Recommendation If you currently do
Page 326 and 327: ► The DB2 Universal JDBC type 4 D
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Page 348 and 349: 7.6.3 Performance The following inf
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Page 354 and 355: Table 8-1 shows extracts from DB2 P
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Page 374 and 375: 9.1 Unicode catalog DB2 for z/OS su
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Page 380 and 381: From these measurements we observe
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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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DB2 UDB for z/OS Version 8 Performance Topics - IBM Redbooks

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