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

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– CLASST: Specifies the threshold at which class castout is started. It is expressed as a percentage of the number of data entries. The default is decreased from 10% to 5%. – GBPOOLT: Specifies the threshold at which the data in the group buffer pool is cast out to DASD. It is expressed as a percentage of the number of data entries in the group buffer pool. The default is decreased from 50% to 30%. – GBPCHKPT: Specifies the time interval in minutes between group buffer pool checkpoints. The default is lowered from 8 minutes to 4 minutes. 9.2 IVP sample programs DB2 continues to enhance the IVP samples in order to demonstrate the usage of new functions, to provide more features and enhance the usability of the samples themselves. In this section we are interested in the performance of multi-row fetch from the programs DSNTEP2, DSNTEP4 and DSNTIAUL. This function can be activated only in NFM. These programs are often used for testing during the migration to a new DB2 release. Performance measurements In this section we describe how the tests were made, what kinds of scenarios were used, how we get the default, and how much improvement each program gets when using multi-row FETCH. Native measurements environment ► DB2 for z/OS V8 and V7 (non-data sharing) ► z/OS Release 1.3.0 ► IBM z900 Series 2064 2-way processor ► ESS 800 DASD with FICON channels Measurement scenarios ► Non-partitioned table space, 10,000 row table, 26 columns, 1 index ► Dynamic SQL with table space scan ► Measured on both V7 and V8 ► Retrieve 5 columns, 10k rows ► Retrieve 20 columns, 10k rows DSNTEP2 and DSNTEP4 DSNTEP2 is a PLI program shipped with DB2 to demonstrate the support for dynamic SQL. The DSNTEP2 has been enhanced for: ► GET DIAGNOSTICS DSNTEP2 now uses GET DIAGNOSTICS to retrieve error information. ► Large SQL statement: The sample program DSNTEP2 can now handle SQL statements larger than 32 KB in size. ► Greater than 18 character table/column names: The sample program DSNTEP2 has been modified to handle the longer table and column names. ► New MAXERRORS value: A new MAXERRORS parameter has been added in DSNTEP2. It allows you to dynamically set the number of errors that DSNTEP2 will tolerate. In previous versions of DB2, DSNTEP2 stopped processing after it encountered 10 SQL errors. The 346 DB2 UDB for z/OS Version 8 Performance Topics
MAXERRORS value can be modified during run time by coding the following functional comment in the SQL statements: SET MAXERRORS ► SYSPRINT blocking in DSNTEP2: A change to SYSPRINT blocking in DSNTEP2 will speed up the rate in which DSNTEP2 outputs its results. The blocking size was very small before, thus impacting the performance when processing large result sets. DSNSTEP2 can now also use the system default or user assigned JCL block size. A new sample program, DSNTEP4, has been added. It is like DSNTEP2, but it uses multi-row FETCH. In Figure 9-2 we show measurements of the new DSNTEP4 using different multi-row settings, and we compare them to DSNTEP2 (not using multi-row). Class 1 CPU Time (MSEC) Multi-row Fetch support of DSNTEP4 (10,000 rows fetched / test) 900 600 300 0 V7 V8 Ran with different number of rows in a FETCH call Figure 9-2 Multi-row fetch support of DSNTEP4 As mentioned, DB2 V8 ships DSNTEP2 and DSNTEP4. DSNTEP4 uses multi-row FETCH. You can specify a new parameter, MULT_FETCH, to specify the number of rows that are to be fetched at one time from the result table. The default fetch amount for DSNTEP4 is 100 rows, but you can specify from 1 to 32,676 rows. It can be coded as a functional comment statement as follows: //SYSIN DD * --#SET MULT_FETCH 5895 SELECT * FROM DSN8810.EMP; V8 mr=10 V8 mr =100 In Figure 9-3 we show a comparison of DSNTEP2 with DSNTEP4. V8 w/o MR : +5% to +7% V8 with MR : -5% to -35% 5 columns 20 columns V8 mr=1000 V8 mr=10000 Chapter 9. Installation and migration 347
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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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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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Page 336 and 337: The SYSIBM.INDOUBT table and the pa
Page 338 and 339: Batch updates A batched update is a
Page 340 and 341: Example In DB2 V8 SQL/XML publishin
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Page 348 and 349: 7.6.3 Performance The following inf
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Page 352 and 353: Impact on coupling facility: You do
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Page 374 and 375: 9.1 Unicode catalog DB2 for z/OS su
Page 376 and 377: that all applications are converted
Page 380 and 381: From these measurements we observe
Page 382 and 383: Class 1 CPU time (MSEC) 200 150 100
Page 384 and 385: dynamic statement cache. If activat
Page 386 and 387: that everything is ready. This step
Page 388 and 389: Table Number of rows SYSDATABASE 75
Page 390 and 391: In Figure 9-7 we describe the perfo
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Page 394 and 395: Query 35 36 Old DSNTESQ CPU 1 hr 1
Page 396 and 397: 10.1 DB2 Estimator DB2 Estimator V8
Page 398 and 399: - REAL AND AUXILIARY STORAGE This i
Page 400 and 401: Another use is during back out of a
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Page 410 and 411: A.1 Maintenance for DB2 V8 The APAR
Page 412 and 413: APAR # Area Text PTF and Notes PQ88
Page 416 and 417: APAR # Area Text PTF and Notes PK21
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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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