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

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dynamic statement cache. If activated, consider this usage when calculating your EDM pool size. See “Calculating the EDM pool space for the prepared-statement cache” of the DB2 UDB for z/OS Version 8 Installation Guide, GC18-7418, for details about estimating storage. If you specify YES, you must specify YES for USE PROTECTION on panel DSNTIPP. ► Fast log apply enabled by default LOG APPLY STORAGE is an option on panel DSNTIPBA. The acceptable values are: 0 to 100 MB. The macro is DSN6SYSP LOGAPSTG. The value in this field represents the maximum ssnmDBM1 storage that can be used by the fast log apply process. The default value is 0 MB, which means that the fast log apply process is disabled except during DB2 restart. During DB2 restart, the fast log apply process is always enabled and a value of 100 MB is assumed. The value you specify, if not equal to zero, which disables the function, is used for RECOVER utility executions. Since RECOVER jobs are likely to run in parallel, specify 100 MB so you can also use 10 MB of log apply storage for each concurrent RECOVER job (up to 10) that you want to have faster log apply processing. FLA is also utilized by the new RESTORE utility. In this case the default assumed by DB2 will be 500 MB, unless disabled by the value zero in LOG APPLY STORAGE. ► The data set size panel DSNTIP7 has four new fields which change the way DB2 manages VSAM data sets: – Vary DS control interval (2 fields were changed) – Optimize extent sizing – Table space allocation and index space allocation ► The Performance and Optimization panel, DSNTIP8, provides the defaults for two new special registers which have been created to support Materialized Query Tables: – CURRENT REFRESH AGE Specifies the default value to be used for the CURRENT REFRESH AGE special register when no value is explicitly set using the SQL statement SET CURRENT REFRESH AGE. The values can be 0 or ANY. The default of 0 disables query rewrite using materialized query tables. – CURRENT MAINT TYPES Specifies the default value to be used for the CURRENT MAINTAINED TABLE TYPES FOR OPTIMIZATION special register when no value is explicitly set using the SQL statement SET CURRENT MAINTAINED TABLE TYPES FOR OPTIMIZATION. Acceptable values are NONE, SYSTEM, USER, and ALL. The default (SYSTEM) allows query rewrite using system-maintained materialized query tables when the CURRENT REFRESH AGE is set to ANY. Alternatively, specifying USER allows query rewrite using user-maintained materialized query tables when CURRENT REFRESH AGE is set to ANY, and specifying ALL means query rewrite using both system-maintained and user-maintained materialized query tables. For materialized query tables refer to 3.2, “Materialized query table” on page 39. There are several other changes including: ► Checkpoint frequency increased from 50,000 to 500,000 log records ► Archive log block size reduced from 28672 to 24576 (for better DASD occupancy) ► Remove hiperpool definitions and VPTYPE settings. They are no longer supported in V8 ► DDF panels have new terminology 352 DB2 UDB for z/OS Version 8 Performance Topics
9.4 Migration – Use “Inactive DBAT” instead of “Type 1 Inactive Thread” – Use “Inactive Connection” instead of “Type 2 Inactive Thread” ► CCSIDs must be specified for EBCDIC, ASCII and Unicode even when you do not use those encoding schemas in your application ► The DSNHDECP module must be defined by the user. It is not defined by DB2 by default. ► Buffer pools BP8K0, BP16K0, and BP32K must be defined in advance since some catalog table spaces use 8 KB, 16 KB and 32 KB pages. ► For data sharing groups: GBP8K0, GBP16K0 and GBP32K also need to be allocated. ► The location name must be specified, even if DDF is not used. See PTF UQ90701 for APAR PQ91009. Migration is the process of converting an existing DB2 subsystem, user data, and catalog data to a new version. This process has changed from DB2 V7 to V8 in order to minimize the possible impact of regression and fallback incompatibilities. For more information refer to DB2 UDB for z/OS Version 8 Installation Guide, GC18-7418. The migration to DB2 V8 is only allowed from V7. As mentioned, a DB2 V8 subsystem will migrate going through three different modes: ► Compatibility mode (CM) ► Enabling-new-function mode (ENFM) ► New-function mode (NFM) We are interested in the performance of the catalog migration, how long the migration will take, and how big the catalog will be. In this section we are using general information from several real migrations to illustrate the catalog migration. After reading this section you will be able to determine how long it is going to take to migrate your catalog and how large it will be after the migration. During the migration process, you must go through CM and ENFM, before reaching the NFM. When in CM, your Catalog and Directory have already successfully been converted to V8, new columns have been added to existing tables, new indexes and table spaces have been created and so on. However, there are two other major changes to the DB2 catalog necessary to make most of the new functions provided with DB2 V8 possible. These changes are: ► Change existing catalog columns so that they can store long names. ► Convert the catalog to Unicode. In CM, these two changes have not been done. Furthermore, the only new functions available for use in this mode of operation are those which allow fallback to V7. In ENFM, you are in the process of converting your Catalog table spaces so that after completion of the conversion, they now accept long names and exist in the Unicode encoding scheme. Catalog conversion is performed by running job DSNTIJNE. You can spread conversion of your catalog table across several maintenance intervals. Use job DSNTIJNH to direct DSNTIJNE to halt after conversion of the current table space has completed. To resume, simply rerun DSNTIJNE from the top. It will automatically locate the next table space to be converted. The process of conversion is not disruptive, that is, you can continue operation while being in ENFM. Once you have migrated all table spaces of your DB2 catalog to Unicode, your DB2 subsystem will operate in NFM once you run the DSNTIJNF to indicate Chapter 9. Installation and migration 353
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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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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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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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Page 336 and 337: The SYSIBM.INDOUBT table and the pa
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Page 340 and 341: Example In DB2 V8 SQL/XML publishin
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Page 344 and 345: 7.5.3 Conclusion The new XML publis
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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
Page 354 and 355: Table 8-1 shows extracts from DB2 P
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Page 366 and 367: Table 8-12 DB2 I/O CI Limit Removal
Page 368 and 369: 8.5 Miscellaneous items In this sec
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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
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Page 380 and 381: From these measurements we observe
Page 382 and 383: Class 1 CPU time (MSEC) 200 150 100
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
Page 426 and 427: B.1 DB2 PE Storage Statistics trace
Page 428 and 429: Storage heading Description 24 BIT
Page 432 and 433: 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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