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

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that all applications are converted to Unicode, Unicode conversion is supported for every language that is used to access the common database. However, only one nation (code character set) is specified during DB2 installation. This nation's character set is used as the default character set when a database is stored as EBCDIC or ASCII, and is also the default EBCDIC application encoding scheme. This nation will be referred to as the host nation. Minor conversion is only supported for the host nation's EBCDIC encoding scheme. All other nations will use major conversion. How does minor conversion work? The zSeries instruction set has always included a TR instruction that translates one byte for one byte, based on a 256-byte conversion table. A TRT instruction has also existed which could be used to test a string for certain one-byte characters. As long as a single byte Latin alphanumeric character can be represented in UTF-8 by a single byte, a TR instruction will suffice. DB2 V8 has built-in translate tables for most common single byte CCSIDs and if the TRT instruction is “successful”, DB2 V8 can translate the string using a TR instruction. Such translations are called “minor conversions”. The presence of shift-in/shift-out characters in a mixed string will always cause the TRT instruction to fail. If the TRT fails, then DB2 must invoke the z/OS Unicode conversion service. Such conversions in DB2 are called “major conversions”. Whereas minor conversions cannot change the length of the string (in terms of bytes), major conversions may change the length, running the risk of possible truncation or padding when using fixed length columns or host variables. The performance of minor conversion is much better than the performance of major conversion, hence, minor conversion is one of the significant advantages of DB2 V8 compared to V7, and represents an advantage of UTF-8 over UTF-16. Even when DB2 V8 must resort to major conversion, V8 is still much faster than V7. 9.1.3 DB2 catalog changes The DB2 catalog continues to grow with every release of DB2. In addition to the new catalog objects required to support the new functions in DB2 (tables, columns, and so forth), V8 introduces a number of other significant changes to the catalog: ► Changing the definition of many existing columns to support long names ► Converting the character columns in the catalog from EBCDIC to Unicode Refer to the DB2 Release Planning Guide, SC18-7425, and Appendix A of the DB2 SQL Reference, SC18-7426, for a complete list of changes to the DB2 catalog. Table 9-1 shows how the DB2 catalog has grown across its Versions. Table 9-1 DB2 catalog growth DB2 Version Table spaces Tables Indexes Columns Table check constraints V1 11 25 27 269 N/A V3 11 43 44 584 N/A V4 11 46 54 628 0 V5 12 54 62 731 46 V6 15 65 93 987 59 V7 20 82 119 1206 105 V8 22 84 132 1265 105 344 DB2 UDB for z/OS Version 8 Performance Topics
Summary of DB2 Catalog changes The most important changes are: ► Introduction of long names Long names (varchar 128) are supported for most of the objects. Catalogs are defined using Unicode, so if you have existing queries on the catalog, you will receive the results in a different ordering. ► New tables – SYSIBM.IPLIST: Multiple IP addresses to one LOCATION can be defined for data sharing group. – SYSIBM.SYSSEQUENCEAUTH: Created in DSNDB06.SYSSEQ2. It records the privileges that are held by users over sequences. – SYSIBM.SYSOBDS: Created in DSNDB06.SYSALTER, it contains the version of a table space or an index space that is still needed for recovery. ► New table spaces: – SYSEBCDC: EBCDIC table space, not used until NFM SYSIBM.SYSDUMMY1: has been moved from SYSSTR to SYSEBCDC – SYSALTER: New catalog table SYSIBM.SYSOBDS To store prior version information of ALTERed tables – SYSIBM.IPLIST: Created in DSNDB06.SYSDDF Allows multiple IP addresses to be specified for a given LOCATION ► Column changes – Existing binary columns will be ALTERed to be FOR BIT DATA columns to ensure they are handled properly during ENFM processing – Approximately 60 columns added to existing tables – Approximately 15 changes to values of existing columns – Approximately 45 column definitions have been changed – Approximately 10 changes to RI and table check constraints – Column length changes to support long names are only done during ENFM processing In summary, 17 catalog and 1 directory table space have been converted to Unicode, two tables have been dropped (SYSLINKS - No index data sets to be deleted, SYSPROCEDURES - VSAM data sets for Index DSNKCX01 can be deleted after ENFM), the table SYSIBM.SYSDUMMY1 has been moved from DSNDB06.SYSSTR to DSNDB06.SYSEDCBC, many columns have changed to VARCHAR to support long names, system-defined catalog indexes changed to NOT PADDED and 7 catalog and 1 directory table space moved out of BP0. ► Default changes The initial defaults for the - ALTER BUFFERPOOL command have changed: – DWQT: Specifies the buffer pool’s deferred write threshold as a default percentage of the total virtual buffer pool size. The initial default is decreased from 50% to 30%. – VDWQT: Specifies the virtual deferred write threshold for the virtual buffer pool. This parameter accepts two arguments. The first argument is a percentage of the total virtual buffer pool size. The default is decreased from 10% to 5%. The initial defaults for the ALTER GROUPBUFFERPOOL command have changed: Chapter 9. Installation and migration 345
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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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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 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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Page 388 and 389: Table Number of rows SYSDATABASE 75
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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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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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