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

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If explicit clustering for a table is removed (changed to NOT CLUSTER), that index is still used as the implicit clustering index until a new explicit clustering index is chosen. 5.5.4 DPSI and impact on utilities and queries With DB2 V7, secondary indexes on partitioned tables are non-partitioned indexes. Secondary indexes cannot be physically partitioned. They can only be allocated across multiple pieces to reduce I/O contention. DB2 V8 introduces the ability to physically partition secondary indexes. The partitioning scheme introduced is the same as that of the table space. That is, there are as many index partitions in the secondary index as table space partitions, and index keys in partition “n” of the index reference only data in partition “n” of the table space. Such an index is called a Data-Partitioned Secondary Index (DPSI). Description When an index is created and no additional keywords are specified, the index is non-partitioned. If the keyword PARTITIONED is specified, the index is partitioned. The index is both data-partitioned and key-partitioned when it is defined on the partitioning columns of the table. Any index on a partitioned table space that does not meet the definition of a partitioning index is a secondary index. When a secondary index is created and no additional keywords are specified, the secondary index is non-partitioned (NPSI). If the keyword PARTITIONED is specified, the index is a data-partitioned secondary index (DPSI). You create a DPSI by specifying the new PARTITIONED keyword in the CREATE INDEX statement and defining keys on some columns that coincide with the partitioning columns of the table. When defining a DPSI, the index cannot be created as UNIQUE or UNIQUE WHERE NOT NULL. This is to avoid having to search each part of the DPSI to make sure the key is unique. Benefits of DPSIs are: ► Allow partition-level operation for utilities operating on secondary indexes such as REORG INDEX, RUNSTATS INDEX ► Eliminate contention on index pages for utilities operating on partition level with DPSI. ► Utilize concurrent LOAD PART more efficiently while inserting DPSI keys ► Eliminate the BUILD2 phase during Online REORG of a partition ► Reduce data sharing overhead For a detailed description of DPSIs see DB2 UDB for z/OS Version 8: Everything You Ever Wanted to Know, ... and More, SG24-6079. Performance In this section the performance impact of DPSIs on utilities and queries is evaluated. Performance measurement description For this measurement we used: ► z/OS V1R3 ► DB2 for z/OS V8 in NFM ► IBM z900 Series 2064 4-way processor ► ESS model F20 with FICON channels Performance measurement result for utilities and DPSIs We used a partitioned table of 20 M rows with 10 partitions 248 DB2 UDB for z/OS Version 8 Performance Topics
► With one NPI or one DPSI ► With 3 DPSIs and 2 NPIs ► With 5 DPSIs or 5 NPIs The following measurement cases were run: ► Load table ► Reorg table space ► Rebuild index ► Check index ► Runstats index Figure 5-21 shows the result of a measurement where one partition was loaded of a 20 M row table with 10 partitions and 1 NPI vs. 1 DPSI. time in seconds Load a partition of table of 20M rows 10 partitions with 1 NPI and table with 1 DPSI 80 70 60 50 40 30 20 10 0 CPU Elapsed time Table with 1 NPI 62 76 Table with 1 DPSI 28 25 Figure 5-21 Load with 1 NPI vs. 1 DPSI The reduction in CPU of the test case with a DPSI is mostly due to better code method: Load of the DPSI (a page at the time) instead of Insert in the NPI case. In Figure 5-22 we compare the load of a single partition of a 20 M row table with 10 partitions with 5 NPIs or 5 DPSIs versus the load of the whole table. Chapter 5. Availability and capacity enhancements 249
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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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Page 260 and 261: Figure 5-7 shows the sliding scale
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Page 304 and 305: 6.3.2 Conclusion We measured the CP
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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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