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

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Impact on coupling facility: You do not need to resize the group buffer pools, lock structure or SCA in the coupling facility as a result of moving to DB2 V8, even though the virtual buffer pools have now moved above the bar and have a longer memory address. Improved LPL recovery: Currently LPL recovery requires exclusive access to the table space. DB2 V8 introduces a new serialization mechanism whereby LPL recovery is much less disruptive. In addition, DB2 V8 automatically attempts to recover LPL pages as they go into LPL, when it determines the recovery will probably succeed. Instrumentation has also improved whereby DB2 now attempts to indicate the reason pages are added to the LPL. Restart LIGHT enhancements: If indoubt units of recovery (UR) exist at the end of restart recovery, DB2 will now remain running so that the indoubt URs can be resolved. After all the indoubt URs have been resolved, the DB2 member that is running in LIGHT(YES) mode will shut down and can be restarted normally. Change to close processing for pseudo close: Table spaces defined as CLOSE NO are still closed during pseudo close processing at the end of the PCLOSET interval. This caused degraded performance because the data sets must be physically opened again on the next access. DB2 V8 now really honors the CLOSE NO attribute during pseudo close processing. See PTF UQ74866 for APAR PQ69741 for DB2 V7. Buffer pool long term page fix: DB2 V8 allows you to fix the buffer pool pages once in memory and keep them fixed in real storage. This avoids the processing time that DB2 needs to fix and free pages each time there is an I/O. Batched index page splits: Prior to V8, index page splits for indexes with inter-DB2 read/write interest required multiple synchronous log writes and multiple separate writes to the group buffer pool. This was required to ensure the integrity of the index for other DB2 members during the actual page split. DB2 V8 is able to accumulate the index page split updates and process them as a single entity, thereby reducing log writes and coupling facility traffic. 320 DB2 UDB for z/OS Version 8 Performance Topics
8.1 CF request batching 8.1.1 Performance z/OS 1.4 and CF Level 12 bring two new coupling facility “commands”, Write And Register Multiple (WARM) and Read For Castout Multiple (RFCOM). DB2 V8 data sharing will use these new coupling facility commands, if available, to reduce the amount of traffic to and from the coupling facility for writes to group buffer pools and reads for castout processing, thus reducing the data sharing overhead for insert, update and delete-intensive workloads. When the group buffer pool is allocated in a coupling facility with CFLEVEL= 12 or higher, DB2 can register a list of pages that are being prefetched with one request to the coupling facility. This can be used for sequential prefetch (including sequential detection) and list prefetch. For those pages that are cached as “changed” in the group buffer pool, or those that are locked for castout, DB2 still retrieves the changed page from the group buffer pool one at a time. For pages that are cached as “clean” in the group buffer pool, DB2 can get the pages from the group buffer pool (one page at a time), or can include the pages in the DASD read I/O request, depending on which is most efficient. z/OS 1.4 and CF level 12 introduce two new CF “commands” to: ► Write And Register Multiple (WARM) pages to a group buffer pool with a single command. ► Read multiple pages from a group buffer pool for castout processing with a single CF read request. The actual command is called Read For Castout Multiple (RFCOM). CF level 13 also introduces performance improvements related to DB2 castout processing. See the Web page: http://www.ibm.com/servers/eserver/zseries/pso/coupling.html DB2 V8 uses the CF request batching commands to read and write pages to and from the group buffer pool if more than one page needs to be read or written. DB2 instrumentation (statistics IFCID 2 and accounting 3 and 148) records are enhanced to reflect the usage of these new commands. The DB2 PE accounting and statistics reports are enhanced to externalize the new counters that indicate the number of WARM and RFCOM requests in the GBP section: ► WRITE AND REGISTER MULTI The number of Write and Register Multiple (WARM) requests. ► PAGES WRITE & REG MULTI The number of pages written using Write and Register Multiple (WARM) requests. ► READ FOR CASTOUT MULTI The number of Read For Castout Multiple (RFCOM) requests. A number of performance studies have been done to understand the impact of using CF request batching. For these studies, a two member data sharing group was used, running the IRWW workload. z/OS 1.3 was compared to z/OS 1.4, to isolate the impact of CF request batching. CF request batching is not available in z/OS 1.3. Chapter 8. Data sharing enhancements 321
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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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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 330 and 331: DB2 Universal Type 4 Driver - JDBC
Page 332 and 333: Use DB2 Connect when a high amount
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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 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
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
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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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