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

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This enhancement is introduced by PTFs UQ90755 (DB2 V7) and UQ90756 (DB2 V8) for APAR PQ87848. IFCID 173 DSECT Example 4-7 shows the DSECT for the new IFCID 173. Example 4-7 IFCID 173 DSECT QW0173 DSECT QW0173ID DS CL8 %U AUTH ID QW0173PC DS CL18 %U PACKAGE COLLECTION ID QW0173PK DS CL8 %U PACKAGE NAME QW0173PL DS CL8 PLAN NAME QW0173CN DS CL18 %U CURSOR NAME if it exists QW0173UT DS F (S) Time used so far QW0173AT DS F (S) User ASUTIME QW0173SN DS H SECTION NUMBER DS CL2 Reserved QW0173ST DS F STATEMENT NUMBER QW0173CS DS XL4 cached statement ID, or zero QW0173DI DS CL128 (S) RLF Diagnostic information area * QW0173ID_Off DS H Offset from QW0173 to * AUTH ID * If QW0173ID truncated QW0173PC_Off DS H Offset from QW0173 to * PACKAGE COLLECTION ID * If QW0173PC truncated QW0173PK_Off DS H Offset from QW0173 to * PACKAGE NAME * If QW0173PK truncated QW0173CN_Off DS H Offset from QW0173 to * CURSOR NAME if it exist * If QW0173CN truncated * QW0173ID_D Dsect Use if QW0173ID_Off^=0 QW0173ID_Len DS H Length of the following field QW0173ID_Var DS 0CL128 %U AUTH ID * QW0173PC_D Dsect Use if QW0173PC_Off^=0 QW0173PC_Len DS H Length of the following field QW0173PC_Var DS 0CL128 %U PACKAGE COLLECTION ID * QW0173PK_D Dsect Use if QW0173PK_Off^=0 QW0173PK_Len DS H Length of the following field QW0173PK_Var DS 0CL128 %U PACKAGE NAME * QW0173CN_D Dsect Use if QW0173CN_Off^=0 QW0173CN_Len DS H Length of the following field QW0173CN_Var DS 0CL128 %U CURSOR NAME if it exist 4.12.6 Performance trace enhancements In this section we discuss enhancements to IFCIDs that are related to DB2 performance trace classes. 210 DB2 UDB for z/OS Version 8 Performance Topics
Full SQL statement text trace record DB2 V8 provides a new IFCID 350, which is both similar and in addition to IFCID 63, which traces the entire SQL statement. Previous versions of DB2 limited the SQL statement text to a maximum of 5,000 bytes (the maximum length of a trace field). Since there is a 5,000 byte limit on a single data item being traced, a “repeating group" of 5,000 byte items are placed in each IFCID 350 record up to a maximum of 6. If that is not enough, multiple IFCID 350 records are produced. IFCID 350 is written under the same circumstances that trigger the writing of IFCID 63. PREPARE attributes are also traced. Enhanced trace recording for PREPARE attribute Since DB2 V7, you can change the attributes of a cursor or SELECT statement on the PREPARE statement. To do so, you use the ATTRIBITES clause on the PREPARE. For example, it allows you to change a cursor’s isolation level by providing a new attribute string. However, in V7 the attribute string is not always present in IFCID records, which makes problem determination and performance analysis more complex. DB2 V8 adds the attribute string to the following trace records: ► IFCID 63: (which contains the first 5,000 bytes of the SQL statement text) now also contains the attribute string on a short prepare. ► IFCID 124: (which is used to obtain information about the currently executing SQL statement through a READS request) now also contains the attributes string. ► IFCID 317: (which is used to retrieve the SQL statement string of a statement in the dynamic statement cache) now also contains the attributes string. Add cached statement ID to IFCID 124 IFCID 124 provides information about the currently executing SQL statement through the READS interface. DB2 V8 enhances IFCID 124 to also include the dynamic cached SQL statement ID. The 4 byte field QW0124ST was added to contain the cached dynamic SQL statement identifier. This enhancement works together with another enhancement in DB2 V8 that allows you to Explain SQL statements from the dynamic statement cache. You can retrieve the information about the currently executing SQL statement via IFCID 124. That now contains the SQL statement ID of the statement in the dynamic statement cache, and then explains the SQL statement from the dynamic statement cache using that statement ID. For more information on how to explain a statement from the dynamic statement cache, see section 4.20, “EXPLAIN STMTCACHE” in the book DB2 UDB for z/OS Version 8: Everything You Ever Wanted to Know, ... and More, SG24-6079. Agent level workfile tracing DB2 V8 introduces a new IFCID 342 to record workfile and TEMP database usage at an application level. This allows you to take corrective action, such as adding space or cancelling a runaway query that is using a lot of space in the databases and preventing other queries from running successfully even they only need very little space. When active, IFCID 342 is written whenever space is allocated or deallocated in the workfile or TEMP database. It gives information about the total amount of space being used by the agent currently and the maximum space that the agent may have used at any given point in time in the workfile or TEMP database. The trace also records the total amount of space being used for indexes on Declared Temporary Tables. Chapter 4. DB2 subsystem performance 211
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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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Page 198 and 199: As you can now appreciate, it is im
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Page 202 and 203: 4.5.1 Performance The most buffer p
Page 204 and 205: 4.6.1 Performance maintained in a 2
Page 206 and 207: 4.6.2 Conclusion We can conclude th
Page 208 and 209: service for Unicode conversions, an
Page 210 and 211: overcome this, when DB2 Connect is
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Page 216 and 217: 4.7.1 Performance The improvements
Page 218 and 219: In October 2003, a new enhancement
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Page 222 and 223: 4.8.1 Performance 4.8.2 Conclusion
Page 224 and 225: Multilevel security with row-level
Page 226 and 227: ► The security level that defines
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Page 230 and 231: 4.9.2 Conclusion The CPU increase c
Page 232 and 233: 4.10.1 Performance VSAM does not kn
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Page 250 and 251: 5.1 System level point-in-time reco
Page 252 and 253: BACKUP SYSTEM During backup DB2 rec
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Page 258 and 259: 5.1.2 Conclusion The BACKUP SYSTEM
Page 260 and 261: Figure 5-7 shows the sliding scale
Page 262 and 263: Maybe you have implemented a space
Page 264 and 265: For dynamically prepared queries, D
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Page 268 and 269: Before ALTER INDEX add column, a ta
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Page 274 and 275: 300 250 200 time in seconds 150 100
Page 276 and 277: REORG REBALANCE We executed and mea
Page 278 and 279: 5.4 Volatile table 5.4.1 Conclusion
Page 280 and 281: If explicit clustering for a table
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Page 286 and 287: RUNSTATS INDEX PARTITION of a DPSI
Page 288 and 289: Note that when the qualified partit
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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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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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DB2 UDB for z/OS Version 8 Performance Topics - IBM Redbooks

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