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

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D.1.3 DSN_FUNCTION_TABLE You can use DB2 EXPLAIN to obtain information about how DB2 resolves functions. DB2 stores the information in a table called DSN_FUNCTION_TABLE. DB2 inserts a row in DSN_FUNCTION_TABLE for each function that is referenced in an SQL statement when one of the following events occurs: ► You execute the SQL EXPLAIN statement on an SQL statement that contains user-defined function invocations ► You run a program whose plan is bound with EXPLAIN(YES), and the program executes an SQL statement that contains user-defined function invocations Before you use EXPLAIN to obtain information about function resolution, you need to create the DSN_FUNCTION_TABLE. The contents are listed in Table D-4. Table D-4 DSN_FUNCTION_TABLE extensions Column Type Content QUERYNO INTEGER A number that identifies the statement being explained. QBLOCKNO INTEGER A number that identifies each query block within a query. APPLNAME VARCHAR (128) The name of the application plan for the row. PROGNAME VARCHAR (128) The name of the program or package containing the statement being explained. COLLID CHAR (8) The collection ID for the package. GROUP_MEMBER CHAR (8) The member name of the DB2 that executed EXPLAIN, or blank. EXPLAIN_TIME TMESTAMP Timestamp when the EXPLAIN statement was executed. SCHEMA_NAME VARCHAR(128) NOT NULL WITH DEFAULT FUNCTION_NAME VARCHAR(128) NOT NULL WITH DEFAULT SPEC_FUNC_NAME VARCHAR(128) NOT NULL WITH DEFAULT 416 DB2 UDB for z/OS Version 8 Performance Topics Schema name of the function that is invoked in the explained statement. Name of the function that is invoked in the explained statement. Specific name of the function that is invoked in the explained statement. FUNCTION_TYPE CHAR(2) NOT NULL WITH DEFAULT The type of function that is invoked in the explained statement. Possible values are: SU - Scalar function, TU - Table function VIEW_CREATOR VARCHAR(128) NOT NULL WITH DEFAULT The creator of the view, if the function that is specified in the FUNCTION_NAME column is referenced in a view definition. Otherwise, this field is blank.
Column Type Content VIEW_NAME VARCHAR(128) NOT NULL WITH DEFAULT PATH VARCHAR(2048) NOT NULL WITH DEFAULT FUNCTION_TEXT VARCHAR(1500) NOT NULL WITH DEFAULT D.1.4 DSN_STATEMNT_CACHE_TABLE This new table was recently introduced by PTF UQ89372 for APAR PQ88073. With this enhancement a new keyword ALL is added to EXPLAIN STMTCACHE and a new explain table DSN_STATEMENT_CACHE_TABLE is created to hold the output of IFCID 316 and IFCID 318. A brief description follows, as reported in the APAR text. There are two different sets of information that can be collected from the SQL statements in the dynamic statement cache. Specifying STMTCACHE with the STMTID or STMTTOKEN keywords causes the traditional access path information to be written to the PLAN_TABLE for the associated SQL statement as well as a single row written to DSN_STATEMENT_CACHE_TABLE if it exists. However, specifying STMTCACHE with the new ALL keyword causes information to be written to only DSN_STATEMENT_CACHE_TABLE. It consists of one row per SQL statement in the dynamic statement cache for which the current authorization ID is authorized to execute. The contents of these rows show identifying information about the cache entries, as well as an accumulation of statistics reflecting the executions of the statements by all processes that have executed the statement. This information is nearly identical to the information returned from the IFI monitor READS API for IFCIDs 0316 and 0317. Note that the collection and reset of the statistics in these records is controlled by starting and stopping IFCID 318. For more details, see "Controlling collection of dynamic statement cache statistics with IFCID 0318" in DB2 UDB for z/OS Version 8 Administration Guide, SC18-7413-01, Appendix E - Programming for the Instrumentation Facility Interface (IFI). The new EXPLAIN option is: EXPLAIN STMTCACHE ALL; The name of the view, if the function that is specified in the FUNCTION_NAME column is referenced in a view definition. Otherwise, this field is blank. The value of the SQL path when DB2 resolved the function reference. The text of the function reference (the function name and parameters). SQLCODE -20248 is issued if no statement is found in the cache for the auth ID that is used. -20248 ATTEMPTED TO EXPLAIN A CACHED STATEMENT WITH STMTID, STMTTOKEN ID-token, OR ALL BUT THE REQUIRED EXPLAIN INFORMATION IS NOT ACCESSIBLE. Before you can use EXPLAIN STMTCACHE ALL, Statement Cache must be turned on. You must also create the table DSN_STATEMENT_CACHE_TABLE to hold the results of EXPLAIN STMTCACHE ALL. The DDL is shown in Example D-1. Appendix D. EXPLAIN and its tables 417
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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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--------------------------- -------
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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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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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Page 408 and 409: DSNTIAUL with multi-row fetch The r
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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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
Page 434 and 435: |is the last matching predicate. Ap
Page 436 and 437: |ANL6052I *** NOTE: | |This index i
Page 438 and 439: PREDICATE ANALYSIS ----------------
Page 440 and 441: D.1 DB2 EXPLAIN EXPLAIN describes t
Page 442 and 443: Table D-2 PLAN_TABLE contents and b
Page 444 and 445: Column Type Content SORTC_ORDER BY
Page 446 and 447: Column Type Content OPTHINT CHAR(8)
Page 450 and 451: Example: D-1 Creating DSN_STATEMENT
Page 452 and 453: Column Type Content BIND_QUALIFIER
Page 456 and 457: ICF integrated catalog facility ICF
Page 458 and 459: ► DB2 UDB for z/OS V8: Through th
Page 462 and 463: character set 174 CHECK DATA 262 CH
Page 464 and 465: Equi-join predicates 54, 402 Equiva
Page 466 and 467: MINSTOR 145-146 Mismatched data typ
Page 468 and 469: PQ84160 378, 387 PQ85764 387 PQ8584
Page 470 and 471: Sort tree nodes 144 SORTDATA 268 SO
Page 472 and 473: 306 Universal Driver for SQLJ and J
Page 476: DB2 UDB for z/OS Version 8 Performa
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