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

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4.8.1 Performance 4.8.2 Conclusion The following software is required to support clear keys ► APAR PQ93943 and PQ94822 for the tool ► ICSF SPE APAR OA08172 (availability TBD) ► FMID HCR770A or HCR770B ► OS/390 V2R10 or later The following hardware is also required to support “clear” keys ► On z990, both CPACF and a PCIXCC card ► Pre z990, cryptographic coprocessor While, secure keys require the following hardware: ► On z990, a PCIXCC card ► Pre z990, the cryptographic coprocessor The PCIXCC card is required to install ICSF, which in turn, manages the encryption keys. Studies on z990 have shown DB2 encryption costs approximately 2.3 microseconds per column, plus 0.0086 microseconds per byte. While the Encryption Tool (clear key) costs roughly 1 microsecond per row, plus 0.006 microseconds per byte. So, to fetch 100k rows, encrypting two 32 byte columns using DB2 encryption: DB2 cost of encryption = 2x(2.3 + 32x0.0086)x100,000 = 520,000 microseconds To fetch 100k rows with row size of 204 bytes using the Encryption Tool, the additional CPU time is: Encryption Tool cost = (1+204x0.006)x100,000 = 220,000 microseconds For an equivalent number of bytes, we found it is faster to use DB2 encryption to encrypt and decrypt the data, in situations where the number of columns to be encrypted is three or less. Otherwise, may be a better choice. The breakeven point varies depending on how many other columns are in the table and how big each column is, but generally the IBM Data Encryption Tool is a better choice than DB2 column level encryption from the performance level point of view. The cost of encryption is reduced on the z990 hardware, compared with the older z900 hardware. CPU time for the Encryption Tool is 10 times faster on a z990 versus the z900, and the elapsed time for multithreaded applications using encryption is much faster on z990 versus z900 depending on the number of concurrent tasks. Similar observations are applicable to the z890 processor, which has the same level of relative performance as the z990. The CPU performance implications for encryption are similar to data compression. However the impact on encryption on CPU is likely to be slightly higher than compression. OLTP performance is less affected than query performance. The best query performance is achieved by designing good indexes to avoid “touching” many rows. 190 DB2 UDB for z/OS Version 8 Performance Topics
4.8.3 Recommendations For both DB2 encryption and the IBM Data Encryption Tool, we recommend you move to the current z990 or z890 hardware, where the hardware-assisted encryption instructions are available on all processors. The IBM Encryption Tool (row level) performs generally better than the DB2 encryption and decryption (column level). The break even point varies depending on how many other columns are in the table and their size. However, performance is not the only reason to choose one encryption strategy over the other, as they also vary in function. Encryption is done before compression, so compression and encryption cannot be effectively combined. Encrypted data does not tend to compress very well because repeating unencrypted characters are no longer repeating after they are encrypted. Important: Be aware that if you plan to use DRDA encryption, you need the PCIXCC function on your z990, because the hardware requires it. 4.9 Row level security DB2 recognized the need for more granular security of DB2 data and introduced support for Row Level Security in V8. Multilevel security support in z/OS 1.5 and RACF Security Server 1.5, in conjunction with DB2 V8, simplify row level security implementation and management significantly. In this section we first introduce Row Level Security, then describe the performance impact of Row Level security on DB2 workloads. Security is becoming increasingly important in the past few years. Row level access control is increasingly critical. Many customers need to extend the granularity from table level to row level, so that an individual user is restricted to a specific set of rows. Good examples are Web hosting companies that need to store data from multiple customers into a single subsystem, database or table. In the past, views have been used to hide data. They can subselect data to provide only certain columns or fields. By creating a view and granting privileges on it, you can give someone access to only a specific combination of data. However, the application tends to become much more complex when views are used in this way. Separating the data into different databases or base tables has also been used to provide more granular security. DB2 recognizes this need and introduces support for Row Level Security in V8. Multilevel security (MLS) support in z/OS 1.5 and RACF Security Server 1.5, in conjunction with DB2 V8, simplify row level security implementation and management significantly. Multilevel security is a security policy that allows the classification of data and users based on a system of hierarchical security levels, combined with a system of non-hierarchical security categories. A multilevel-secure security policy prevents unauthorized individuals from accessing information at a higher classification than their authorization (read-up), and prevents individuals from declassifying information (write-down). You can use MLS for multiple purposes in DB2: Chapter 4. DB2 subsystem performance 191
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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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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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- 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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