Front cover IBM Db2 12 for z/OS Performance Topics Akiko Hoshikawa Mai Nguyen Bart Steegmans Neena Cherian Bharat Verma Nguyen Dao Brian Baggett Ou Jin Chang Kim Peng Huang Chongchen Xu Ping Liang Chung Wu Robert Boon Cristian Molaro Todd Munk Jasmi Thekveli Xue Lian Zhang Kaitlin E. Murray Liang Zhang Lingyun Wang Redbooks International Technical Support Organization IBM Db2 12 for z/OS Performance Topics September 2017 SG24-8404-00 Note: Before using this information and the product it supports, read the information in “Notices” on page ix. First Edition (September 2017) © Copyright International Business Machines Corporation 2017. All rights reserved. Note to U.S. Government Users Restricted Rights -- Use, duplication or disclosure restricted by GSA ADP Schedule Contract with IBM Corp. Contents Notices . ix Trademarks . .x Preface . xi Authors. xi Now you can become a published author, too! . xiii Comments welcome. xiii Stay connected to IBM Redbooks . xiv Chapter 1. Introduction . 1 1.1 Overview . 2 1.1.1 Performance . 2 1.1.2 High-level expectations . 4 1.2 Db2 12 for z/OS performance features . 6 1.2.1 System-level performance . 6 1.2.2 Query performance improvement . 16 1.2.3 Access path stability for dynamic SQL statements . 17 1.3 Other key features in Db2 12 for z/OS . 18 1.3.1 Mobile application enablement . 18 1.3.2 Resiliency and continuous availability. 19 1.3.3 Simplified migration and continuous delivery support . 20 1.4 How to use this book . 21 1.4.1 Measurement environments . 22 Chapter 2. Scalability enhancements and subsystem performance . 23 2.1 Fast index traversal. 24 2.1.1 Introduction . 24 2.1.2 Performance measurements. 26 2.2 Contiguous buffer pools . 39 2.2.1 Introduction . 39 2.2.2 Performance measurements . 41 2.2.3 Managing a contiguous buffer pool. 42 2.2.4 Usage considerations for contiguous buffer pools . 48 2.3 Insert Algorithm 2 . 50 2.3.1 Insert Algorithm 2 overview. 50 2.3.2 How Insert Algorithm 2 works . 52 2.3.3 Performance measurements. 53 2.3.4 Insert Algorithm 2 usage considerations. 56 2.4 Logging enhancements. 57 2.4.1 Greater than 4 GB active log support . 57 2.4.2 Removing log write latch (LC19). 60 2.4.3 Forced log write removal for identity columns. 61 2.5 Range-partitioned table spaces with relative page numbering . 63 2.5.1 Performance measurements . 64 2.6 IMS-Db2 Connection pooling . 65 2.6.1 Performance measurements. 67 2.6.2 Usage considerations . 67 2.7 Db2 prefetch-related enhancements. 68 2.7.1 Increased numbers of Db2 prefetch engines . 68 © Copyright IBM Corp. 2017. All rights reserved. iii 2.7.2 Avoiding unnecessary dynamic prefetch scheduling . 69 2.8 Performance enhancements for short transactions . 71 2.8.1 DGTT enhancements . 71 2.8.2 Claim and declaim performance improvements . 73 2.8.3 SELECT INTO optimization . 75 2.9 Db2 Storage Manager enhancements . 76 2.9.1 Scalability and performance improvement for EDM pools . 76 2.9.2 Storage pool management improvement for XML and LOBs . 81 2.10 Miscellaneous enhancements. 81 2.10.1 zPLX 3.2.0 Performance enhancement . 81 2.10.2 Latch class 23 reduction . 82 Chapter 3. Synergy with the IBM Z platform. 83 3.1 Large object compression . 84 3.1.1 LOB compression prerequisites . 84 3.1.2 LOB compression considerations . 85 3.1.3 Use of DSN1COMP to estimate LOB compression . 86 3.1.4 Performance characteristics of LOB compression . 89 3.2 ISM that uses SMC-D . 93 3.2.1 HiperSockets, SMC-R, and SMC-D . 93 3.2.2 Request/response workload performance summary comparison of HiperSockets and OSA with and without SMC-D. 95 3.2.3 SMC-D results for IRWW SQLJ OLTP workload . 98 3.3 Simultaneous multithreading. 100 3.3.1 SMT-2 Performance in a one-way data sharing environment . 102 3.3.2 SMT-2 performance in a two-way data sharing environment . 105 3.4 Performance effect of the use of 2 GB frames . 107 3.4.1 Performance measurements. 107 3.4.2 Usage guidance and considerations. 108 3.5 Buffer pool simulation . 110 3.5.1 Performing buffer pool simulation . 110 3.5.2 Performance measurement results . 113 3.5.3 Buffer pool simulation usage considerations. 114 3.6 Large group buffer pool usage . 115 3.6.1 Performance measurements. ..