Optimizing SQL Insert Performance - GSE Belux

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Distributed Free Space … • For best insert performance – Random key insert to index • Use non-zero index PCTFREE and/or FREEPAGE To reduce index leaf page splits For efficient sequential index read – Sequential key insert to index • Immediately after LOAD, REORG, or CREATE/RECOVER/REBUILD INDEX Use PCTFREE 0 to reduce the number of index pages and possibly index levels by populating each leaf page 100% – Use PCTFREE=FREEPAGE=0 for data to reduce both sync read and async write I/Os for each row insert • Possible performance penalty for query in terms of sync single page I/O when reading multiple rows via clustering index 16 © 2010 IBM Corporation
TRACKMOD NO • Reduces spacemap contention in data sharing environment • DB2 does not track changed pages in the spacemap pages • It uses the LRSN value in each page to determine whether a page has been changed since last copy • Trade-off as degraded performance for incremental image copy because of tablespace scan 17 © 2010 IBM Corporation
Page 1 and 2: DB2 for z/OS Optimizing Insert Perf
Page 3 and 4: Agenda • Insert Space Search •
Page 5 and 6: Choice: Performance or Space Reuse
Page 7 and 8: Space Search Steps (Classic Partiti
Page 9 and 10: PBG search algorithm for entire tab
Page 11 and 12: Segmented Tablespace • Segmented
Page 13 and 14: Partitioned Tablespace • Use page
Page 15: Distributed Free Space • Use dist
Page 19 and 20: MEMBER CLUSTER … • Rows inserte
Page 21 and 22: MEMBER CLUSTER, PCTFREE = 0 and FRE
Page 23 and 24: Typical Performance Bottlenecks and
Page 25 and 26: Read and Write I/O for Index and Da
Page 27 and 28: Read and Write I/O for Index and Da
Page 29 and 30: Lock/Latch and Service Task Waits
Page 31 and 32: DB2 Latch Contention • Latch Coun
Page 33 and 34: GENERATE_UNIQUE() • Built-in func
Page 35 and 36: DB2 9 Performance Enhancements 35
Page 37 and 38: Large Index Page Size • Available
Page 39 and 40: Increased Index Look Aside • Prio
Page 41 and 42: Randomised Index Key • Index cont
Page 43 and 44: Identifying Unreferenced Indexes
Page 45 and 46: DB2 10 Performance Enhancements 45
Page 47 and 48: V10 Enhancements ... • In-line LO
Page 49 and 50: Summary - Key Points • Decide whe

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