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DB Performance: Set Query Comparison Both indexed retrieval of individual rows and sequential scan have sped up since DB2 MVS, but sequential scan much more! Sequential scan speed has increased from MVS to UDB by a factor of 88; random row retrieval speed by a factor of 4 FFs for speeding up random row retrieval are less important, but clustering is more important: reduces sequential scan range KN Used In Q3B Rows Read (of 1M) DB2 MVS Index usage DB2 UDB Index usage DB2 MVS Time secs K100K 1 K100 K100 1.4 0.7 K10K 6 K10K K10K 2.4 3.1 K100 597 K100, KSEQ KSEQ 14.9 2.1 K25 2423 K25, KSEQ KSEQ 20.8 2.4 K10 5959 K10, KSEQ KSEQ 31.4 2.3 K5 12011 KSEQ KSEQ 49.1 2.1 DB2 UDB Time secs 24
Disk Performance Our “disktest” program generates read requests to a 20 GB file, as a database would Sits on 4-disk RAID system of enterprise disks (15K RPM) Various read request sizes: rsize = 4KB, 16KB, 64KB, 256KB From 1 to 300 read requests outstanding Either read whole file in order in rsize reads, or only some of it: “skip-sequential” reads We use random numbers to determine successive rsize blocks to read, with probability p, p = 1.0, 0.1, 0.01, 0.001 Case of p = 1.0 specifies sequential reading, like a table scan Case of p < 1.0 specifies skip-sequential, like index-driven database access: ordered RIDs access rows left-to-right on disk DB2 orders RIDs before accessing, ORACLE seems not to 25
Page 1 and 2: EDBT Summer School Database Perform
Page 3 and 4: DB Performance: OLTP Jim Gray said
Page 5 and 6: OLTP DebitCredit Benchmark D
Page 7 and 8: DB Performance: OLTP & Queries
Page 9 and 10: DB Performance: Snapshot Isolation
Page 15 and 16: DB Performance: Queries Companies
Page 17 and 18: DB Performance: Set Query Benchmark
Page 19 and 20: DB Performance: Set Query Benchmark
Page 21 and 22: Set Query Benchmark KNK index examp
Page 23: DB Performance: Set Query Compariso
Page 27 and 28: Sequential Scan Performance E
Page 29 and 30: DB Performance:Outline of What Foll
Page 31 and 32: Multi-Dimensional Clustering Cluste
Page 33 and 34: DB Performance: Multi-Dim Clusterin
Page 35 and 36: DB Performance: Star Schema (SS)
Page 37 and 38: DB Performance: Data Warehousing D
Page 39 and 40: DB Performance: Multi-Dim Clusterin
Page 41 and 42: ADC: Outline of What Follows ADC w
Page 44 and 45: Considerations and Futures of ADC
Page 46 and 47: Using ADC With Oracle Oracle has a
Page 48 and 49: Star Schema Benchmark (SSB) Recall
Page 50 and 51: SSB is Derived From TPC-H Benchmark
Page 52 and 53: Why Changes to TPC-H Make Sense To
Page 54 and 55: Star Schema Benchmark Queries Succ
Page 56 and 57: SSB Test Specifications We measure
Page 58 and 59: DB Products A, B & C Times in Secon
Page 60 and 61: Analysis of SSB and Conclusions Que
Page 62 and 63: Analysis and Conclusions Reader
Page 64: Bibliography P.G. Selinger et al.,

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