CS3223 Tutorial 4. Fan Qi [email protected] Database Lab 1, com1 #01-08. Block I/O Sorting. Key Idea: R/W multi page per I/O Cost: Number of Passes:. 1 block for output. Selection. Access: Table Scan Index Scan Index Seek Index Intersection Index Access: - PowerPoint PPT Presentation
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CS3223 Tutorial 2
Fan Qi [email protected] Lab 1, com1 #01-08CS3223
Tutorial 4Block I/O Sorting 1 block for outputSelectionAccess:Table
ScanIndex ScanIndex SeekIndex Intersection
Index Access:B+ Tree : range and equalityHash : equality
only
CostB+ TreeNavigation costLeaf page scan costRID look up
costHash IndexChain Cost (Reading Bucket Page into Memory)RID look
up costQuestion 1Question
1Disk123203213226406416429609619621280MemoryininininoutQuestion
1Question 1Take-away pointsBlock I/O reduces sorting
timeDiminishing return at some point, why?In practice, read/write
block are of the same sizeSortTime319-Merge640,000,000ms256-Merge,
1 in 64 out344,687,500ms16-Merge, 16 in 64 out126,875,000ms8-Merge,
32 in 64 out135,156,250ms4-Merge,64 in 64 out195,500,000msWhy? As
block size increases, the number of passes slightly increase as
well7Question 31. Table ScanDiskQuestion 3pr250 pagesRid Look up to
get name Question 3pr250 pages500 pagesIntersectDiskRid Look up to
get name Question 3Diskp200 pagesRid Look up to get name for each
record Question 4Question 4Thank you!Happy Recess Week!
