For each update in the workload which agributes are

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Unformatted text preview: –  Alt (2), (3): data entry size = 10% size of record –  Hash: No overflow buckets. •  80% page occupancy => File size = 1.25 data size –  Tree: 67% occupancy (this is typical). •  Implies file size = 1.5 data size Cost of Opera6ons (a) Scan (b) Equality (c ) Range (d) Insert (1) Heap (2) Sorted (3) Clustered (4) Unclustered Tree index (5) Unclustered Hash index   Several assumptions underlie these (rough) estimates! (e) Delete Cost of Opera6ons (a) Scan (1) Heap (b) Equality (c ) Range (d) Insert BD 0 .5BD BD 2D (e) Delete S earch +D (2) Sorted BD D log 2B D log 2 B + S earch S earch # m atches + BD + BD (3) Clustered 1 .5BD D log F 1 .5B D log F 1 .5B S earch S earch + # m atches + D +D (4) Unclustered B D(R+0.15) D (1 + D log F 0 .15B D (3 + S earch T ree index log F 0 .15B) + # m atches log F 0 .15B) + 2 D (5) Unclustered B D(R+0.1 2 D BD 4D S earch H ash index 25) + 2D   Several assumptions underlie these (rough) estimates! Understanding the Workload •  For each query in the workload: –  –  –  Which rela6ons does it access? Which agributes are retrieved? Which agributes are involved in selec6on/join condi6ons? How selec6ve are these condi6ons likely to be?...
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