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انتخاب دید ذخیره شده در پایگاه داده های تحلیلی. ارائه دهندگان : محمد رضا شمس محمد تقی صفار استاد مربوطه: دکتر رهگذر پاییز 88. رئوس مطالب. معرفی پایگاه داده تحلیلی ( Data Warehousing ) معرفی جداول بعد و واقعیت دید ذخیره شده ( Materialized View ) محاسبه هزینه دید ذخیره شده - PowerPoint PPT Presentation

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PowerPoint Template

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2 (Data Warehousing) (Materialized View)

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3 Bill Inmon: : (OLAP) 4

4 : : : : : (Cube)(Dimension) (Fact)

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5 6 :

6 : : : : : !!!

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7 (constraint) (query) Linear cost model

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8Query DAG DAG: Directed acyclic graph DAG9

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10 Q=(Q1,Q2, ,Qm) S=(S1, S2 , ,Sn)query DAG :GQi G: (multi query graph)

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11 Q=(Q1,Q2, ,Qm) S=(S1, S2 , ,Sn):GSi DAG

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: Total cost(v)=E(G(v)) + M(G(v)) M :

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NP- Complete

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ALL . GROUP-BY SQL.

: : . : (supplier1, part1, customer1) = 50(supplier1, ALL, customer1) = 7514

( _ , ALL, _ ) . ALL GROUP-BY .

GROUP-BY .

. ( )

(materialized view selection)15

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GROUP-BY .

: A B A B A B iff A is a subset of B

:{supplier} {supplier, part}16

= LUB GLB . lattice diagram .{p, s, c}

{p, c} {s, c} {p, s}

{c} {s} {p}

none17

.

.

: .

{time} 3 {day}, {month} {year} .

{month} {day} {year} {month} {day} .{year} {month} {day}18

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:

none19

{supplier} {supplier, part} {year} {month}

.N .(a1, a2, , an) (b1, b2, , bn) if for all i ai bi20

. . .

: . : . .21

K .

.C(x) x.

v u C(u) : u .v u. 22

: S . B(v, S) v S : w v Bw : u S w u C(v) C(u) Bw = C(u) C(v) . B(v, S) = Bw v B(v, S) K 23

S = {top view}for i = 1 to k do beginselect that view v not in S such that B(v, S) is maximizedS = S union {v}end;resulting S is the greedy selection24

: 4 .

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. .

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: . . .

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: Bw Bw .

: B(v, S) / C(v) . . .29

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C.A. Dothe, M.S. Ali, Materialized View Selection in Data Warehousing: A Survey, Journal of Applied Sciences 9 (3): 401 414, 2009.V. Harinayaran, A. Rajaraman, J.D. Ullman, Implementing Data Cubes Effieciently, ACM SIGMOD Record, 25: 205 216, 1996.B. Ashadevi, R. Balasubramanian, Cost Effective Approach for Materialized Views Selection in Data Warehousing Environment, IJCSNS 8 (10): 236 242, 2008.B. Inmon, Data Warehousing Fundamentals, John Wiley & Sons, Inc., 200131

Thank You !

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