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Routing Indices For Peer-to-Peer Systems. Arturo Crespo, Hector Garcia-Molina Stanford ICDCS 2002. Motivation and ideas. Search (text) documents with specific keyword (category) in P2P network content-based Users only interested in TOP 20 results Each peer stores statistics of - PowerPoint PPT Presentation
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Routing Indices For Peer-to-Peer Systems
Arturo Crespo, Hector Garcia-Molina
StanfordICDCS 2002
Motivation and ideas
Search (text) documents with specific keyword (category) in P2P network content-based
Users only interested in TOP 20 results
Each peer stores statistics of Documents shared by itself Documents shared by its neighbors
Route query to a “good” peer
Sequential search vs parallel search
Proposed Methods
Compound RI - naive
Hop-count RI - improved
Exponential RI - best
What is routing indices?
For A, there are 100 documents available from B (and its descendents)
20 belong to Database category 10 belong to Theory category 30 belong to Languages category
“Goodness” of a neighbor
i
isCRI
Documents OfNumber
)(Documents OfNumber
Computing goodness
For documents of “databases” and “languages”
75200
150
200
100200)(
0100
50
1000
01000)(
6100
30
100
20100)(
DGoodness
CGoodness
BGoodness
Updating of routing indices
New connection
RI propagation D+A+J
D+A+I
Proposed Methods
Compound RI – naive
Hop-count RI – improved
Exponential RI - best
Problems and improvements
Improved cost model take into account of query messages generated
Less update cost RI propagates through limited hops (horizon)
Robust against cycles
300 items
250 items
Hop-count RI
For W, it can reach 30 documents from Y 1 hop away
Y has 30 documents 50 documents from Y 2 hops away
Y1,Y2 have 50 documents
Goodness measure in Hop-count RI
Goodness of
hj ji
h F
QjNgoodnessQNiGoodness
..0
)],[(),(
33.53
102
33.103
310
33.163
1013
Z
Y
X
Proposed Methods
Compound RI – naive
Hop-count RI – improved
Exponential RI - best
Improvements
Hop-count RI exhibits High storage cost High update cost of RI
Compress RI of different Hops together
Similar to Compound RI with RI update method differs
RI Update
I changed to 70, 30, 10, 20, 50
RI Update
D update I’s row as 70, 30, 10, 20, 50
70 30 10 20 50
RI Update
D sent J’s update as 590, 86.67, 130, 70, 121.67
70 30 10 20 50
RI Update
70 30 10 20 50
590 86.67 130 70 121.67
D send A and update as 140, 75, 3.3, 75, 100
Experiment
Query Message generated
Why CRI, HRI, ERI perform much better in the uniform distribution?
Effect of index compression
Effect of cycles
Query message in different network topology
Update cost in different network topology
END
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