1. Supporting Complex Multi-dimensional Queries in P2P Systems Bin Liu, Wang-Chien Lee Hong Kong University of Science and Technology ICDCS ‘05 Dik Lun Lee Pennsylvania State University

2. One line comment The system supports multi-dimensional range and kNN queries in P2P network considering peer heterogeneity

3. Motivation Complex Queries for emerging P2P applications  E.g. P2P auction network for real estate - Find available buildings at most 10km from the airport (range) - Select three available buildings closest to the airport (kNN)

4. Problem Existing P2P systems cannot support such complex queries  Can, Chord, Pastry, Tapestry, etc – not for range queries  Mercury, Squid, etc – only for range queries

5. Solution Approach CAN w/o hashing NR-tree indexing Range Query, kNN Query DHT: routing P2P system Queries

6. Solution Approach S1 P1 P2

7. Indexing in a Cluster abcdefghijkE4E5E6E7E8 E1E2 y-axis x-axis P2 E1 E2 E5 E4 E6 E7 E8 a b c d e g h i j k f NR-tree (residing in S1) S1

8. Join (Leave/Failure) abcdefghijkE4E5E6E7E8 E1E2E3 y-axis x-axis P2 E1 E2 E5 E4 E6 E7 E8 a b c d e g h i j k f E3 NR-tree (residing in S1) S1 P3 S1 P2 P3 P4 S2

9. Query Processing – Range query abcdefghijkE4E5E6E7E8 E1E2E3 y-axis x-axis P2 E1 E2 E5 E4 E6 E7 E8 a b c d e g h i j k f E3 NR-tree (residing in S1) S1 P3 query q S1 S3 S2 S4 S5

10. Query Processing – kNN query abcdefghijkE4E5E6E7E8 E1E2E3 y-axis x-axis P2 E1 E2 E5 E4 E6 E7 E8 a b c d e g h i j k f E3 NR-tree (residing in S1) S1 P3 query q S1 S3 S2 S4 S5 E2E1E3

11. Analysis of the system Routing cost Dynamic load balancing is difficult Join 할 때 한 peer 가 관리하는 data 에 locality 가 있다는 가 정이 현실성 부족 Not efficient kNN query support Query result correctness 를 100% 보장 못함 Node heterogeneity 를 고려했지만 어떠한 보장도 못함

12. Experiment Parameters 10000 1000 100 clusters 12 nodes

13. Experiment – cost vs. distribution per query per node join/leave

14. Experiment – cost vs. query size

15. Experiment – cost vs. cluster size

16. Experiment – TTL

17. Experiment - # of backup super-peers