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Cloud Database Final Project
- 1. Cache-Efficient Aggregation: Hash Is Sort SIGMOD 2015 Team 3 曾振瑋 曾若淳
- 2. Group Aggregation ● SELECT COUNT(student_id) FROM cloudDB GROUP BY team_id --------------------------------- 2 2 2 2 2 2 2 2 2 3 Actual #rec = 10
- 3. Group Aggregation ● 2 Algorithms – Sort-based Aggregation (Vanilladb) – Hash-based Aggregation (ours)
- 4. Sort-based Aggregation 1. sort all records by group attributes Input records
- 5. Sort-based Aggregation Input records split into runs 1. sort all records by group attributes
- 6. Sort-based Aggregation Input records split into runs sorted sorted sorted sorted sort individually 1. sort all records by group attributes
- 7. Sort-based Aggregation Input records split into runs sorted sorted sorted sorted sort individually merge all runs sorted 1. sort all records by group attributes
- 8. Sort-based Aggregation 2. aggregate consecutive records Input records split into runs sorted sorted sorted sorted sort individually merge all runs sorted result aggregate 1. sort all records by group attributes
- 10. Hash-based Aggregation buckets hash function records key = group attributes use group attribute as key 00 01 02 03 04 05
- 11. Hash-based Aggregation insert into corresponding bucket hash function key = group attributes records buckets 00 01 02 03 04 05
- 12. Hash-based Aggregation buckets hash function records key = group attributes aggregate inside bucket 00 01 02 03 04 05
- 13. Hash-based Aggregation buckets hash function records key = group attributes If small #group, large #record 00 01 02 03 04 05 ... => better than Sort-based
- 14. Hash-based Aggregation What if hashtable grows too large? records key = group attributes ... hash function buckets 00 01 02 03 99 ... cache miss! cache miss!
- 17. HashIsSort Aggregation hash function key = group attributes run1 split records like Sort-based ... buckets 00 01 02 03 99 ... run2 buckets 00 01 02 03 99 ... hash function
- 18. HashIsSort Aggregation and merge all hashtables buckets 00 01 02 03 99 buckets 00 01 02 03 99 ... + result ...
- 19. HashIsSort Aggregation Input records split into runs
- 20. HashIsSort Aggregation Input records split into runs Insert and aggregate individually aggregated aggregated aggregated aggregated
- 21. HashIsSort Aggregation Input records split into runs aggregated aggregated aggregated aggregated Insert and aggregate individually merge all aggregated values aggregated
- 23. Experiment ● Environment: Macbook – CPU: 2.6GHz Intel i5 – Memory: 8GB 1600MHz DDR3 – Disk: 256G SSD ● Group Aggregation on 8100 record – #group=10,810,1400,5500,8100
- 24. Experiment