External Sorting KDD Laboratory外部排序 KDD实验室.ppt

Database Management Systems, R. Ramakrishnan and J. Gehrke
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Database Management Systems, R. Ramakrishnan and J. Gehrke
Heap-Sort Procedure
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4Βιβλιοθήκη Baidu
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What are the differences and the similarities
between these two heap trees?
Database Management Systems, R. Ramakrishnan and J. Gehrke
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2. Heapsort Procedure
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In-Memory Sorting: Heap-Sorting
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How?
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Database Management Systems, R. Ramakrishnan and J. Gehrke
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In Memory Sorting: Heap-Sorting
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External Sorting
Chapter 13
Database Management Systems, R. Ramakrishnan and J. Gehrke
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Why Sort?
A classic problem in computer science! Data requested in sorted order
External Sorting: When the size of file to be sorted is bigger than that of available memory!
Database Management Systems, R. Ramakrishnan and J. Gehrke
– e.g., find students in increasing gpa order – Nearest neighbor search also needs sorting!
Sorting is the first step in bulk loading B+ tree index. Sorting useful for eliminating duplicate copies in a collection of records (Why?) Sort-merge join algorithm involves sorting.
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In-Memory Sorting: Heap-Sorting
Original Data Page
4 1 3 2 16 9 10 14 8 7
Sorted
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Data Page
How can we obtain the sorted data page?
1. Build-Heap Procedure
Database Management Systems, R. Ramakrishnan and J. Gehrke
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Sorting Types
In-Memory Sorting: When the size of memory is bigger than that of file to be sorted!
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