Appendix C

1. Appendix C File Organization & Storage Structure

2. Agenda • Definition • Types of File Organization

3. Definition • Logical record & physical record • File organization • Access method

4. Types of File Organization • Heap (unordered) • Sequential (ordered or sorted) • Hash (direct or random) • Index

5. Heap • Unordered structure • Pros • Simple • No overhead • Cons • Slow • Waste space (deletion) • For • Bulk-loaded • Short file • Retrieving 80% of the file

6. Ordered • Sorted according to a field value or primary key field • Pros • Binary search • Sequential processing • Con • Slow for retrieval information needed by management

7. Hash • Terminology • Hash field, hash key • Collision, synonyms • Bucket, slots • Types • Folding • Division-remainder • Collision handling • Open addressing or unchained overflow • Chained overflow • Multiple hashing

8. Direct (Random or Hash) • Pro • Random processing • Cons • Sequential processing • Updating (reorganization)

9. Indexes • Terminology • Primary index (one for each file) • Secondary index for unique field or non-unique field (several for each file) • Clustering index for clustering attribute (non-key field or non-unique field) • Sparse index for some of the search key values • Dense index for every search key value • Types • Linked list • Inverted file • Indexed sequential • B+-tree

10. Indexed Sequential • Structure • Prime area • Index area: track no, highest key on the track, highest key in the overflow, address of first overflow record • Overflow area: address, record, pointer • Types • Indexed Sequential Access Method (ISAM) • Virtual Sequential Access Method (VSAM) • Pro • Sequential & random processing • Con • Waste spaces (deletion) • Inefficient due to overflow

11. B+-Tree • Terminology • Node • Root • Parent • Child • Leaf • Depth: the maximum number of level • Balanced tree • Degree or order (n): the maximum number of children • Rules • Root having at least two children • Each node having n/2 and n pointers (children) • Key values in leaf have to be between (n-1)/2 and (n-1) • Max no. of key values in non-leaf is 1 less than pointer • Balanced tree • Ordered values in leaf

12. Points to Remember • Definition • Types of File Organization

13. Assignment • Review chapter 1 & appendix C • Read chapter 2 • Group list due date: 9/18/07 • Homework due date: