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File Organization and Storage Structures Overview

Learn about file organization types such as Heap, Sequential, Hash, and Index. Understand the pros and cons of each method to optimize data retrieval and storage efficiency.

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File Organization and Storage Structures Overview

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  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:

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