1. Appendix C File Organization & Storage Structure

2. Agenda Definition Types of Storage 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 –Primary 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 –Balanced tree –Degree or order (n) Rules –Root having two children –Each node having n/2 and n pointers (children) –Key values in leaf between (n-1)/2 and (n-1) –Key values in non-leaf is 1 less than pointer –Balanced tree –Ordered values in leaf

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

13. Assignment Review appendix c Read chapters 1 and 2 (skip relational calculus) Homework due date: