Recap of Mar 4: File Organization
• Major concepts:
– Files are made up of records; records are made up of fields
– Disk blocks are smaller than files and larger than records; files must be
split into disk blocks for storage (and the records in a file must be grouped
somehow for storage on disk blocks, independent of the file organization)
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Fixed-length records
Variable length records
Block structure: fixed-packed or slotted page
File structure: heap, sequential, hashed, or clustered
Details of the above file structures
Data Dictionary
The data dictionary (also called system catalog) stores
metadata -- data about data. For example:
• Information about relations
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names of relations
names and types of attributes of each relation
names and definitions of views
integrity constraints
• User and account information, including passwords
Data Dictionary
• Statistical and descriptive data
– number of tuples in each relation
• Physical file organization information
– how relation is stored (sequential, hash, clustered, etc.)
– physical location of relation -- operating system file name or disk
addresses of blocks containing records of the relation
• Information about indices
– (about which more after the midterm, when we cover chapter 12)
Data Dictionary
• In effect, the data dictionary is a mini database. The data
within can either be stored as:
– special-purpose data structures and code to access it, or
– a set of relations, using the existing database structures and code to
access it (most common solution)
Data Dictionary
Example of a possible system catalog representation:
Relation-metadata =
Attribute-metadata =
User-metadata =
Index-metadata =
View-metadata =
(relation-name, number-of-attributes,
storage-organization, location)
(attribute-name, relation-name, domain-type,
position, length)
(user-name, encrypted-password, group)
(index-name, relation-name, index-type,
index-attributes)
(view-name, definition)
Reading and Review
Upcoming dates:
– Mar 11: HW#2 is due
– Mar 11 and 13: midterm review
– Mar 18: midterm
Text Sections we’ve covered:
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Chapter 1: Introduction
Chapter 2: E-R data model
Chapter 3 (except 3.4 & 3.5): Relational model
Chapter 4: SQL
Chapter 6: Integrity and Security
Chapter 7 up to and including 7.7: Relational-Database Design
Chapter 11 (except 11.3 and 11.9): Storage and File Structure
Reading and Review
Chapter 1: Introduction
1.1: Applications and motivation
1.2: Database systems vs. file systems
1.3: Views
1.4: Data models
1.5: Database languages
1.6: Database users and administrators
1.7-1.10: other stuff
1.11: Summary
Reading and Review
Chapter 2: Entity-Relationship Model
2.1: Basic concepts: entities (entity-sets), relationship (set)s, and attributes
2.2: Constraints and mapping
2.3: Keys
2.4: Design issues
2.5: E-R Diagram
2.6: Weak entity sets
2.7: Extended E-R features (specialization, aggregation)
2.8: Design of an E-R schema
2.9: Reduction of an E-R schema to tables
2.10: (ignore)
2.11: Summary
Reading and Review
Chapter 3: Relational Model
3.1: Structure of relational databases
3.2: The relational algebra
3.3: Extended relational-algebra operations
3.4, 3.5: (ignore)
3.6: Tuple relational calculus
3.7: Domain relational calculus
3.8: Summary
Reading and Review
Chapter 4: SQL
4.1: Background
4.2: Basic structure
4.3: Set operations
4.4: Aggregate functions
4.5: Null values
4.6: Nested subqueries
4.7, 4.8: (ignore)
4.9: Modification of the database
4.10: (ignore)
4.11-4.14: (really ignore)
4.15: Summary
Reading and Review
Chapter 6: Integrity and Security
6.1: Domain Constraints
6.2: Referential Integrity
6.3: Assertions
6.4: Triggers
6.5: Security and Authorization
6.6, 6.7: (ignore)
6.8: Summary
Reading and Review
Chapter 7: Relational-Database Design
7.1: First Normal Form
7.2: Pitfalls in Relational-Database Design
7.3: Functional Dependencies
7.4: Decomposition
7.5: Desirable Properties of Decomposition
7.6: BCNF
7.7: Third Normal Form
7.8-7.10: (ignore)
7.11: Summary
Reading and Review
Chapter 11: Storage and File Structure
11.1: Overview of physical storage media
11.2: Magnetic Disks
11.3: RAID (not responsible for this)
11.4: Tertiary Storage
11.5: Storage Access
11.6: File Organization
11.7: Organization of Records in Files
11.8: Data Dictionary Storage
11.9: (ignore)
11.10: Summary