1. Short History of Data Storage

2. 1725 - 1975: Punch Cards Early data storage was very inefficient
Processing of data was very sequential
Data was stored as flat files (read from beginning to end)

3. Disk Drum - 10kB
Formed central memory and secondary storage, also primarily sequential, leading to flat files as best performant data storage.

4. 1951 - Magnetic Tape - 7200 characters / second
Tape allowed much greater data densities, but at slower access times.
Blocks of data were written to the tape with gaps where the tape is accelerated/decelerated, necessitating more advanced data processing procedures.

5. Hard Disk - 5MB
Disks allowed for much closer to random access memory than tapes.
This allowed the advent of data storage beyond flat files.

6. http://www.storagesearch.com/chartingtheriseofssds.html /
Solid State Drive - 2MB
SSDs are basically Random Access Memory (RAM) emulating Hard Disks and are optimized for storage instead of access time. /

7. Data + Base http://ed-thelen.org/SageIntro.html
1960 SAGE anti-aircraft command and control network
Cold War Era technology to track and coordinate many separate military installations.

8. Far more complex than any other computer project of the 1950s
The first major system to run in “real-time” – responding immediately to requests from its users and to reports from its sensors.
SAGE had to present an up- to-date and consistent representation of the various bombers, fighters and bases to all its users.
Popularized the term "data base" to refer to the data underlying the many different views allowed.

9. Corporate Conceptions of Databases
Robert V. Head, "Management Information Systems: A Critical Appraisal", Datamation 13, no. 5 (May 1967):22-27, page 24.

10. File based storage - 1968 Predecessor of databases Advantages
Limitations
Various access methods , e.g., sequential, indexed, random
Requires extensive programming
Separation and isolation: Each program maintains its own set of data
Duplication of data – same data is held by different programs, thus, wastes space and resources.
High maintenance costs such as ensuing data consistency and controlling access
Sharing granularity is very coarse.
Weak security.
Predecessor of databases

11. Hierarchical Database - 1968-1980
Advantages
Limitations
Efficient searching.
Complex implementation
Less redundant data.
Difficult to manage and lack of standards, can’t easily handle many-many relationships.
Data independence.
Lacks structural independence.
Database security and integrity.
Files are related in a parent/child manner, with each child file having at most one parent file.

12. Network Data Model - Early 1960s-1970s
Advantages
Limitations
Ability to handle more relationship types
System complexity and difficult to design and maintain
Ease of data access
Lack of structural independence as data access method is navigational.
Data Integrity
Data Independence
Network data model identified the following three database components:
Network schema—database organization[structure]
Sub-schema—views of database per user
Data management language — at low level, procedural

13. Relational Databases -1970-Present
Advantages
Limitations
Control of data redundancy, consistency, abstraction, sharing
Complexity, size, cost of DBMS
Improved data integrity, security, enforcement if standards and economy of scale
Higher impact of failure
Improved data accessibility and maintenance
Instance – a table with rows and columns.
Schema – specifies the structure (name of relation, name and type of each column)

14. Object Oriented Database -1980-Present
Advantages
Limitations
Can efficiently manage a large number of different data types.
Switching an existing database to OODBMS requires an entire change from scratch.
Objects with complex behaviors are easy to handle using inheritance and polymorphism etc.
An OODBMS is typically tied to a specific programming language and an API; this reduces its flexibility.
Reduces the large number of relations by creating objects.
Ad-hoc queries are difficult to implement as one cannot join two classes as one can join two tables in RDBMS.
It supports the modeling and creation of the data as objects.

15. History of Databases
Why was the development of Hard Disks important to databases?
Larger Storage Capacity
Block Segmentation
Low Latency
Nice Hum Noise