COMP3005 - History and Models

Data Models

1. Hierarchical Model - IDS 1967 2. Network Model - IDMS 1966 3. Relational Model - 1970 Ingres (1976), System R (1977) 4. Nested Relational Model 5. Object Models 6. Object Relational Model 7. XML Model 8. NoSQL Models

Integrated Data Store (IDS)

1960s IDS stored and manipulated metadata about records and their relationships. Could enforce relationships between record types. Protected DB integrity.

Network Model Advantages

Able to model complex relationships and represent semantics of add/delete on them Can handle most situations using record and relationship types Language is navigational, FIND, FIND member, FIND owner, FIND NEXT within SET, GET... Programmers can do optimal navigation through DB

Larry Ellison

Created Oracle - a relational DB on unix Ricc AF

Hierarchical Model

Data stored as records which are collections of fields, each field containing only one value. All attributes of a specific record are listed under an entity type. Records are connected through links. Each record having one parent and many children. (Tree like model). One-to-many

Network Model

Introduced by Charles Bachman Data organized into a graph (lattice) structure. Allows each record ot have multiple parent and child records, forming a generalized graph structure. - schema is a generalized graph of record types connected by relationships - db is a generalized record of occurrences connected by relationships Many to Many

Hierarchical Model Disdvantages

Navigation and procedural nature of processing Linear arrange of records Little scope for optimization Cannot represent many to many

Network Model Disadvantages

Navigational and procedural nature of processing Database contains a complex array of pointers that thread through a set of records. Little scope for automated "query optimization"

Hierarchical Model Advantages

Simple to construct and operate Many naturally occurring hierarchies that it could model Simple language

M. Stonebraker

Turing Award 2014 - Age 71 Invented Object Relational model

C Bachman

Turing award 1973 - Age 49 Introduced network model

E. F. COdd

Turing award 1981 - Age 58 Introduced relational model

Jim Gray

Turing award 1998 - Age 54 Invented transaction processing

Relational model

all data is represented in terms of tuples (records), grouped into relations (files) Summary: - Proposed in 1970 by E.F. Codd (IBM), first commercial system in 1981-82. - Now in several commercial products (e.g. DB2, ORACLE, SYBASE, INFORMIX, SQL Server,). - Several free open source implementations, e.g. MySQL, - Currently most dominant for developing database applications. - SQL relational standards: SQL-89 (SQL1), SQL-92 (SQL2), SQL-99, SQL3,