What is a Database SECTION 1 Database Technology

What is a Database? SECTION 1

Database Technology and its Evolution • Decades long evolution • Early data processing systems • Today's systems • New technology

File-Oriented Systems • Early business computer systems • Data processing systems • Sequential processing • Application program

Data from a File. Oriented System

Random Access Processing • Limitations of sequential processing systems • Sequential processing leads to additional work • Solved by :

Limitations of Traditional File Systems • Data redundancy • Poor data control • Inadequate data manipulation capabilities • Excessive programming effort

Information as a Resource • What is an Information System (IS)? • A Management Information System (MIS) • Data • Information

• A database system • Database Management System

Database Systems • Data models • Hierarchical model • Pointer

Files with a Hierarchical Relationship

CUSTOMER INVOICE LINE

CUSTOMER INVOICE STORE INVOICE LINE CONTACT

• A network model SALES REP CUSTOMER INVOICE STORE INVOICE LINE CONTACT

Relational Databases Systems • Pointers - strengths and weaknesses • E. F. Codd (1970)

An Illustration of Problems with Pointers • For each customer, identify the manufacturer of the ordered products. No physical connection CUSTOMER INVOICE MANUFACTURER INVOICE LINE PRODUCT

Codd’s proposal • Tables • Manipulation languages

Database Systems: Hardware, Software, Data, and People • A complete database systems consists of: 1 Hardware 2 Software – DBMS – Application software

DBMS • Data dictionary • Data security and integrity

Database User View 3 User View 2 User View 1 Data Item

3 Data 4 People

Database & Instance Typical components of a server Memory (RAM) Disk CPU

Database: The actual database is a collection of tables or files that reside on the disk Database Table 1 Table 4 Table 2 Table 5 Table 3 Table n Memory (RAM) CPU Two main types of database files: Data Metadata

Instance: Software running in memory Memory (RAM) Disk DBMS Database Table 1 Table 4 Table 2 Table 5 Table 3 Table n Instance CPU

An Instance: Multiple databases Memory (RAM) Disk DBMS DB 01 Table 4 Table 2 Table 5 Table 3 Table n Instance DB 02 Table 1 Table 4 Table 2 Table 5 Table 3 Table n CPU

Multiple Instances: Single database Memory (RAM) Disk DBMS Instance 01 Database Instance 02 Table 1 Table 4 Table 2 Table 5 Table 3 Table n CPU

Multiple Instances: Single database Memory (RAM) DBMS Disk Instance 01 Database Table 1 Table 4 Table 2 Table 5 Table 3 Table n CPU 01 Memory (RAM) DBMS Instance 02 CPU 02

INSTANCE OASIS Multiple databases