Unit 4 Readings

Wikipedia article: Database

A database is a structured collection of information store on a computer system. It has several models in which the information is arranged: relational, which is most used, heirarchical, and network.

In the relational model, information is presented in rows and columns, like an Excel spreadsheet. This model has three basic rules: 1. the order of the columns doesn't matter, 2. identical rows aren't allowed, 3. each row has one value for each column.

In the heirarchical model data is organized in an inverted tree, which is useful for establishing logical relationships between elements of multiple files. It is organized in parent child records, and each child has only one parent. It is good for one-to-many relationships, but isn't very flexible.

In the network model, a child can have multiple parents. It is very flexible, but pretty error prone for complex data models, one small change requires changes to many files, and its pretty time consuming. Is this model anything like a computer network, in which many computers are connected?

Databases have several different management systems:

• relational: information is represented in only one way. It follows the Information Principle
• post-relational: uses relations, but is not limited by the Information Principle
• object: tries to bring databases and applications together by making sure they use the same type of system

Introduction to Metadata: Pathways to Digital Information
Setting the Stage

Metadata is "data about data" or the "sum total of what can be said regarding any information object at any level of aggregation."

Information objects have:

• content-what the contains or is about
• context-indicates the who, what, why, where, how of an information object
• structure-formal set of associations within and among individual information objects.

Information professionals use the term metadata to describe enhanced access to information objects; its about providing intellectual and physical access to content.

The structure of metadata increased with the increased use of the internet, so with unmediated access metadata:

• certifies authenticity and degree of completeness
• establishes and documents context of content
• identifies and exploits relationships between and with information objects
• provides range of access points for lots of users
• provides information a professional could have traditionally provided.

The term metadata applies to different kinds of information in different fields. It is a very broad term, but also specialized.

Metadata doesn't have to be digital. Information professional have been using it for years and years in cataloguing materials and making them more accessible to the public.

Some new issues (ones that I could particularly identify with/understand)

• Increased accessibility
• Retention of context: it is part of metadata's job to ensure that an information object doesn't get lost off all by itself
• Preservation: how do we adapt metadata to exist independently of the places it is currently stored so we don't lose it?

WEEK 3 MUDDIEST POINT:

Regarding fragmented files: does the computer know where the different fragments of a file are and automatically jump from one piece to the next, or does the user need to know where the fragments are and manually jump to them?

Also, what is the difference between the FAT and NTFS file systems?