Week 1 - Introduction to AD Flashcards
(8 cards)
What is a database?
A database is a collection of records. Key features of a database include the capacity for shared access as well as containing a central repository.
What are the main components that make a database?
Files - Tables
Records - Rows
Fields - Columns
What is the definition of a data warehouse?
A data warehouse is a subject-oriented, integrated, time-variant and non-volatile collection of data in support of managements decision making process.
What are the main differences between an operational database (OLTP) and a data warehouse (DW)?
The main difference between an OLTP and a DW is that DW maintains historical data as opposed to OLTP which maintains current data.
Operational databases are organized by transactions, have many users and queries can be written to access entire tables. The database supporting an OLTP is small/medium in size.
In contrast, a DW is organised by a particular subject, which has fewer users, and queries can only access a few records.
What are some functions of data warehouse tools?
Data Extraction: Data is extracted from a data source.
Data Cleaning: Involves finding and correcting the errors in data.
Data Transformation: Involves converting the data from legacy format to warehouse format.
Data Loading: Involves sorting, summarising, consolidating, checking integrity, and building indices and partitions, then the data is loaded into the final target database.
Refreshing: Involves updating from data sources to warehouse.
Define metadata?
Metadata: The data that are used to represent other data is known as metadata.
For example, the index of a book serves as a metadata for the contents in the book.
What is a data mart?
Data marts contain a subset of organisation-wide data that is valuable to specific groups of people in an organisation.
A data mart contains only those data that is specific to a particular group.
Data Marts:
- Are small in size
- Data marts are customised by department
- The source of a data mart is departmentally structured DW.
- Data marts are flexible.
What does the DW Basic Architecture - Staging represent?
It represents everything that happens between the operational source system and the data presentation area.
