OLAP Flashcards
OLAP
Online Analytical Processing
OLAP software
Enables multi-dimensional analysis of data.
Multi-dimensional analysis?
Users can look at data from many different dimensions at the same time
And can request which dimensions they wish to look at the data across
Relational OLAP
Data is stored in a relational database.
Can store or calculate data summaries
Can create a star schema to view data across dimensions
MOLAP (multidimensional)
Data is stored in a multidimensional database.
Each cell in the DB is a in a hypercube array at the intersection of all dimensions
Limited space - some cells can be empty
HOLAP (hybrid)
High level data is stored in multidimensional database and underlying is in original tables
Needs a robust link between multidimensional DB part and underlying base data
Slice and dice
Data is understood in 2D
So we constrain other dimensions (by picking values or summarising) and display only the slide of data we want (the dimension we want)
Drill across
To take a different slice of the data