Shrunken Dimension

A shrunken dimension is a subset of a dimension’s attributes that apply to a higher summary level. For example, a Month dimension would be a shrunken dimension of the Date dimension. The Month dimension could be connected to a forecast fact table whose grain is at the monthly level.

(Sales Dimension Example)

Suppose you have a dataset with 100 features (or variables) that describe some phenomenon. However, you suspect that not all of these features are relevant to predicting the outcome you're interested in. You suspect many of these features are noisy, redundant, or irrelevant.

CREATE TABLE dim_patient (
    PatientID INT PRIMARY KEY,
    Name String,
    Age INT,
    Gender String,
    Race String,
    Height DECIMAL,
    Weight DECIMAL
    EyeColor String,
    ...
    ...
);

In this shrunken dimension, you're reducing the attribute 
set to only those necessary for BMI analysis, 
simplifying the data model for this specific use case.

CREATE TABLE dim_patient_bmi(
    PatientID INT Primary KEY,
    Name String,
    Height DECIMAL,
    Weight DECIMAL,
    BMI DECIMAL
)