Modelling Conventions

Star Schemas

All Open Data Blend Datasets are created by using dimensional modelling techniques to optimise the data for data analysis. We carefully transform the source data into facts (i.e. the tables with columns containing measurable values such as the number of prescription items) and dimensions (i.e. tables with the columns containing descriptive values such as the name of a prescribed medicine).

There are a vast number of resources that explain what these modelling practices are and why they exist. Rather than reinventing the wheel, we recommend looking through this comprehensive glossary by the Kimball Group.

Naming Conventions

Column Prefixes

We use the following column prefixes in our data files:

Prefix	Description
nlm_	Metadata column*
nll_	Licence information column*
src_	Source column
srk_	Source column that is also a natural key
drv_	Derived column*
drk_	Derived column that is also a natural key*

*The values in these columns either originate from Open Data Blend or are derived from source columns by Open Data Blend.

Column Names

All column names are in lower-case, alpha-numeric (no special characters), and spaced using underscores. This is to ensure the broadest level of compatibility across all tools and platforms.

Acronym Handling

Acronyms are expanded to their corresponding word parts except for when the acronym is very well known and non-ambiguous. Even then, it may still be expanded.

Foreign Key References

Foreign key references are implied. It's safe to assume that whenever two tables each have a column name that starts with drv_ and ends with _key (e.g. drv_prescribing_practice_key), these columns are intended to be joined.