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Introducing the OMOP CDM ER diagram challenge! Submissions due 13Dec2022

Thank you so much Patrick! This is a great challenge and I am excited to see what the community comes up with! I have heard from some collaborators in the past requesting an ERD so I know this will be a well-used resource. I know @DMStep and @stephanieshong will certainly be interested, among others. Please don’t hesitate to throw your hat in the ring, hopefully our resident artists like @sseager will also contribute :star_struck:


For the less technical folks in OHDSI, I want to share a favorite “OHDSI-ism” I recall from the 2017 F2F Meeting at Georgia Tech.

As @nigehughes would say, “gather round, children…”

At that 2017 F2F, when going around the table during an initial icebreaking session, someone prompted the group, “what is your tool of choice?” People went around saying things like, R or SQL. @gregk, not missing a beat, proudly told the room, “PowerPoint.” :wink:

I still laugh about this because, at the time, I was a management consultant and my technical chops weren’t anywhere close to what they are now – which is, proudly, a full-blown pretengineer status.

I’ll throw my hat in the ring to commit to an entry! Let the games begin!!

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To keep things going, hereby my work in progress. The general idea that I want to work out further in the coming week: make the diagram person-centric. Person table in the centre. A first layer with the visit tables, observation_period and death. The main clinical event tables are in a layer around that. Then a layer with the era tables and the health system tables.
OMOP CDM - Person centric.pdf (169.0 KB)

A next layer would be health economics. The vocabulary tables would be the last layer. I have not worked out yet how to integrate that without creating a mess of relationships.

The tool dbdiagram.io - Database Relationship Diagrams Design Tool lets you create simple diagrams for free. It works directly from the browser and you do not need to create an account before you can start using.

I imported the PostgreSQL DDL for CDM v5.4, this is the result:

It’s not sophisticated, but here’s my point: if someone with less technical ability would like to just reorganize a diagram, with the mouse, to sketch an even better way to dispose the CDM tables and their connecting lines, this tool would be ideal. Just copy-paste the definitions from the link above into your own new diagram inside the tool. It’s also possible to grant editing privileges to others when sharing a diagram.

I’ve got three entries.

OMOP 5.4 ERD compact
OMOP 5.4 ERD Compact.pdf (1007.1 KB)
This shows the tables, primary keys, and the relationships, but not the foreign keys.

OMOP 5.4 ERD Standard
OMOP 5.4 ERD Standard.pdf (1007.1 KB)
Which adds the foreign keys.

OMOP 5.4 ERD Extended
OMOP 5.4 ERD Extended.pdf (1.0 MB)
Which shows all of the fields in the tables as well.

The more detail there is, the larger the diagram. I’m partial to the Standard version.


So @schuemie and myself partnered up for a little powerpoint party.
Hope it brings as much fun to the community as we had making it :slight_smile:

(The ppt file will be uploaded to the Teams site, as I’m not allowed to upload it here.)

CDM54_SchuemieLos.pdf (218.2 KB)


awesome thanks @RenskeLos and @schuemie , I love the coloring of the relationship lines, that makes it much clearer than my version about where the line comes from. and thanks for the ppt version, that should make it very easy for anyone else in the community to build on your version without needing any technical tools.

@roger.carlson , thanks for these. That’s a clever use of extending the CONCEPT table so that you could have cleaner lines between the tables, since most other tables have one or more links into the vocabulary. Great stuff!

Impressed by the submissions so far!

Hereby my submission, going for a programmers approach. Last year, I discovered the Mermaid syntax with which you can easily render diagrams within markdown documents. This is now also supported by Github for comments and markdown files.

I have created a simple script that takes the CDM definition from the CommonDataModel repository and puts this in mermaid syntax. Unfortunately, mermaid currently does not allow any customisation (not even colouring). So this submission is not for printing, but to use on Github. You can copy the syntax for specific tables, put it in mermaid code highlighting, and it will render the ER diagram.

See this PR for a few examples rendered by Github and the R code used to generate the diagrams: https://github.com/OHDSI/CommonDataModel/pull/540

Full diagram (following the link will render the diagram).


Hi OHDSI Friends, Hope you all are doing great…! my name is Thanuj Shiva Kumar (Sr.Big Data Engineer) from Odysseus Data Services Inc. I always wanted to contribute something towards OHDSI but haven’t really had a chance. Thank you @gregk for supporting me to take up this challenge to explore and contribute towards this great Initiative hosted by OHDSI @Patrick_Ryan and Team. So here is my first post and first submission. :blush:. I am all ears to your feedback and thoughts

ER Link :- https://omop.odysseusinc.com/

Tools used :-

Visual Paradigm 17.0 (Standard Edition) & Google Chrome Web Browser

Features :-

  • Web based Portal supports by most of the Web Browsers
  • HTML support (this can be hosted as a website on any DNS on the internet)
  • Interactive style report – Supports Interaction with the ER objects on the Website
  • Navigation Panel - Enables to traverse through Entities and their descriptions, Relationships, constraints, Models and Diagrams on the Website.
  • Supports Reverse Engineering and DDL Generation ( DDl’s can be reversed to Diagrams and vice versa)
  • Color Legends- ( Helps in categorizing the type of the OMOP Specified Objects )
  • Downloadable formats supported:- SVG,JPG,PNG,TIFF,EPS,EMF, PDF(Diagram per page), PDF (Diagram per file)

ER Model Generation Information :-

  • OMOP Version DDL’s used :- 5.4
  • Database Type Used:- PostgreSQL
  • ER Model Built Type:- Physical Model

OMOP Specification Objects :-

  • Clinical Data Tables
  • Health System Data Tables
  • Health Economics Data Tables
  • Standardized Derived Elements
  • Metadata Tables
  • Vocabulary Tables

ER Objects:

  • Entities
  • Attributes
  • Data Types
  • Constraints
  • Relationships
  • Cardinality ( Crow Foot Notation)


  • Descriptions for Each Field , Entities and Relationships
  • Links to Athena and OHDSI

Recommended Future Improvements :-

  • Color coding for the Entities should be muted
  • Some fields need to be adjusted/ added
  • Sort all attributes based on their type in Entities
  • Padding of diagram as the connectors on the left is nearly towards the navigation pane

Downloadable Formats :- (Jpeg)

Standard_Tables :-

Vocabulary_Tables :-

Vocabulary_With_Standard_Tables :-

Thanuj Shiva Kumar


just to add to TJ’s (@ThanujShivaKumar ) post…

What I like about a solution that TJ posted:

  • the end result is web-based, allows someone to easily explore the model and do a drill down for each element.
  • we can add any numbers of sub-views
  • all elements are annotated, including a descriptions as well as constraints for all key elements
  • color coding makes it easy to group elements by domains, similar to our classic logical CDM

Some other thoughts to share:

  • ERDs are platform specific. All database platforms do share share some elements (tables, columns) but could differ quite a bit in types, logical to ER implementation, presence or lack of certain elements, indexes, constrains etc… (RDBMS vs. MPP is a great example). Are we really looking to have separate ERDs for all supported dialects / databases? Could we all agree on the purpose of us publishing the ER diagram (s)?
  • there is a quite old standard published by OMG called Model Driven Architecture (MDA - Model Driven Architecture (MDA) | Object Management Group). It really didn’t take off at scale but there are some really attractive ideas that it put forward, including the idea that the Platform Specific Models (PSM) - including Class Diagrams, ERDs etc…- as well as Code can be automatically generated using platform specific transformations (software components that consume and model and spit out an output model/code). Maybe we should think about that approach? Funny enough, this idea has somewhat been already implemented when we generate DDLs via code.

Thanks @ThanujShivaKumar and @gregk , I agree its nice to have a web-based solution. Greg makes a good point, within OHDSI we try to support multiple RDMBS platforms. Our ERDs show table names, field names, and relationships, which should all be platform agnostic. The datatypes can be platform-specific, I wonder if there’s a way to display that in our figure to note where the graphic varies by target RDBMS (I’m not exactly sure what all of those are: BIGINT vs. INT4?). The other point is about indexes and constraints, though I dont think any ERDs are currently display this information.

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actually, you can see all those details in the ERD we generated - FK, PK and constraints.

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Hi @Patrick_Ryan , Below is the notation where you can easily identify PK, FK and constraints by looking at the objects, in future we can also add a legend for the below representation.

  • The :key: Key icon beside the Table column Field indicates Primary key.
  • The Outward Green arrow to any Table field indicates Foreign Key.
  • The Key with outward Green arrow indicates Primary Key and Foreign Key.
  • The ‘N’ in the table fields indicates ‘Nulls are Allowed’

The better and stable option is to drill down by just clicking on any table on the website and it directs to its respective table page where PK,FK and constraints and other details are provided as @gregk posted.

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Question: Do these ER diagrams document the “logical” (database-agnostic) or “physical” (database-specific) model?
If they are ‘physical’ then don’t we need a different one for each database system?


They are logical, not physical. If you want physical, go to the CDM and grab the DBMS implementation of your choice to do a diagram of, although, even there, the full physical model is not complete.

I would say that the ERD diagrams that we did as an exercise are actually physical models. Most of them targeted a very specific database platform - PostgreS - and were just a result of a reverse engineering the existing schema and then making it look good. Logical models do not have a notion of a Primary/Foreign key - they show named entities, key platform independent attributes and relationships between entities.

I would also say that it is wrong to say that the same logical model (OMOP CDM) will have the same ERD and physical implementation for all databases. So yes - you are correct that each database would have to have an ERD implementation of the logical model. They will be similar but not the same

Interesting. Two different answers! :slight_smile: @Christian_Reich what do you say? Are these ERDs logical or physical?

@gregk is correct, I misspoke.

So if the ERDs are physical then they are dbms specific, right?