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2026-06-23

CDM Schema Reference

The Cohort Discovery Service is aligned with the OMOP Common Data Model (CDM), versions 5.3 and 5.4. This page provides reference links and key notes on schema compliance.


Official OMOP CDM documentation

The authoritative schema reference is maintained by OHDSI:

Version Documentation
OMOP CDM 5.3 ohdsi.github.io/CommonDataModel/cdm53.html
OMOP CDM 5.4 ohdsi.github.io/CommonDataModel/cdm54.html

Bunny deployment requirements

The Cohort Discovery minimum dataset is fully aligned with Bunny's deployment requirements. Always check the Bunny documentation for the latest supported versions and any additional configuration requirements:

Bunny deployment requirements


If you are using Bunny as your query retrieval software, ensure the following indexes are in place on your OMOP tables to support efficient query processing:

Index name Table
idx_person_id Person
idx_concept_concept_id Concept
idx_condition_concept_id_1 Condition Occurrence
idx_procedure_concept_id_1 Procedure Occurrence
idx_observation_concept_id_1 Observation
idx_measurement_concept_id_1 Measurement

See hutch.health/bunny/deployment/requirements for the full list of recommended indexes.

Example: creating an index on Person
CREATE INDEX idx_person_id ON person (person_id);

Schema compliance notes

Include all columns

When implementing any OMOP CDM table, all columns defined by the CDM schema should ideally be present in the table structure — even if some are not populated. This ensures forward compatibility as Bunny adds support for additional fields.

Vocabulary tables

The Concept table (concept_id, domain_id) is mandatory and must be populated. Cohort Discovery uses concept vocabulary lookups to translate query criteria into SQL filters against your OMOP data.