This repo contains the definition of the OMOP Common Data Model. It supports the SQL technologies: BigQuery, Impala, Netezza, Oracle, Parallel Data Warehouse, Postgres, Redshift, and SQL Server. For each, the DDL, constraints and indexes (if appropriate) are defined. Versions are defined using tagging and versioning. Full versions (V6, 7 etc.) are usually released each year (1-Jan) and are not backwards compatible. Minor versions (V5.1, 5.2 etc.) are not guaranteed to be backwards compatible though an effort is made to make sure that current queries will not break. Micro versions (V5.1.1, V5.1.2 etc.) are released irregularly and often, and contain small hot fixes or backward compatible changes to the last minor version.