During implementation of the Oracle OMOP CDM we ran into the issue of many of the _datetime fields being set to NOT NULL. I checked several of the other database flavors and they too had them created as not null. The standard in git has these fields defined as not required. My question is if the DDL needs to be modified to change these to optional or if the standard needs to be modified to reflect that these fields are required?
The first two for observation_period may be correct. The main issue with them is that they are not even included in the documentation on git. I believe they were added in 5.2. Perhaps the documentation is behind?
Here are the fields in question.
All other _datetime fields are consistent with the documentation. It appears that when the associated _date field was marked as required, the _datetime field was created as required in the DDL.