In the Redshift DDL (found on github) for the concept table, concept_name and concept_code may be null yet they are required fields. In the SQL, Oracle, and Postgresql DDLs these fields are “not null” as expected.
create table concept
(
concept_id integer not null,
concept_name varchar(255) null,
domain_id varchar(20) not null,
vocabulary_id varchar(20) not null,
concept_class_id varchar(20) not null,
standard_concept char(1) null,
concept_code varchar(50) null,
…
Also wrt the Redshift DDL…on the 5.2 wiki page, the observation_period does not show the observation_period_start_datetime and the observation_period_end_datetime fields but the ddls show those fields. Were those fields removed recently? Would you consider the wiki page as the source of truth?