ERROR: insufficient columns in PRIMARY KEY constraint definition
Yes, this is required.  There is no concept of an index over all
partitions in PostgreSQL.  The requirement of having the partition key
a subset of the primary key allows us to implement primary keys by
just having individual unique indexes on each partition.
There's mention in section 5.10.2.3. &quot;Unique constraints on
partitioned tables must include all the partition key columns. This
limitation exists because PostgreSQL can only enforce uniqueness in
each partition individually.
CREATE TABLE c_account_p
    (
        billing_account_guid character varying(40)  NOT NULL,
        ingestion_process_id bigint NOT NULL DEFAULT '-1'::integer,
        load_dttm timestamp(6) without time zone NOT NULL,
        ban integer NOT NULL,
        CONSTRAINT billing_account_pkey  PRIMARY KEY (billing_account_guid,ban,load_dttm)
    ) PARTITION by RANGE(load_dttm);