Create simple test case for failure to load PUDL into Postgresql

As @briannacote noted in #413, there’s some issue which prevents the loading of even an already flattened / simple PUDL data package into a postgres database. @roll thinks this is something which should actually work, but needs a test case to debug it and fix it in the data package libraries.

We need to come up with a simple test case that demonstrates the “non-unique foreign key” issue.

The error which gets thrown:

psycopg2.errors.InvalidForeignKey: there is no unique constraint matching given keys for referenced table "generators_entity_eia"

Resulting from this SQL:

CREATE TABLE ownership_eia860 (
	id SERIAL NOT NULL, 
	report_date DATE, 
	utility_id_eia INTEGER, 
	plant_id_eia INTEGER, 
	generator_id TEXT, 
	operational_status_code TEXT, 
	owner_utility_id_eia INTEGER, 
	owner_name TEXT, 
	owner_state TEXT, 
	owner_city TEXT, 
	owner_street_address TEXT, 
	owner_zip_code TEXT, 
	fraction_owned NUMERIC, 
	PRIMARY KEY (id), 
	FOREIGN KEY(utility_id_eia) REFERENCES utilities_entity_eia (utility_id_eia), 
	FOREIGN KEY(plant_id_eia) REFERENCES generators_entity_eia (plant_id_eia), 
	FOREIGN KEY(generator_id) REFERENCES generators_entity_eia (generator_id)
)

]
(Background on this error at: http://sqlalche.me/e/f405)

[roll]

Update

                "foreignKeys": [
                    {
                        "fields": "plant_id_eia",
                        "reference": {
                            "resource": "generators_entity_eia",
                            "fields": "plant_id_eia"
                        }
                    },
                    {
                        "fields": "generator_id",
                        "reference": {
                            "resource": "generators_entity_eia",
                            "fields": "generator_id"
                        }
                    }
                ],

probably should be a composite FK

[briannacote]

This is awesome! I’ll give it a go soon. I’ve also connected to the SQLite database as well. So we have options now over here. I’ll let you know if I run into any issues again trying it with Postgres.

Also, forgive my delay in getting back. I was out of the office the last two weeks.