exports.up = async function(knex) {
	await knex.schema.createMaterializedView('media_sfw', (view) => {
		view.as(knex('media').select('id').where('is_sfw', true));
	});

	await knex.raw('CREATE UNIQUE INDEX media_sfw_id ON media_sfw(id)');

	await knex.raw(`
		CREATE OR REPLACE FUNCTION get_random_sfw_media_id() RETURNS varchar AS $$
			SELECT id FROM media_sfw
			ORDER BY random()
			LIMIT 1;
		$$ LANGUAGE sql STABLE;
	`);
};

exports.down = async function(knex) {
	await knex.raw(`
		CREATE OR REPLACE FUNCTION get_random_sfw_media_id() RETURNS varchar AS $$
			SELECT id FROM media
			WHERE is_sfw = true
			ORDER BY random()
			LIMIT 1;
		$$ LANGUAGE sql STABLE;
	`);

	await knex.schema.dropMaterializedView('media_sfw');
};