SELECT
*
, (SELECT placename
    FROM place
    JOIN namedplace USING (namedplace_id)
    WHERE
    place.plot_id = plot.plot_id
    AND placesystem = 'continent'
    LIMIT 1
    ) AS continent
, (SELECT placename
    FROM place
    JOIN namedplace USING (namedplace_id)
    WHERE
    place.plot_id = plot.plot_id
    AND placesystem = 'area|country|territory'
    LIMIT 1
    ) AS "area|country|territory"
, (SELECT placename
    FROM place
    JOIN namedplace USING (namedplace_id)
    WHERE
    place.plot_id = plot.plot_id
    AND placesystem = 'region|state|province'
    LIMIT 1
    ) AS "region|state|province"
, (SELECT placename
    FROM place
    JOIN namedplace USING (namedplace_id)
    WHERE
    place.plot_id = plot.plot_id
    AND placesystem = 'county'
    LIMIT 1
    ) AS county
, (SELECT placename
    FROM place
    JOIN namedplace USING (namedplace_id)
    WHERE
    place.plot_id = plot.plot_id
    AND placesystem = 'quadrangle'
    LIMIT 1
    ) AS quadrangle
, (SELECT placename
    FROM place
    JOIN namedplace USING (namedplace_id)
    WHERE
    place.plot_id = plot.plot_id
    AND placesystem = 'Geographic Name'
    LIMIT 1
    ) AS "Geographic Name"
FROM plot
-- runtime: 5 min ("319880.264 ms") @starscream