Depends on which data files you loaded into postgres, and whether the mysql importer is up to date on the current schema (the latter seems unlikely).
I think this query returns all singles released between 1975 and 1984:
SELECT r.name, ac.name, rc.date_year, rc.date_month, rc.date_day
from release r
inner join release_group rg on r.release_group = rg.id
inner join artist_credit ac on r.artist_credit = ac.id
inner join release_country rc on rc.release = r.id
where rg.type = 2
and rc.date_year between 1975 and 1984
(would need tuning to remove multiple hits for the same release group etc); on my postgres db (set up a week or two ago) this seems to return over 12000 rows, which should be fine.