uni=# explain analyze
uni=# select s1.code, s2.code
uni-# from Subjects s1, Subjects s2
uni-# where s1.offeredBy = s2.offeredBy and s1.code < s2.code;
                        QUERY PLAN
---------------------------------------------------------------
Hash Join  (cost=1286.03..126135.12 rows=2371100 width=18)
           (actual time=7.356..6806.042 rows=3655437 loops=1)
  Hash Cond: (s1.offeredby = s2.offeredby)
  Join Filter: (s1.code < s2.code)
  Rows Removed by Join Filter: 3673157
  ->  Seq Scan on subjects s1 
          (cost=0.00..1063.79 rows=17779 width=13)
          (actual time=0.009..4.602 rows=17779 loops=1)
  ->  Hash  (cost=1063.79..1063.79 rows=17779 width=13)
            (actual time=7.301..7.301 rows=17720 loops=1)
        Buckets: 32768  Batches: 1  Memory Usage: 1087kB
        ->  Seq Scan on subjects s2
                (cost=0.00..1063.79 rows=17779 width=13)
                (actual time=0.005..4.452 rows=17779 loops=1)
Planning time: 0.159 ms
Execution time: 6949.167 ms