######## gradebook WITH index ########
Sort  (cost=2048.55..2050.22 rows=666 width=73) (actual time=7.428..7.447 rows=684.00 loops=1)
  Sort Key: s.name, u.surname
  Sort Method: quicksort  Memory: 81kB
  Buffers: shared hit=2031 read=2
  ->  Nested Loop Left Join  (cost=1042.40..2017.32 rows=666 width=73) (actual time=4.026..6.081 rows=684.00 loops=1)
        Buffers: shared hit=2028 read=2
        ->  Hash Join  (cost=1042.11..1185.19 rows=666 width=52) (actual time=4.009..4.875 rows=684.00 loops=1)
              Hash Cond: (ss.subjects_id = s.id)
              Buffers: shared hit=659 read=2
              ->  Hash Join  (cost=1032.36..1173.67 rows=666 width=38) (actual time=3.929..4.688 rows=684.00 loops=1)
                    Hash Cond: (u.id = es.user_id)
                    Buffers: shared hit=656 read=2
                    ->  Seq Scan on users u  (cost=0.00..119.20 rows=4120 width=33) (actual time=0.006..0.274 rows=4120.00 loops=1)
                          Buffers: shared hit=78
                    ->  Hash  (cost=1024.04..1024.04 rows=666 width=13) (actual time=3.903..3.903 rows=684.00 loops=1)
                          Buckets: 1024  Batches: 1  Memory Usage: 41kB
                          Buffers: shared hit=578 read=2
                          ->  Hash Join  (cost=563.39..1024.04 rows=666 width=13) (actual time=1.575..3.817 rows=684.00 loops=1)
                                Hash Cond: (es.id = ss.enrolled_semesters_id)
                                Buffers: shared hit=578 read=2
                                ->  Seq Scan on enrolled_semesters es  (cost=0.00..314.00 rows=16000 width=8) (actual time=0.007..0.856 rows=16000.00 loops=1)
                                      Buffers: shared hit=154
                                ->  Hash  (cost=555.06..555.06 rows=666 width=13) (actual time=1.558..1.559 rows=684.00 loops=1)
                                      Buckets: 1024  Batches: 1  Memory Usage: 41kB
                                      Buffers: shared hit=424 read=2
                                      ->  Bitmap Heap Scan on semesters_subjects ss  (cost=9.45..555.06 rows=666 width=13) (actual time=0.108..1.480 rows=684.00 loops=1)
                                            Recheck Cond: (professor_id = 47)
                                            Heap Blocks: exact=424
                                            Buffers: shared hit=424 read=2
                                            ->  Bitmap Index Scan on ix_semesters_subjects_professor  (cost=0.00..9.29 rows=666 width=0) (actual time=0.070..0.070 rows=684.00 loops=1)
                                                  Index Cond: (professor_id = 47)
                                                  Index Searches: 1
                                                  Buffers: shared read=2
              ->  Hash  (cost=6.00..6.00 rows=300 width=22) (actual time=0.074..0.074 rows=300.00 loops=1)
                    Buckets: 1024  Batches: 1  Memory Usage: 25kB
                    Buffers: shared hit=3
                    ->  Seq Scan on subjects s  (cost=0.00..6.00 rows=300 width=22) (actual time=0.012..0.037 rows=300.00 loops=1)
                          Buffers: shared hit=3
        ->  Index Only Scan using ix_passed_subjects_enrolled_grade on passed_subjects ps  (cost=0.29..1.24 rows=1 width=8) (actual time=0.001..0.001 rows=0.68 loops=684)
              Index Cond: (enrolled_id = ss.id)
              Heap Fetches: 0
              Index Searches: 684
              Buffers: shared hit=1369
Planning:
  Buffers: shared hit=373 read=1
Planning Time: 11.015 ms
Execution Time: 7.615 ms
-- OK gradebook.sql