| 1 | ######## gradebook WITHOUT index ########
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| 2 | Sort (cost=3025.52..3027.18 rows=664 width=73) (actual time=16.122..16.143 rows=684.00 loops=1)
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| 3 | Sort Key: s.name, u.surname
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| 4 | Sort Method: quicksort Memory: 81kB
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| 5 | Buffers: shared hit=1965 read=152
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| 6 | -> Hash Join (cost=1699.04..2994.40 rows=664 width=73) (actual time=7.662..14.333 rows=684.00 loops=1)
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| 7 | Hash Cond: (ss.subjects_id = s.id)
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| 8 | Buffers: shared hit=1962 read=152
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| 9 | -> Hash Join (cost=1689.29..2979.56 rows=664 width=38) (actual time=7.580..13.939 rows=684.00 loops=1)
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| 10 | Hash Cond: (es.user_id = u.id)
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| 11 | Buffers: shared hit=1959 read=152
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| 12 | -> Nested Loop Left Join (cost=1518.59..2807.12 rows=664 width=13) (actual time=6.304..12.389 rows=684.00 loops=1)
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| 13 | Buffers: shared hit=1881 read=152
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| 14 | -> Hash Join (cost=1518.30..1978.94 rows=664 width=13) (actual time=6.270..9.008 rows=684.00 loops=1)
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| 15 | Hash Cond: (es.id = ss.enrolled_semesters_id)
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| 16 | Buffers: shared hit=664
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| 17 | -> Seq Scan on enrolled_semesters es (cost=0.00..314.00 rows=16000 width=8) (actual time=0.029..1.111 rows=16000.00 loops=1)
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| 18 | Buffers: shared hit=154
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| 19 | -> Hash (cost=1510.00..1510.00 rows=664 width=13) (actual time=6.211..6.212 rows=684.00 loops=1)
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| 20 | Buckets: 1024 Batches: 1 Memory Usage: 41kB
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| 21 | Buffers: shared hit=510
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| 22 | -> Seq Scan on semesters_subjects ss (cost=0.00..1510.00 rows=664 width=13) (actual time=0.038..6.061 rows=684.00 loops=1)
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| 23 | Filter: (professor_id = 47)
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| 24 | Rows Removed by Filter: 79316
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| 25 | Buffers: shared hit=510
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| 26 | -> Index Only Scan using ix_passed_subjects_enrolled_grade on passed_subjects ps (cost=0.29..1.25 rows=1 width=8) (actual time=0.005..0.005 rows=0.68 loops=684)
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| 27 | Index Cond: (enrolled_id = ss.id)
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| 28 | Heap Fetches: 0
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| 29 | Index Searches: 684
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| 30 | Buffers: shared hit=1217 read=152
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| 31 | -> Hash (cost=119.20..119.20 rows=4120 width=33) (actual time=1.225..1.225 rows=4120.00 loops=1)
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| 32 | Buckets: 8192 Batches: 1 Memory Usage: 336kB
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| 33 | Buffers: shared hit=78
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| 34 | -> Seq Scan on users u (cost=0.00..119.20 rows=4120 width=33) (actual time=0.013..0.614 rows=4120.00 loops=1)
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| 35 | Buffers: shared hit=78
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| 36 | -> Hash (cost=6.00..6.00 rows=300 width=22) (actual time=0.073..0.074 rows=300.00 loops=1)
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| 37 | Buckets: 1024 Batches: 1 Memory Usage: 25kB
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| 38 | Buffers: shared hit=3
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| 39 | -> Seq Scan on subjects s (cost=0.00..6.00 rows=300 width=22) (actual time=0.011..0.035 rows=300.00 loops=1)
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| 40 | Buffers: shared hit=3
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| 41 | Planning:
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| 42 | Buffers: shared hit=361
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| 43 | Planning Time: 10.951 ms
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| 44 | Execution Time: 16.332 ms
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| 45 | -- OK gradebook.sql
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