#	exclusive	inclusive	rows x	rows	loops	node
1.	0.004	0.043	↑ 1.0	1	1	→ Nested Loop (cost=1.14..14.12 rows=1 width=53) (actual time=0.042..0.043 rows=1 loops=1)
2.	0.005	0.033	↑ 1.0	1	1	→ GroupAggregate (cost=0.57..5.51 rows=1 width=13) (actual time=0.033..0.033 rows=1 loops=1) Group Key: musician_scores.attribute_code
3.	0.028	0.028	↑ 6.2	5	1	→ Index Only Scan using idx_ms_musicid_createat on musician_scores (cost=0.57..5.34 rows=31 width=13) (actual time=0.020..0.028 rows=5 loops=1) Index Cond: ((musician_id = 32) AND (attribute_code = 'yt01'::text) AND (created_at <= '2019-04-14 10:36:02+00'::timestamp with time zone) AND (created_at >= '2019-02-13 00:00:00'::timestamp without time zone)) Heap Fetches: 5
4.	0.006	0.006	↑ 1.0	1	1	→ Index Scan using idx_ms_musicid_createat on musician_scores m (cost=0.57..8.59 rows=1 width=53) (actual time=0.006..0.006 rows=1 loops=1) Index Cond: ((musician_id = 32) AND ((attribute_code)::text = (musician_scores.attribute_code)::text) AND (created_at = (max(musician_scores.created_at))))

Nested Loop  (cost=1.14..14.12 rows=1 width=53) (actual time=0.042..0.043 rows=1 loops=1)
  ->  GroupAggregate  (cost=0.57..5.51 rows=1 width=13) (actual time=0.033..0.033 rows=1 loops=1)
        Group Key: musician_scores.attribute_code
        ->  Index Only Scan using idx_ms_musicid_createat on musician_scores  (cost=0.57..5.34 rows=31 width=13) (actual time=0.020..0.028 rows=5 loops=1)
              Index Cond: ((musician_id = 32) AND (attribute_code = 'yt01'::text) AND (created_at <= '2019-04-14 10:36:02+00'::timestamp with time zone) AND (created_at >= '2019-02-13 00:00:00'::timestamp without time zone))
              Heap Fetches: 5
  ->  Index Scan using idx_ms_musicid_createat on musician_scores m  (cost=0.57..8.59 rows=1 width=53) (actual time=0.006..0.006 rows=1 loops=1)
        Index Cond: ((musician_id = 32) AND ((attribute_code)::text = (musician_scores.attribute_code)::text) AND (created_at = (max(musician_scores.created_at))))
Planning time: 0.316 ms
Execution time: 0.082 ms

Per node type stats

node type	count	sum of times	% of query
GroupAggregate	1	0.005 ms	11.6 %
Index Only Scan	1	0.028 ms	65.1 %
Index Scan	1	0.006 ms	14.0 %
Nested Loop	1	0.004 ms	9.3 %

Per table stats

Table name	Scan count	Total time	% of query
scan type	count	sum of times	% of table
musician_scores	2	0.034 ms	79.1 %
Index Only Scan	1	0.028 ms	82.4 %
Index Scan	1	0.006 ms	17.6 %

explain.depesz.com

PostgreSQL's explain analyze made readable

Result: UvN9

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Per node type stats

Per table stats