Rafael dos Santos Silva 48d161e3b1 PERF: Add partial index on reviewables for topic view (#10492) ... On the topic view route we query for reviewables of each post in the stream, using a query that filters on two unindexed columns. This results in a Parallel Seq Scan over all rows, which can take quite some time (~20ms was seen) on forums with lots of flags After index is added PostgreSQL planner opts for a simple Index Scan and runs in sub 1ms. Before: ``` QUERY PLAN --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Finalize GroupAggregate (cost=11401.08..11404.87 rows=20 width=28) (actual time=19.209..19.209 rows=1 loops=1) Group Key: r.target_id -> Gather Merge (cost=11401.08..11404.41 rows=26 width=28) (actual time=19.202..20.419 rows=1 loops=1) Workers Planned: 2 Workers Launched: 2 -> Partial GroupAggregate (cost=10401.06..10401.38 rows=13 width=28) (actual time=16.958..16.958 rows=0 loops=3) Group Key: r.target_id -> Sort (cost=10401.06..10401.09 rows=13 width=16) (actual time=16.956..16.956 rows=0 loops=3) Sort Key: r.target_id Sort Method: quicksort Memory: 25kB Worker 0: Sort Method: quicksort Memory: 25kB Worker 1: Sort Method: quicksort Memory: 25kB -> Nested Loop (cost=0.42..10400.82 rows=13 width=16) (actual time=15.894..16.938 rows=0 loops=3) -> Parallel Seq Scan on reviewables r (cost=0.00..10302.47 rows=8 width=12) (actual time=15.882..16.927 rows=0 loops=3) Filter: (((target_type)::text = 'Post'::text) AND (target_id = ANY ('{7565483,7565563,7565566,7565567,7565568,7565569,7565579,7565580,7565583,7565586,7565588,7565589,7565601,7565602,7565603,7565613,7565620,7565623,7565624,7565626}'::integer[]))) Rows Removed by Filter: 49183 -> Index Scan using index_reviewable_scores_on_reviewable_id on reviewable_scores s (cost=0.42..12.27 rows=2 width=8) (actual time=0.029..0.030 rows=1 loops=1) Index Cond: (reviewable_id = r.id) Planning Time: 0.318 ms Execution Time: 20.470 ms ``` After: ``` QUERY PLAN ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ GroupAggregate (cost=0.84..342.54 rows=20 width=28) (actual time=0.038..0.038 rows=1 loops=1) Group Key: r.target_id -> Nested Loop (cost=0.84..341.95 rows=31 width=16) (actual time=0.020..0.033 rows=1 loops=1) -> Index Scan using index_reviewables_on_target_id on reviewables r (cost=0.42..96.07 rows=20 width=12) (actual time=0.013..0.026 rows=1 loops=1) Index Cond: (target_id = ANY ('{7565483,7565563,7565566,7565567,7565568,7565569,7565579,7565580,7565583,7565586,7565588,7565589,7565601,7565602,7565603,7565613,7565620,7565623,7565624,7565626}'::integer[])) -> Index Scan using index_reviewable_scores_on_reviewable_id on reviewable_scores s (cost=0.42..12.27 rows=2 width=8) (actual time=0.005..0.005 rows=1 loops=1) Index Cond: (reviewable_id = r.id) Planning Time: 0.253 ms Execution Time: 0.067 ms ```		2020-09-08 10:49:08 -07:00
..
fixtures	FIX: Use a mutex when reseting column information while seeding.	2020-06-23 09:15:47 +08:00
migrate	PERF: Add partial index on reviewables for topic view (#10492)	2020-09-08 10:49:08 -07:00
post_migrate	DEV: Correct historical posts table schema discrepancies (#10014)	2020-06-11 11:45:46 +01:00
api_test_seeds.rb	DEV: enable frozen string literal on all files	2019-05-13 09:31:32 +08:00