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63a0466548
Optimize `UserStatpost_read_count` calculation.
In addition, tests were updated to fail when code is not evaluated. Creation of PostTiming was updating `post_read_count`. Count it has to be reset to ensure that ensure_consitency correctly calculates result.
Extracting users seen in the last hour to separate Common Table Expression reduces the amount of processed rows.
Before
```
Update on user_stats (cost=267492.07..270822.95 rows=2900 width=174) (actual time=12606.121..12606.127 rows=0 loops=1)
-> Hash Join (cost=267492.07..270822.95 rows=2900 width=174) (actual time=12561.814..12603.689 rows=10 loops=1)
Hash Cond: (user_stats.user_id = x.user_id)
Join Filter: (x.c <> user_stats.posts_read_count)
Rows Removed by Join Filter: 67
-> Seq Scan on user_stats (cost=0.00..3125.34 rows=75534 width=134) (actual time=0.014..39.173 rows=75534 loops=1)
-> Hash (cost=267455.80..267455.80 rows=2901 width=48) (actual time=12558.613..12558.617 rows=77 loops=1)
Buckets: 4096 Batches: 1 Memory Usage: 39kB
-> Subquery Scan on x (cost=267376.03..267455.80 rows=2901 width=48) (actual time=12168.601..12558.572 rows=77 loops=1)
-> GroupAggregate (cost=267376.03..267426.79 rows=2901 width=12) (actual time=12168.595..12558.525 rows=77 loops=1)
Group Key: pt.user_id
-> Sort (cost=267376.03..267383.28 rows=2901 width=4) (actual time=12100.490..12352.106 rows=2072830 loops=1)
Sort Key: pt.user_id
Sort Method: external merge Disk: 28488kB
-> Nested Loop (cost=1.28..267209.18 rows=2901 width=4) (actual time=0.040..11528.680 rows=2072830 loops=1)
-> Nested Loop (cost=0.86..261390.02 rows=13159 width=8) (actual time=0.030..3492.887 rows=3581648 loops=1)
-> Index Scan using index_users_on_last_seen_at on users u (cost=0.42..89.71 rows=28 width=4) (actual time=0.010..0.201 rows=78 loops=1)
Index Cond: (last_seen_at > '2023-04-11 00:22:49.555537'::timestamp without time zone)
-> Index Scan using index_post_timings_on_user_id on post_timings pt (cost=0.44..9287.60 rows=4455 width=8) (actual time=0.081..38.542 rows=45919 loops=78)
Index Cond: (user_id = u.id)
-> Index Scan using forum_threads_pkey on topics t (cost=0.42..0.44 rows=1 width=4) (actual time=0.002..0.002 rows=1 loops=3581648)
Index Cond: (id = pt.topic_id)
Filter: ((deleted_at IS NULL) AND ((archetype)::text = 'regular'::text))
Rows Removed by Filter: 0
Planning Time: 0.692 ms
Execution Time: 12612.587 ms
```
After
```
Update on user_stats (cost=9473.60..12804.30 rows=2828 width=174) (actual time=677.724..677.729 rows=0 loops=1)
-> Hash Join (cost=9473.60..12804.30 rows=2828 width=174) (actual time=672.536..677.706 rows=1 loops=1)
Hash Cond: (user_stats.user_id = x.user_id)
Join Filter: (x.c <> user_stats.posts_read_count)
Rows Removed by Join Filter: 54
-> Seq Scan on user_stats (cost=0.00..3125.34 rows=75534 width=134) (actual time=0.012..23.977 rows=75534 loops=1)
-> Hash (cost=9438.24..9438.24 rows=2829 width=48) (actual time=647.818..647.822 rows=55 loops=1)
Buckets: 4096 Batches: 1 Memory Usage: 37kB
-> Subquery Scan on x (cost=9381.66..9438.24 rows=2829 width=48) (actual time=647.409..647.805 rows=55 loops=1)
-> HashAggregate (cost=9381.66..9409.95 rows=2829 width=12) (actual time=647.403..647.786 rows=55 loops=1)
Group Key: pt.user_id
Batches: 1 Memory Usage: 121kB
-> Nested Loop (cost=1.86..9367.51 rows=2829 width=4) (actual time=0.056..625.245 rows=120022 loops=1)
-> Nested Loop (cost=1.44..3692.96 rows=12832 width=8) (actual time=0.047..171.754 rows=217440 loops=1)
-> Nested Loop (cost=1.00..254.63 rows=25 width=12) (actual time=0.030..1.407 rows=56 loops=1)
Join Filter: (u.id = user_stats_1.user_id)
-> Nested Loop (cost=0.71..243.08 rows=25 width=8) (actual time=0.018..1.207 rows=87 loops=1)
-> Index Scan using index_users_on_last_seen_at on users u (cost=0.42..86.71 rows=27 width=4) (actual time=0.009..0.156 rows=87 loops=1)
Index Cond: (last_seen_at > '2023-04-11 00:47:07.437568'::timestamp without time zone)
-> Index Only Scan using user_stats_pkey on user_stats us (cost=0.29..5.79 rows=1 width=4) (actual time=0.011..0.011 rows=1 loops=87)
Index Cond: (user_id = u.id)
Heap Fetches: 87
-> Index Scan using user_stats_pkey on user_stats user_stats_1 (cost=0.29..0.45 rows=1 width=4) (actual time=0.002..0.002 rows=1 loops=87)
Index Cond: (user_id = us.user_id)
Filter: (posts_read_count < 10000)
Rows Removed by Filter: 0
-> Index Scan using index_post_timings_on_user_id on post_timings pt (cost=0.44..92.98 rows=4455 width=8) (actual time=0.036..2.492 rows=3883 loops=56)
Index Cond: (user_id = user_stats_1.user_id)
-> Index Scan using forum_threads_pkey on topics t (cost=0.42..0.44 rows=1 width=4) (actual time=0.002..0.002 rows=1 loops=217440)
Index Cond: (id = pt.topic_id)
Filter: ((deleted_at IS NULL) AND ((archetype)::text = 'regular'::text))
Rows Removed by Filter: 0
Planning Time: 1.406 ms
Execution Time: 677.817 ms
```