Pager usage is off.
                                         version                                         
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 PostgreSQL 18.6 on x86_64-pc-linux-musl, compiled by gcc (Alpine 15.2.0) 15.2.0, 64-bit
(1 row)

DROP SCHEMA
CREATE SCHEMA
SET
 setseed 
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(1 row)

CREATE TABLE
INSERT 0 1000000
CREATE INDEX
VACUUM
BASELINE: WARMUP
                                                                     QUERY PLAN                                                                     
----------------------------------------------------------------------------------------------------------------------------------------------------
 Limit  (cost=9193.98..9194.00 rows=10 width=35) (actual time=9.855..9.858 rows=10.00 loops=1)
   Buffers: shared hit=8333 read=11
   ->  Sort  (cost=9193.98..9218.31 rows=9733 width=35) (actual time=9.853..9.855 rows=10.00 loops=1)
         Sort Key: created_at DESC
         Sort Method: top-N heapsort  Memory: 25kB
         Buffers: shared hit=8333 read=11
         ->  Bitmap Heap Scan on comments  (cost=111.86..8983.65 rows=9733 width=35) (actual time=2.353..9.133 rows=10000.00 loops=1)
               Recheck Cond: (user_id = 42)
               Heap Blocks: exact=8333
               Buffers: shared hit=8333 read=11
               ->  Bitmap Index Scan on ix_comments_user_id  (cost=0.00..109.42 rows=9733 width=0) (actual time=1.395..1.396 rows=10000.00 loops=1)
                     Index Cond: (user_id = 42)
                     Index Searches: 1
                     Buffers: shared read=11
 Planning:
   Buffers: shared hit=40 read=3
 Planning Time: 0.519 ms
 Execution Time: 10.084 ms
(18 rows)

BASELINE: MEASURED
                                                                     QUERY PLAN                                                                     
----------------------------------------------------------------------------------------------------------------------------------------------------
 Limit  (cost=9193.98..9194.00 rows=10 width=35) (actual time=16.326..16.329 rows=10.00 loops=1)
   Buffers: shared hit=8344
   ->  Sort  (cost=9193.98..9218.31 rows=9733 width=35) (actual time=16.324..16.325 rows=10.00 loops=1)
         Sort Key: created_at DESC
         Sort Method: top-N heapsort  Memory: 25kB
         Buffers: shared hit=8344
         ->  Bitmap Heap Scan on comments  (cost=111.86..8983.65 rows=9733 width=35) (actual time=2.206..13.236 rows=10000.00 loops=1)
               Recheck Cond: (user_id = 42)
               Heap Blocks: exact=8333
               Buffers: shared hit=8344
               ->  Bitmap Index Scan on ix_comments_user_id  (cost=0.00..109.42 rows=9733 width=0) (actual time=1.376..1.376 rows=10000.00 loops=1)
                     Index Cond: (user_id = 42)
                     Index Searches: 1
                     Buffers: shared hit=11
 Planning Time: 0.118 ms
 Execution Time: 16.537 ms
(16 rows)

CREATE INDEX
DATE INDEX: WARMUP
                                                                      QUERY PLAN                                                                       
-------------------------------------------------------------------------------------------------------------------------------------------------------
 Limit  (cost=0.42..63.93 rows=10 width=35) (actual time=240.240..240.278 rows=10.00 loops=1)
   Buffers: shared hit=495902 read=1358
   ->  Index Scan using ix_comments_created_at on comments  (cost=0.42..61814.32 rows=9733 width=35) (actual time=240.238..240.274 rows=10.00 loops=1)
         Filter: (user_id = 42)
         Rows Removed by Filter: 495944
         Index Searches: 1
         Buffers: shared hit=495902 read=1358
 Planning:
   Buffers: shared hit=17 read=1
 Planning Time: 0.279 ms
 Execution Time: 240.306 ms
(11 rows)

DATE INDEX: MEASURED
                                                                      QUERY PLAN                                                                       
-------------------------------------------------------------------------------------------------------------------------------------------------------
 Limit  (cost=0.42..63.93 rows=10 width=35) (actual time=241.245..241.279 rows=10.00 loops=1)
   Buffers: shared hit=497260
   ->  Index Scan using ix_comments_created_at on comments  (cost=0.42..61814.32 rows=9733 width=35) (actual time=241.243..241.276 rows=10.00 loops=1)
         Filter: (user_id = 42)
         Rows Removed by Filter: 495944
         Index Searches: 1
         Buffers: shared hit=497260
 Planning Time: 0.082 ms
 Execution Time: 241.354 ms
(9 rows)

CREATE INDEX
COMPOSITE INDEX: WARMUP
                                                                    QUERY PLAN                                                                    
--------------------------------------------------------------------------------------------------------------------------------------------------
 Limit  (cost=0.42..26.01 rows=10 width=35) (actual time=0.031..0.043 rows=10.00 loops=1)
   Buffers: shared hit=10 read=3
   ->  Index Scan using ix_comments_user_date on comments  (cost=0.42..24902.26 rows=9733 width=35) (actual time=0.030..0.041 rows=10.00 loops=1)
         Index Cond: (user_id = 42)
         Index Searches: 1
         Buffers: shared hit=10 read=3
 Planning:
   Buffers: shared hit=20 read=1
 Planning Time: 0.267 ms
 Execution Time: 0.058 ms
(10 rows)

COMPOSITE INDEX: MEASURED
                                                                    QUERY PLAN                                                                    
--------------------------------------------------------------------------------------------------------------------------------------------------
 Limit  (cost=0.42..26.01 rows=10 width=35) (actual time=0.032..0.043 rows=10.00 loops=1)
   Buffers: shared hit=13
   ->  Index Scan using ix_comments_user_date on comments  (cost=0.42..24902.26 rows=9733 width=35) (actual time=0.031..0.042 rows=10.00 loops=1)
         Index Cond: (user_id = 42)
         Index Searches: 1
         Buffers: shared hit=13
 Planning Time: 0.084 ms
 Execution Time: 0.067 ms
(8 rows)