-- Crown Task 4 — deep-page keyset on the single-OR parent path (re-resolves visibility every page)
-- FeedCrownIT.crownDeepPageKeysetSeeksFewerRowsWithPrecomputeThanSingleOr (seed 2000, user008, deepest page)
-- 읽기 포인트: 단일 OR 부모선택은 사전계산 읽기 모델(ix_feed_visible)을 못 쓴다(구조적). 매 페이지 가시성
--   3분기를 BitmapOr 로 다시 풀고(public/mentioned = ix_feed_items_visibility_sort, private = ix_feed_items_private),
--   멘션 EXISTS 는 hashed SubPlan 2 로 user008 의 멘션 200행을 materialize 한다 → 훑는 행수 200(사전계산 19 대비).
--   커서는 세 분기 Index Cond 에 ROW(...) < ROW(cursor) 로 들어가 seek 은 하나, 페이지마다 전체 가시성을 재계산한다.

Nested Loop  (cost=94.10..163.18 rows=15 width=686) (actual time=0.128..0.161 rows=19 loops=1)
  Buffers: shared hit=88
  ->  Limit  (cost=93.82..93.83 rows=5 width=24) (actual time=0.118..0.120 rows=19 loops=1)
        Buffers: shared hit=31
        ->  Sort  (cost=93.82..93.83 rows=5 width=24) (actual time=0.117..0.119 rows=19 loops=1)
              Sort Key: fi.first_highlighted_at DESC, fi.id DESC
              Sort Method: quicksort  Memory: 26kB
              Buffers: shared hit=31
              ->  Bitmap Heap Scan on feed_items fi  (cost=12.90..93.76 rows=5 width=24) (actual time=0.027..0.112 rows=19 loops=1)
                    Recheck Cond: ((((visibility)::text = 'PUBLIC'::text) AND (ROW(first_highlighted_at, id) < ROW('2026-04-17 21:00:00+00'::timestamp with time zone, '759efcc1-efd0-4a24-94d6-7e83001fabb1'::uuid))) OR (((visibility)::text = 'MENTIONED'::text) AND (ROW(first_highlighted_at, id) < ROW('2026-04-17 21:00:00+00'::timestamp with time zone, '759efcc1-efd0-4a24-94d6-7e83001fabb1'::uuid))) OR ((user_id = 'e6a2f6da-c975-41ef-9b48-a4a6c1a72cc0'::uuid) AND (ROW(first_highlighted_at, id) < ROW('2026-04-17 21:00:00+00'::timestamp with time zone, '759efcc1-efd0-4a24-94d6-7e83001fabb1'::uuid)) AND ((visibility)::text = 'PRIVATE'::text)))
                    Filter: (((visibility)::text = 'PUBLIC'::text) OR (((visibility)::text = 'MENTIONED'::text) AND (hashed SubPlan 2)) OR (((visibility)::text = 'PRIVATE'::text) AND (user_id = 'e6a2f6da-c975-41ef-9b48-a4a6c1a72cc0'::uuid)))
                    Rows Removed by Filter: 4
                    Heap Blocks: exact=6
                    Buffers: shared hit=31
                    ->  BitmapOr  (cost=12.90..12.90 rows=7 width=0) (actual time=0.019..0.019 rows=0 loops=1)
                          Buffers: shared hit=6
                          ->  Bitmap Index Scan on ix_feed_items_visibility_sort  (cost=0.00..4.31 rows=3 width=0) (actual time=0.013..0.014 rows=48 loops=1)
                                Index Cond: (((visibility)::text = 'PUBLIC'::text) AND (ROW(first_highlighted_at, id) < ROW('2026-04-17 21:00:00+00'::timestamp with time zone, '759efcc1-efd0-4a24-94d6-7e83001fabb1'::uuid)))
                                Buffers: shared hit=2
                          ->  Bitmap Index Scan on ix_feed_items_visibility_sort  (cost=0.00..4.31 rows=3 width=0) (actual time=0.003..0.003 rows=18 loops=1)
                                Index Cond: (((visibility)::text = 'MENTIONED'::text) AND (ROW(first_highlighted_at, id) < ROW('2026-04-17 21:00:00+00'::timestamp with time zone, '759efcc1-efd0-4a24-94d6-7e83001fabb1'::uuid)))
                                Buffers: shared hit=2
                          ->  Bitmap Index Scan on ix_feed_items_private  (cost=0.00..4.28 rows=1 width=0) (actual time=0.001..0.001 rows=1 loops=1)
                                Index Cond: ((user_id = 'e6a2f6da-c975-41ef-9b48-a4a6c1a72cc0'::uuid) AND (ROW(first_highlighted_at, id) < ROW('2026-04-17 21:00:00+00'::timestamp with time zone, '759efcc1-efd0-4a24-94d6-7e83001fabb1'::uuid)))
                                Buffers: shared hit=2
                    SubPlan 2
                      ->  Bitmap Heap Scan on feed_item_mentions m  (cost=4.33..24.04 rows=7 width=16) (actual time=0.014..0.038 rows=200 loops=1)
                            Recheck Cond: (mentioned_user_id = 'e6a2f6da-c975-41ef-9b48-a4a6c1a72cc0'::uuid)
                            Heap Blocks: exact=16
                            Buffers: shared hit=19
                            ->  Bitmap Index Scan on ix_mentions_user  (cost=0.00..4.33 rows=7 width=0) (actual time=0.011..0.011 rows=200 loops=1)
                                  Index Cond: (mentioned_user_id = 'e6a2f6da-c975-41ef-9b48-a4a6c1a72cc0'::uuid)
                                  Buffers: shared hit=3
  ->  Limit  (cost=0.28..13.83 rows=3 width=670) (actual time=0.002..0.002 rows=1 loops=19)
        Buffers: shared hit=57
        ->  Index Scan using ix_highlights_feed_items_created on highlights h  (cost=0.28..36.42 rows=8 width=670) (actual time=0.002..0.002 rows=1 loops=19)
              Index Cond: (feed_item_id = fi.id)
              Buffers: shared hit=57
Planning Time: 0.153 ms
Execution Time: 0.250 ms