48 lines
4.9 KiB
Plaintext
Executable File
48 lines
4.9 KiB
Plaintext
Executable File
-- Crown Task 4 — deep-page keyset on the single-OR parent path (re-resolves visibility every page)
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-- FeedCrownIT.crownDeepPageKeysetSeeksFewerRowsWithPrecomputeThanSingleOr (seed 2000, user008, deepest page)
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-- 읽기 포인트: 단일 OR 부모선택은 사전계산 읽기 모델(ix_feed_visible)을 못 쓴다(구조적). 매 페이지 가시성
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-- 3분기를 BitmapOr 로 다시 풀고(public/mentioned = ix_feed_items_visibility_sort, private = ix_feed_items_private),
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-- 멘션 EXISTS 는 hashed SubPlan 2 로 user008 의 멘션 200행을 materialize 한다 → 훑는 행수 200(사전계산 19 대비).
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-- 커서는 세 분기 Index Cond 에 ROW(...) < ROW(cursor) 로 들어가 seek 은 하나, 페이지마다 전체 가시성을 재계산한다.
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Nested Loop (cost=94.10..163.18 rows=15 width=686) (actual time=0.128..0.161 rows=19 loops=1)
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Buffers: shared hit=88
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-> Limit (cost=93.82..93.83 rows=5 width=24) (actual time=0.118..0.120 rows=19 loops=1)
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Buffers: shared hit=31
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-> Sort (cost=93.82..93.83 rows=5 width=24) (actual time=0.117..0.119 rows=19 loops=1)
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Sort Key: fi.first_highlighted_at DESC, fi.id DESC
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Sort Method: quicksort Memory: 26kB
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Buffers: shared hit=31
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-> 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)
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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)))
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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)))
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Rows Removed by Filter: 4
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Heap Blocks: exact=6
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Buffers: shared hit=31
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-> BitmapOr (cost=12.90..12.90 rows=7 width=0) (actual time=0.019..0.019 rows=0 loops=1)
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Buffers: shared hit=6
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-> 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)
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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)))
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Buffers: shared hit=2
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-> 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)
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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)))
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Buffers: shared hit=2
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-> 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)
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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)))
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Buffers: shared hit=2
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SubPlan 2
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-> 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)
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Recheck Cond: (mentioned_user_id = 'e6a2f6da-c975-41ef-9b48-a4a6c1a72cc0'::uuid)
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Heap Blocks: exact=16
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Buffers: shared hit=19
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-> 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)
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Index Cond: (mentioned_user_id = 'e6a2f6da-c975-41ef-9b48-a4a6c1a72cc0'::uuid)
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Buffers: shared hit=3
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-> Limit (cost=0.28..13.83 rows=3 width=670) (actual time=0.002..0.002 rows=1 loops=19)
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Buffers: shared hit=57
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-> 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)
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Index Cond: (feed_item_id = fi.id)
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Buffers: shared hit=57
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Planning Time: 0.153 ms
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Execution Time: 0.250 ms
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