chore: 문서를 작성할 때 한국어의 표현 작성 스킬 추가 및 1인칭 관점의 글 작성 검증 테스트 추가

2026-07-29 16:48:03 +09:00
parent c39406bbdd
commit 41501b5d06
520 changed files with 95494 additions and 2231 deletions
@@ -0,0 +1,27 @@
+-- L16 (b) UNION decompose — 3 visibility branches, each index-ordered, Merge Append + Hash Join
+-- FeedVisibilityIT.l16ExplainThreeWayPlanCompare (seed 2000, viewer user008)
+-- (public branch) UNION ALL (mentioned branch: JOIN feed_item_mentions) UNION ALL (private branch: partial idx)
+--   ORDER BY first_highlighted_at DESC, id DESC LIMIT 20
+-- 읽기 포인트: Merge Append 가 미리 정렬된 분기 스트림을 병합(전체 재정렬 없음). 멘션 EXISTS 가 Hash Join(집합 기반)
+--            으로, private 는 Index Only Scan(partial)+Incremental Sort 로. 구조는 우수하나 buffers 200(분기별 스캔).
+
+Limit  (cost=97.16..97.40 rows=13 width=24) (actual time=0.655..0.661 rows=20 loops=1)
+  Buffers: shared hit=200
+  ->  Merge Append  (cost=97.16..97.40 rows=13 width=24) (actual time=0.654..0.659 rows=20 loops=1)
+        Sort Key: fi.first_highlighted_at DESC, fi.id DESC
+        Buffers: shared hit=200
+        ->  Limit (rows=17)          -- public branch
+              ->  Sort (top-N heapsort)
+                    ->  Bitmap Heap Scan on feed_items fi  (Recheck Cond: visibility='PUBLIC')
+                          ->  Bitmap Index Scan on ix_feed_items_visibility_sort
+        ->  Limit (rows=3)           -- mentioned branch: EXISTS -> Hash Join
+              ->  Sort (top-N heapsort)
+                    ->  Hash Join  (Hash Cond: fi_1.id = m.feed_item_id)
+                          ->  Bitmap Heap Scan on feed_items fi_1 (visibility='MENTIONED')
+                          ->  Hash -> Bitmap Heap Scan on feed_item_mentions m
+                                ->  Bitmap Index Scan on ix_mentions_user (mentioned_user_id=:me)
+        ->  Limit (rows=2)           -- private branch: partial index, index-only
+              ->  Incremental Sort  (Presorted Key: fi_2.first_highlighted_at)
+                    ->  Index Only Scan using ix_feed_items_private on feed_items fi_2 (user_id=:me)  Heap Fetches: 21
+Planning Time: 0.398 ms
+Execution Time: 0.780 ms