Merge pull request #227 from prgrms-web-devcourse-final-project/jsy/indexing

♻️ refactor: event_members 테이블에 (event_id, member_id) 복합 인덱스 추가

Author: yoozafree

src/main/resources/indexing_mysql.sql

@@ -0,0 +1,29 @@
+-- 1. 인덱스 생성
+CREATE INDEX idx_event_members_event_member
+    ON event_members(event_id, member_id);
+
+# CREATE INDEX idx_event_members_event_activated
+#     ON event_members(event_id, confirmed);
+
+-- 2. 인덱스 확인 (MySQL에서는 SHOW INDEX 사용)
+SHOW INDEX FROM event_members;
+
+-- 3. 쿼리 성능 계획 확인
+EXPLAIN
+SELECT *
+FROM event_members
+WHERE event_id = 1
+  AND member_id = 'GOOGLE_115434652372556552718'
+    LIMIT 1;
+
+-- mysql 은 전체 강제 인덱싱 사용 옵션이 따로 없음.
+
+-- FORCE INDEX로 인덱스 유도 가능
+EXPLAIN
+SELECT *
+FROM event_members FORCE INDEX (idx_event_members_event_member)
+WHERE event_id = 1 AND member_id = 'GOOGLE_115434652372556552718'
+    LIMIT 1;
+
+
+SHOW INDEX FROM event_members;

src/main/resources/indexing_postgres.sql

@@ -0,0 +1,30 @@
+-- 1. 인덱스 생성
+CREATE INDEX IF NOT EXISTS idx_event_members_event_member
+    ON event_members(event_id, member_id);
+
+-- CREATE INDEX IF NOT EXISTS idx_event_members_event_activated
+--     ON event_members(event_id, confirmed);
+
+-- 2. 인덱스 확인 (스키마 명시)
+SELECT *
+FROM pg_catalog.pg_indexes
+WHERE tablename = 'event_members';
+
+-- 3. 쿼리 성능 계획 확인
+EXPLAIN
+SELECT *
+FROM event_members
+WHERE event_id = 1
+  AND member_id = 'GOOGLE_115434652372556552718'
+LIMIT 1;
+
+-- 실제 쿼리에 인덱스 사용되는지 확인. 지금 row 1개라 자동으로 seq scan(full scan)
+EXPLAIN ANALYZE
+SELECT *
+FROM event_members
+WHERE event_id = 1
+  AND member_id = 'GOOGLE_115434652372556552718'
+LIMIT 1;
+
+-- 강제 인덱스 사용 유도
+SET enable_seqscan = OFF;