From 4f7f91773a870eb555df7acfc09ab2bb67be95c7 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=EB=82=98=EB=AF=B8?= <dnska6657@gmail.com>
Date: Wed, 12 Aug 2026 17:24:56 +0900
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PostgreSQL은 MySQL(InnoDB)과 달리 FK 컬럼을 자동으로 인덱싱하지 않는다.
course/record/user_stamp/scrap/heart_rate_sample의 FK 컬럼에 인덱스가
없어 관련 조회가 Seq Scan으로 처리되고 있었다.

EXPLAIN (ANALYZE, BUFFERS)로 30만 건 규모 합성 데이터에서 실측:
- course.user_id: 52.516ms → 3.258ms (Seq Scan → Bitmap Heap Scan)
- record.user_id: 11.081ms → 2.704ms (Parallel Seq Scan → Bitmap Heap Scan)
- user_stamp.user_id: 15.984ms → 1.835ms (Seq Scan → Index Scan)
- scrap.public_course_id: 3.696ms → 1.233ms (Seq Scan → Bitmap Heap Scan)
- heart_rate_sample.record_health_data_id: 8.507ms → 0.429ms (Parallel Seq Scan → Bitmap Heap Scan)
---
 src/main/java/org/runnect/server/course/entity/Course.java   | 3 +++
 .../org/runnect/server/health/entity/HeartRateSample.java    | 5 +++++
 src/main/java/org/runnect/server/record/entity/Record.java   | 5 +++++
 src/main/java/org/runnect/server/scrap/entity/Scrap.java     | 2 ++
 src/main/java/org/runnect/server/user/entity/UserStamp.java  | 3 +++
 5 files changed, 18 insertions(+)

diff --git a/src/main/java/org/runnect/server/course/entity/Course.java b/src/main/java/org/runnect/server/course/entity/Course.java
index 82a8b07..6055150 100644
--- a/src/main/java/org/runnect/server/course/entity/Course.java
+++ b/src/main/java/org/runnect/server/course/entity/Course.java
@@ -16,6 +16,9 @@
 
 @Getter
 @Entity
+@Table(indexes = {
+    @Index(name = "idx_course_user_id", columnList = "user_id")
+})
 @NoArgsConstructor(access = AccessLevel.PROTECTED)
 public class Course extends AuditingTimeEntity {
 
diff --git a/src/main/java/org/runnect/server/health/entity/HeartRateSample.java b/src/main/java/org/runnect/server/health/entity/HeartRateSample.java
index ffbef46..6d8ade3 100644
--- a/src/main/java/org/runnect/server/health/entity/HeartRateSample.java
+++ b/src/main/java/org/runnect/server/health/entity/HeartRateSample.java
@@ -6,8 +6,10 @@
 import javax.persistence.GeneratedValue;
 import javax.persistence.GenerationType;
 import javax.persistence.Id;
+import javax.persistence.Index;
 import javax.persistence.JoinColumn;
 import javax.persistence.ManyToOne;
+import javax.persistence.Table;
 import lombok.AccessLevel;
 import lombok.Builder;
 import lombok.Getter;
@@ -16,6 +18,9 @@
 
 @Getter
 @Entity
+@Table(indexes = {
+    @Index(name = "idx_heart_rate_sample_record_health_data_id", columnList = "record_health_data_id")
+})
 @NoArgsConstructor(access = AccessLevel.PROTECTED)
 public class HeartRateSample extends AuditingTimeEntity {
 
diff --git a/src/main/java/org/runnect/server/record/entity/Record.java b/src/main/java/org/runnect/server/record/entity/Record.java
index d82f88d..3b156b0 100644
--- a/src/main/java/org/runnect/server/record/entity/Record.java
+++ b/src/main/java/org/runnect/server/record/entity/Record.java
@@ -7,8 +7,10 @@
 import javax.persistence.GeneratedValue;
 import javax.persistence.GenerationType;
 import javax.persistence.Id;
+import javax.persistence.Index;
 import javax.persistence.JoinColumn;
 import javax.persistence.ManyToOne;
+import javax.persistence.Table;
 import lombok.AccessLevel;
 import lombok.Builder;
 import lombok.Getter;
@@ -20,6 +22,9 @@
 
 @Getter
 @Entity
+@Table(indexes = {
+    @Index(name = "idx_record_user_id", columnList = "user_id")
+})
 @NoArgsConstructor(access = AccessLevel.PROTECTED)
 public class Record extends AuditingTimeEntity {
 
diff --git a/src/main/java/org/runnect/server/scrap/entity/Scrap.java b/src/main/java/org/runnect/server/scrap/entity/Scrap.java
index f464001..416f3f1 100644
--- a/src/main/java/org/runnect/server/scrap/entity/Scrap.java
+++ b/src/main/java/org/runnect/server/scrap/entity/Scrap.java
@@ -18,6 +18,8 @@
         @UniqueConstraint(
                 columnNames = {"user_id", "public_course_id"}
         )
+}, indexes = {
+        @Index(name = "idx_scrap_public_course_id", columnList = "public_course_id")
 })
 @DynamicUpdate
 public class Scrap extends AuditingTimeEntity {
diff --git a/src/main/java/org/runnect/server/user/entity/UserStamp.java b/src/main/java/org/runnect/server/user/entity/UserStamp.java
index feaec49..81a653b 100644
--- a/src/main/java/org/runnect/server/user/entity/UserStamp.java
+++ b/src/main/java/org/runnect/server/user/entity/UserStamp.java
@@ -10,6 +10,9 @@
 
 @Getter
 @Entity
+@Table(indexes = {
+    @Index(name = "idx_user_stamp_user_id", columnList = "user_id")
+})
 @NoArgsConstructor(access = AccessLevel.PROTECTED)
 public class UserStamp extends AuditingTimeEntity {