diff --git a/services/statistics-service/deploy/mysql/initdb/001_statistics_service.sql b/services/statistics-service/deploy/mysql/initdb/001_statistics_service.sql
index 0a7704ad..591b8f1d 100644
--- a/services/statistics-service/deploy/mysql/initdb/001_statistics_service.sql
+++ b/services/statistics-service/deploy/mysql/initdb/001_statistics_service.sql
@@ -27,6 +27,7 @@ CREATE TABLE IF NOT EXISTS app_tracking_events (
   target_id VARCHAR(128) NOT NULL DEFAULT '' COMMENT '目标 ID',
   user_id BIGINT NOT NULL DEFAULT 0 COMMENT '服务端识别的用户 ID，匿名为 0',
   device_id VARCHAR(128) NOT NULL DEFAULT '' COMMENT '设备 ID',
+  identity_key VARCHAR(160) GENERATED ALWAYS AS (CASE WHEN user_id > 0 THEN CONCAT('u:', user_id) ELSE CONCAT('d:', device_id) END) VIRTUAL COMMENT '漏斗/留存去重身份，登录用户优先 user_id，匿名用户回退 device_id',
   session_id VARCHAR(160) NOT NULL DEFAULT '' COMMENT '会话 ID',
   platform VARCHAR(32) NOT NULL DEFAULT '' COMMENT '平台',
   app_version VARCHAR(64) NOT NULL DEFAULT '' COMMENT 'App 版本',
@@ -45,7 +46,9 @@ CREATE TABLE IF NOT EXISTS app_tracking_events (
   KEY idx_app_tracking_event_name (app_code, stat_day, event_name),
   KEY idx_app_tracking_screen (app_code, stat_day, screen),
   KEY idx_app_tracking_user (app_code, user_id, occurred_at_ms),
-  KEY idx_app_tracking_device (app_code, device_id, occurred_at_ms)
+  KEY idx_app_tracking_device (app_code, device_id, occurred_at_ms),
+  KEY idx_app_tracking_event_window (app_code, event_name, occurred_at_ms, identity_key, device_id),
+  KEY idx_app_tracking_retention_identity (app_code, stat_day, identity_key)
 ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci COMMENT='App 埋点原始明细表';
 
 CREATE TABLE IF NOT EXISTS stat_app_day_country (
diff --git a/services/statistics-service/internal/storage/mysql/query.go b/services/statistics-service/internal/storage/mysql/query.go
index abc736aa..f91432ee 100644
--- a/services/statistics-service/internal/storage/mysql/query.go
+++ b/services/statistics-service/internal/storage/mysql/query.go
@@ -2438,7 +2438,10 @@ func appTrackingIdentitySQL(alias string) string {
 	if alias != "" {
 		prefix = alias + "."
 	}
-	return "CASE WHEN " + prefix + "user_id > 0 THEN CONCAT('u:', " + prefix + "user_id) ELSE CONCAT('d:', " + prefix + "device_id) END"
+	// identity_key is a generated column indexed by the statistics schema.
+	// Keeping identity derivation out of hot funnel SQL lets MySQL use window
+	// and retention indexes instead of rebuilding CONCAT keys for every row.
+	return prefix + "identity_key"
 }
 
 func appTrackingEventNames() []string {
diff --git a/services/statistics-service/internal/storage/mysql/query_test.go b/services/statistics-service/internal/storage/mysql/query_test.go
index d2ce5cab..433f9878 100644
--- a/services/statistics-service/internal/storage/mysql/query_test.go
+++ b/services/statistics-service/internal/storage/mysql/query_test.go
@@ -135,19 +135,19 @@ func TestConsumeAppTrackingEventsStoresRawEventsAndDeduplicates(t *testing.T) {
 	}
 
 	var count int64
-	var statDay, screen, propertiesJSON string
+	var statDay, screen, identityKey, propertiesJSON string
 	var userID, countryID, regionID, durationMS int64
 	var success bool
 	if err := repository.db.QueryRowContext(ctx, `
-		SELECT COUNT(*), MAX(CAST(stat_day AS CHAR)), MAX(screen), MAX(user_id), MAX(country_id), MAX(region_id),
+		SELECT COUNT(*), MAX(CAST(stat_day AS CHAR)), MAX(screen), MAX(identity_key), MAX(user_id), MAX(country_id), MAX(region_id),
 		       MAX(duration_ms), MAX(success), COALESCE(MAX(CAST(properties_json AS CHAR)), '{}')
 		FROM app_tracking_events
 		WHERE app_code = 'lalu' AND event_id = 'evt-banner-1'
-	`).Scan(&count, &statDay, &screen, &userID, &countryID, &regionID, &durationMS, &success, &propertiesJSON); err != nil {
+	`).Scan(&count, &statDay, &screen, &identityKey, &userID, &countryID, &regionID, &durationMS, &success, &propertiesJSON); err != nil {
 		t.Fatalf("query app tracking event: %v", err)
 	}
-	if count != 1 || statDay != "2026-07-02" || screen != "home" || userID != 42 || countryID != 86 || regionID != 210 || durationMS != 12 || !success {
-		t.Fatalf("stored event mismatch: count=%d statDay=%s screen=%s userID=%d countryID=%d regionID=%d durationMS=%d success=%v", count, statDay, screen, userID, countryID, regionID, durationMS, success)
+	if count != 1 || statDay != "2026-07-02" || screen != "home" || identityKey != "u:42" || userID != 42 || countryID != 86 || regionID != 210 || durationMS != 12 || !success {
+		t.Fatalf("stored event mismatch: count=%d statDay=%s screen=%s identityKey=%s userID=%d countryID=%d regionID=%d durationMS=%d success=%v", count, statDay, screen, identityKey, userID, countryID, regionID, durationMS, success)
 	}
 	if DecodeJSON(propertiesJSON)["slot"] != "top" {
 		t.Fatalf("properties_json mismatch: %s", propertiesJSON)
diff --git a/services/statistics-service/internal/storage/mysql/repository.go b/services/statistics-service/internal/storage/mysql/repository.go
index 18fa7d96..bd8e1ce3 100644
--- a/services/statistics-service/internal/storage/mysql/repository.go
+++ b/services/statistics-service/internal/storage/mysql/repository.go
@@ -125,6 +125,7 @@ func (r *Repository) Migrate(ctx context.Context) error {
 		  event_type VARCHAR(64) NOT NULL DEFAULT '', screen VARCHAR(128) NOT NULL DEFAULT '',
 		  target_type VARCHAR(64) NOT NULL DEFAULT '', target_id VARCHAR(128) NOT NULL DEFAULT '',
 		  user_id BIGINT NOT NULL DEFAULT 0, device_id VARCHAR(128) NOT NULL DEFAULT '',
+		  identity_key VARCHAR(160) GENERATED ALWAYS AS (CASE WHEN user_id > 0 THEN CONCAT('u:', user_id) ELSE CONCAT('d:', device_id) END) VIRTUAL,
 		  session_id VARCHAR(160) NOT NULL DEFAULT '', platform VARCHAR(32) NOT NULL DEFAULT '',
 		  app_version VARCHAR(64) NOT NULL DEFAULT '', language VARCHAR(32) NOT NULL DEFAULT '',
 		  timezone VARCHAR(64) NOT NULL DEFAULT '', country_id BIGINT NOT NULL DEFAULT 0,
@@ -136,7 +137,9 @@ func (r *Repository) Migrate(ctx context.Context) error {
 		  KEY idx_app_tracking_event_name (app_code, stat_day, event_name),
 		  KEY idx_app_tracking_screen (app_code, stat_day, screen),
 		  KEY idx_app_tracking_user (app_code, user_id, occurred_at_ms),
-		  KEY idx_app_tracking_device (app_code, device_id, occurred_at_ms)
+		  KEY idx_app_tracking_device (app_code, device_id, occurred_at_ms),
+		  KEY idx_app_tracking_event_window (app_code, event_name, occurred_at_ms, identity_key, device_id),
+		  KEY idx_app_tracking_retention_identity (app_code, stat_day, identity_key)
 		) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci`,
 		`CREATE TABLE IF NOT EXISTS stat_app_day_country (
 		  app_code VARCHAR(32) NOT NULL, stat_tz VARCHAR(64) NOT NULL DEFAULT 'UTC', stat_day DATE NOT NULL, country_id BIGINT NOT NULL DEFAULT 0,
@@ -377,6 +380,7 @@ func (r *Repository) Migrate(ctx context.Context) error {
 		}
 	}
 	alterStatements := []string{
+		`ALTER TABLE app_tracking_events ADD COLUMN identity_key VARCHAR(160) GENERATED ALWAYS AS (CASE WHEN user_id > 0 THEN CONCAT('u:', user_id) ELSE CONCAT('d:', device_id) END) VIRTUAL AFTER device_id`,
 		`ALTER TABLE stat_app_day_country ADD COLUMN paid_users BIGINT NOT NULL DEFAULT 0 AFTER active_users`,
 		`ALTER TABLE stat_app_day_country ADD COLUMN game_refund BIGINT NOT NULL DEFAULT 0 AFTER game_payout`,
 		`ALTER TABLE stat_app_day_country ADD COLUMN lucky_gift_payout BIGINT NOT NULL DEFAULT 0 AFTER lucky_gift_turnover`,
@@ -451,6 +455,8 @@ func (r *Repository) Migrate(ctx context.Context) error {
 		{"app_tracking_events", "idx_app_tracking_screen", []string{"app_code", "stat_day", "screen"}},
 		{"app_tracking_events", "idx_app_tracking_user", []string{"app_code", "user_id", "occurred_at_ms"}},
 		{"app_tracking_events", "idx_app_tracking_device", []string{"app_code", "device_id", "occurred_at_ms"}},
+		{"app_tracking_events", "idx_app_tracking_event_window", []string{"app_code", "event_name", "occurred_at_ms", "identity_key", "device_id"}},
+		{"app_tracking_events", "idx_app_tracking_retention_identity", []string{"app_code", "stat_day", "identity_key"}},
 		{"stat_app_day_country", "idx_stat_app_day_region", []string{"app_code", "stat_tz", "stat_day", "region_id"}},
 		{"stat_user_day_activity", "idx_stat_user_day_country", []string{"app_code", "stat_tz", "stat_day", "country_id"}},
 		{"stat_user_day_activity", "idx_stat_user_day_region", []string{"app_code", "stat_tz", "stat_day", "region_id"}},