Add combined index for issue_user.uid and issue_id

fixes go-gitea#27877

models/issues/issue_user.go

@@ -14,8 +14,8 @@ import (
 // IssueUser represents an issue-user relation.
 type IssueUser struct {
 	ID          int64 `xorm:"pk autoincr"`
-	UID         int64 `xorm:"INDEX"` // User ID.
-	IssueID     int64 `xorm:"INDEX"`
+	UID         int64 `xorm:"INDEX INDEX(uidtoissue)"` // User ID.
+	IssueID     int64 `xorm:"INDEX INDEX(uidtoissue)"`
 	IsRead      bool
 	IsMentioned bool
 }

models/migrations/migrations.go

@@ -550,6 +550,8 @@ var migrations = []Migration{
 	NewMigration("Add auth_token table", v1_22.CreateAuthTokenTable),
 	// v282 -> v283
 	NewMigration("Add Index to pull_auto_merge.doer_id", v1_22.AddIndexToPullAutoMergeDoerID),
+	// v283 -> v284
+	NewMigration("Add combined Index to issue_user.uid and issue_id", v1_22.AddCombinedIndexToIssueUser),
 }
 
 // GetCurrentDBVersion returns the current db version

models/migrations/v1_22/v283.go

@@ -0,0 +1,17 @@
+// Copyright 2023 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package v1_22 //nolint
+
+import (
+	"xorm.io/xorm"
+)
+
+func AddCombinedIndexToIssueUser(x *xorm.Engine) error {
+	type IssueUser struct {
+		UID     int64 `xorm:"INDEX(uidtoissue)"` // User ID.
+		IssueID int64 `xorm:"INDEX(uidtoissue)"`
+	}
+
+	return x.Sync(&IssueUser{})
+}