Add Index to `comment.dependent_issue_id` (#27325) (#27340)

Backport #27325 by @JakobDev

This Column is missing index. It is used by
[issue_service.deleteIssue](7ea2a910ce/services/issue/issue.go (L300)).

Co-authored-by: JakobDev <jakobdev@gmx.de>

models/issues/comment.go

@@ -246,7 +246,7 @@ type Comment struct {
 	NewTitle         string
 	OldRef           string
 	NewRef           string
-	DependentIssueID int64
+	DependentIssueID int64  `xorm:"index"` // This is used by issue_service.deleteIssue
 	DependentIssue   *Issue `xorm:"-"`
 
 	CommitID        int64

models/migrations/migrations.go

@@ -536,6 +536,8 @@ var migrations = []Migration{
 	NewMigration("Add RemoteAddress to mirrors", v1_21.AddRemoteAddressToMirrors),
 	// v277 -> v278
 	NewMigration("Add Index to issue_user.issue_id", v1_21.AddIndexToIssueUserIssueID),
+	// v278 -> v279
+	NewMigration("Add Index to comment.dependent_issue_id", v1_21.AddIndexToCommentDependentIssueID),
 }
 
 // GetCurrentDBVersion returns the current db version

models/migrations/v1_21/v278.go

@@ -0,0 +1,16 @@
+// Copyright 2023 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package v1_21 //nolint
+
+import (
+	"xorm.io/xorm"
+)
+
+func AddIndexToCommentDependentIssueID(x *xorm.Engine) error {
+	type Comment struct {
+		DependentIssueID int64 `xorm:"index"`
+	}
+
+	return x.Sync(new(Comment))
+}