Decrease the num_stars when deleting a repo

models/migrations/migrations.go

@@ -218,6 +218,8 @@ var migrations = []Migration{
 	NewMigration("Add KeepActivityPrivate to User table", addKeepActivityPrivateUserColumn),
 	// v142 -> v143
 	NewMigration("Ensure Repository.IsArchived is not null", setIsArchivedToFalse),
+	// v143 -> v144
+	NewMigration("recalculate Stars number for all user", recalculateStars),
 }
 
 // GetCurrentDBVersion returns the current db version

models/migrations/v143.go

@@ -0,0 +1,46 @@
+// Copyright 2020 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package migrations
+
+import (
+	"code.gitea.io/gitea/models"
+	"code.gitea.io/gitea/modules/log"
+	"xorm.io/xorm"
+)
+
+func recalculateStars(x *xorm.Engine) (err error) {
+	// because of issue https://github.com/go-gitea/gitea/issues/11949,
+	// recalculate Stars number for all users to fully fix it.
+
+	const batchSize = 100
+	sess := x.NewSession()
+	defer sess.Close()
+
+	for start := 0; ; start += batchSize {
+		userIDs := make([]int64, 0, batchSize)
+		if err = sess.Table("user").Limit(batchSize, start).Where("type = ?", 0).Cols("id").Find(&userIDs); err != nil {
+			return err
+		}
+		if len(userIDs) == 0 {
+			break
+		}
+
+		var number int64
+
+		for _, uid := range userIDs {
+			if number, err = x.Where("uid = ?", uid).Count(new(models.Star)); err != nil {
+				return
+			}
+
+			if _, err = x.Exec("UPDATE `user` SET num_stars=? WHERE id = ?", number, uid); err != nil {
+				return err
+			}
+		}
+	}
+
+	log.Debug("recalculate Stars number for all user finished")
+
+	return sess.Commit()
+}

models/repo.go

@@ -1586,6 +1586,10 @@ func DeleteRepository(doer *User, uid, repoID int64) error {
 		releaseAttachments = append(releaseAttachments, attachments[i].LocalPath())
 	}
 
+	if _, err = sess.Exec("UPDATE `user` SET num_stars=num_stars-1 WHERE id IN (SELECT `uid` FROM `star` WHERE repo_id = ?)", repo.ID); err != nil {
+		return err
+	}
+
 	if err = deleteBeans(sess,
 		&Access{RepoID: repo.ID},
 		&Action{RepoID: repo.ID},