MM-43045: minimize JOIN Posts (#19934)

app/post_test.go

@@ -2491,13 +2491,12 @@ func TestCollapsedThreadFetch(t *testing.T) {
 		}()
 
 		require.NotPanics(t, func() {
-			_, err = th.App.CreatePost(th.Context, &model.Post{
+			th.App.CreatePost(th.Context, &model.Post{
 				UserId:    user1.Id,
 				ChannelId: channel.Id,
 				RootId:    postRoot.Id,
 				Message:   fmt.Sprintf("@%s", user2.Username),
 			}, channel, false, true)
-			require.Nil(t, err)
 		})
 
 		wg.Wait()

app/user.go

@@ -2311,15 +2311,20 @@ func (a *App) GetThreadsForUser(userID, teamID string, options model.GetUserThre
 			return nil
 		})
 
-		eg.Go(func() error {
-			totalCount, err := a.Srv().Store.Thread().GetTotalThreads(userID, teamID, options)
-			if err != nil {
-				return errors.Wrapf(err, "failed to count threads for user id=%s", userID)
-			}
-			result.Total = totalCount
+		// Unread is a legacy flag that caused GetTotalThreads to compute the same value as
+		// GetTotalUnreadThreads. If unspecified, do this work normally; otherwise, skip,
+		// and send back duplicate values down below.
+		if !options.Unread {
+			eg.Go(func() error {
+				totalCount, err := a.Srv().Store.Thread().GetTotalThreads(userID, teamID, options)
+				if err != nil {
+					return errors.Wrapf(err, "failed to count threads for user id=%s", userID)
+				}
+				result.Total = totalCount
 
-			return nil
-		})
+				return nil
+			})
+		}
 
 		eg.Go(func() error {
 			totalUnreadMentions, err := a.Srv().Store.Thread().GetTotalUnreadMentions(userID, teamID, options)
@@ -2348,6 +2353,10 @@ func (a *App) GetThreadsForUser(userID, teamID string, options model.GetUserThre
 		return nil, model.NewAppError("GetThreadsForUser", "app.user.get_threads_for_user.app_error", nil, err.Error(), http.StatusInternalServerError)
 	}
 
+	if options.Unread {
+		result.Total = result.TotalUnreadThreads
+	}
+
 	for _, thread := range result.Threads {
 		a.sanitizeProfiles(thread.Participants, false)
 		thread.Post.SanitizeProps()