MM-55295: Improve DB performance of some (Take 2) (#25865)

* Revert "Revert "MM-55295: Improve DB performance of some APIs (#25318)" (#25852)"

This reverts commit 077221a940.

* Fix the issue

```release-note
NONE
```

* lint fix

```release-note
NONE
```

server/channels/store/storetest/channel_store.go

@@ -110,6 +110,7 @@ func TestChannelStore(t *testing.T, rctx request.CTX, ss store.Store, s SqlStore
 	t.Run("IncrementMentionCount", func(t *testing.T) { testChannelStoreIncrementMentionCount(t, rctx, ss) })
 	t.Run("UpdateChannelMember", func(t *testing.T) { testUpdateChannelMember(t, rctx, ss) })
 	t.Run("GetMember", func(t *testing.T) { testGetMember(t, rctx, ss) })
+	t.Run("GetMemberLastViewedAt", func(t *testing.T) { testGetMemberLastViewedAt(t, rctx, ss) })
 	t.Run("GetMemberForPost", func(t *testing.T) { testChannelStoreGetMemberForPost(t, rctx, ss) })
 	t.Run("GetMemberCount", func(t *testing.T) { testGetMemberCount(t, rctx, ss) })
 	t.Run("GetMemberCountsByGroup", func(t *testing.T) { testGetMemberCountsByGroup(t, rctx, ss) })
@@ -246,6 +247,10 @@ func testChannelStoreSaveDirectChannel(t *testing.T, rctx request.CTX, ss store.
 	require.NoError(t, nErr)
 	require.Len(t, members, 2, "should have saved 2 members")
 
+	userIDs, nErr := ss.Channel().GetAllChannelMemberIdsByChannelId(o1.Id)
+	require.NoError(t, nErr)
+	require.ElementsMatch(t, []string{u1.Id, u2.Id}, userIDs)
+
 	_, nErr = ss.Channel().SaveDirectChannel(rctx, &o1, &m1, &m2)
 	require.Error(t, nErr, "shouldn't be a able to update from save")
 
@@ -282,6 +287,10 @@ func testChannelStoreSaveDirectChannel(t *testing.T, rctx request.CTX, ss store.
 	require.NoError(t, nErr)
 	require.Len(t, members, 1, "should have saved just 1 member")
 
+	userIDs, nErr = ss.Channel().GetAllChannelMemberIdsByChannelId(o1.Id)
+	require.NoError(t, nErr)
+	require.ElementsMatch(t, []string{u1.Id}, userIDs)
+
 	// Manually truncate Channels table until testlib can handle cleanups
 	s.GetMasterX().Exec("TRUNCATE Channels")
 }
@@ -4892,6 +4901,62 @@ func testGetMember(t *testing.T, rctx request.CTX, ss store.Store) {
 	ss.Channel().InvalidateCacheForChannelMembersNotifyProps(c2.Id)
 }
 
+func testGetMemberLastViewedAt(t *testing.T, rctx request.CTX, ss store.Store) {
+	userId := model.NewId()
+
+	c1 := &model.Channel{
+		TeamId:      model.NewId(),
+		DisplayName: model.NewId(),
+		Name:        model.NewId(),
+		Type:        model.ChannelTypeOpen,
+	}
+	_, nErr := ss.Channel().Save(c1, -1)
+	require.NoError(t, nErr)
+
+	c2 := &model.Channel{
+		TeamId:      c1.TeamId,
+		DisplayName: model.NewId(),
+		Name:        model.NewId(),
+		Type:        model.ChannelTypeOpen,
+	}
+	_, nErr = ss.Channel().Save(c2, -1)
+	require.NoError(t, nErr)
+
+	m1 := &model.ChannelMember{
+		ChannelId:    c1.Id,
+		UserId:       userId,
+		NotifyProps:  model.GetDefaultChannelNotifyProps(),
+		LastViewedAt: int64(100),
+	}
+	_, err := ss.Channel().SaveMember(m1)
+	require.NoError(t, err)
+
+	m2 := &model.ChannelMember{
+		ChannelId:    c2.Id,
+		UserId:       userId,
+		NotifyProps:  model.GetDefaultChannelNotifyProps(),
+		LastViewedAt: int64(200),
+	}
+	_, err = ss.Channel().SaveMember(m2)
+	require.NoError(t, err)
+
+	_, err = ss.Channel().GetMemberLastViewedAt(context.Background(), model.NewId(), userId)
+	require.Error(t, err, "should've failed to get member for non-existent channel")
+
+	_, err = ss.Channel().GetMemberLastViewedAt(context.Background(), c1.Id, model.NewId())
+	require.Error(t, err, "should've failed to get member for non-existent user")
+
+	lvAt, err := ss.Channel().GetMemberLastViewedAt(context.Background(), c1.Id, userId)
+	require.NoError(t, err, "shouldn't have errored when getting member", err)
+	require.Equal(t, m1.LastViewedAt, lvAt, "should've gotten LastViewedAt of channel 1")
+
+	lvAt, err = ss.Channel().GetMemberLastViewedAt(context.Background(), c2.Id, userId)
+	require.NoError(t, err, "shouldn't have errored when getting member", err)
+	require.Equal(t, m2.LastViewedAt, lvAt, "should've gotten gotten LastViewedAt of channel 2")
+
+	ss.Channel().InvalidateCacheForChannelMembersNotifyProps(c2.Id)
+}
+
 func testChannelStoreGetMemberForPost(t *testing.T, rctx request.CTX, ss store.Store) {
 	ch := &model.Channel{
 		TeamId:      model.NewId(),
@@ -7477,6 +7542,10 @@ func testChannelStoreRemoveAllDeactivatedMembers(t *testing.T, rctx request.CTX,
 	assert.NoError(t, err)
 	assert.Len(t, d1, 3)
 
+	userIDs, nErr := ss.Channel().GetAllChannelMemberIdsByChannelId(c1.Id)
+	require.NoError(t, nErr)
+	require.ElementsMatch(t, []string{u1.Id, u2.Id, u3.Id}, userIDs)
+
 	// Deactivate users 1 & 2.
 	u1.DeleteAt = model.GetMillis()
 	u2.DeleteAt = model.GetMillis()
@@ -7494,6 +7563,10 @@ func testChannelStoreRemoveAllDeactivatedMembers(t *testing.T, rctx request.CTX,
 	assert.Len(t, d2, 1)
 	assert.Equal(t, u3.Id, d2[0].UserId)
 
+	userIDs, nErr = ss.Channel().GetAllChannelMemberIdsByChannelId(c1.Id)
+	require.NoError(t, nErr)
+	require.ElementsMatch(t, []string{u3.Id}, userIDs)
+
 	// Manually truncate Channels table until testlib can handle cleanups
 	s.GetMasterX().Exec("TRUNCATE Channels")
 }

server/channels/store/storetest/mocks/ChannelStore.go

@@ -432,8 +432,8 @@ func (_m *ChannelStore) GetAll(teamID string) ([]*model.Channel, error) {
 	return r0, r1
 }
 
-// GetAllChannelMembersById provides a mock function with given fields: id
-func (_m *ChannelStore) GetAllChannelMembersById(id string) ([]string, error) {
+// GetAllChannelMemberIdsByChannelId provides a mock function with given fields: id
+func (_m *ChannelStore) GetAllChannelMemberIdsByChannelId(id string) ([]string, error) {
 	ret := _m.Called(id)
 
 	var r0 []string
@@ -1314,6 +1314,30 @@ func (_m *ChannelStore) GetMemberForPost(postID string, userID string, includeAr
 	return r0, r1
 }
 
+// GetMemberLastViewedAt provides a mock function with given fields: ctx, channelID, userID
+func (_m *ChannelStore) GetMemberLastViewedAt(ctx context.Context, channelID string, userID string) (int64, error) {
+	ret := _m.Called(ctx, channelID, userID)
+
+	var r0 int64
+	var r1 error
+	if rf, ok := ret.Get(0).(func(context.Context, string, string) (int64, error)); ok {
+		return rf(ctx, channelID, userID)
+	}
+	if rf, ok := ret.Get(0).(func(context.Context, string, string) int64); ok {
+		r0 = rf(ctx, channelID, userID)
+	} else {
+		r0 = ret.Get(0).(int64)
+	}
+
+	if rf, ok := ret.Get(1).(func(context.Context, string, string) error); ok {
+		r1 = rf(ctx, channelID, userID)
+	} else {
+		r1 = ret.Error(1)
+	}
+
+	return r0, r1
+}
+
 // GetMembers provides a mock function with given fields: channelID, offset, limit
 func (_m *ChannelStore) GetMembers(channelID string, offset int, limit int) (model.ChannelMembers, error) {
 	ret := _m.Called(channelID, offset, limit)