diff --git a/api4/command.go b/api4/command.go
index 350caa5018..7a62028aaf 100644
--- a/api4/command.go
+++ b/api4/command.go
@@ -414,7 +414,6 @@ func listCommandAutocompleteSuggestions(c *Context, w http.ResponseWriter, r *ht
 		ChannelId: query.Get("channel_id"),
 		TeamId:    c.Params.TeamId,
 		RootId:    query.Get("root_id"),
-		ParentId:  query.Get("parent_id"),
 		UserId:    c.AppContext.Session().UserId,
 		T:         c.AppContext.T,
 		Session:   *c.AppContext.Session(),
diff --git a/api4/post_test.go b/api4/post_test.go
index cc40f6a65a..47b7d63c0f 100644
--- a/api4/post_test.go
+++ b/api4/post_test.go
@@ -47,7 +47,6 @@ func TestCreatePost(t *testing.T) {
 	require.Nil(t, rpost.GetProp(model.PropsAddChannelMember), "newly created post shouldn't have Props['add_channel_member'] set")
 
 	post.RootId = rpost.Id
-	post.ParentId = rpost.Id
 	_, _, err2 = client.CreatePost(post)
 	require.NoError(t, err2)
 
@@ -56,12 +55,6 @@ func TestCreatePost(t *testing.T) {
 	require.Error(t, err2)
 	CheckBadRequestStatus(t, resp)
 
-	post.RootId = rpost.Id
-	post.ParentId = "junk"
-	_, resp, err2 = client.CreatePost(post)
-	require.Error(t, err2)
-	CheckBadRequestStatus(t, resp)
-
 	post2 := &model.Post{ChannelId: th.BasicChannel2.Id, Message: "zz" + model.NewId() + "a", CreateAt: 123}
 	rpost2, _, _ := client.CreatePost(post2)
 	require.NotEqual(t, post2.CreateAt, rpost2.CreateAt, "create at should not match")
@@ -130,7 +123,6 @@ func TestCreatePost(t *testing.T) {
 		th.RemovePermissionFromRole(model.PermissionUseChannelMentions.Id, model.ChannelUserRoleId)
 
 		post.RootId = rpost.Id
-		post.ParentId = rpost.Id
 		post.Message = "a post with no channel mentions"
 		_, _, err = client.CreatePost(post)
 		require.NoError(t, err)
@@ -148,19 +140,16 @@ func TestCreatePost(t *testing.T) {
 		}
 
 		post.RootId = rpost.Id
-		post.ParentId = rpost.Id
 		post.Message = "a post with @channel"
 		_, _, err = client.CreatePost(post)
 		require.NoError(t, err)
 
 		post.RootId = rpost.Id
-		post.ParentId = rpost.Id
 		post.Message = "a post with @all"
 		_, _, err = client.CreatePost(post)
 		require.NoError(t, err)
 
 		post.RootId = rpost.Id
-		post.ParentId = rpost.Id
 		post.Message = "a post with @here"
 		_, _, err = client.CreatePost(post)
 		require.NoError(t, err)
@@ -182,7 +171,6 @@ func TestCreatePost(t *testing.T) {
 	})
 
 	post.RootId = ""
-	post.ParentId = ""
 	post.Type = model.PostTypeSystemGeneric
 	_, resp, err := client.CreatePost(post)
 	require.Error(t, err)
@@ -190,13 +178,11 @@ func TestCreatePost(t *testing.T) {
 
 	post.Type = ""
 	post.RootId = rpost2.Id
-	post.ParentId = rpost2.Id
 	_, resp, err = client.CreatePost(post)
 	require.Error(t, err)
 	CheckBadRequestStatus(t, resp)
 
 	post.RootId = ""
-	post.ParentId = ""
 	post.ChannelId = "junk"
 	_, resp, err = client.CreatePost(post)
 	require.Error(t, err)
@@ -1703,7 +1689,7 @@ func TestGetPostsForChannelAroundLastUnread(t *testing.T) {
 	post3 := th.CreatePost()
 	post4 := th.CreatePost()
 	post5 := th.CreatePost()
-	replyPost := &model.Post{ChannelId: channelId, Message: model.NewId(), RootId: post4.Id, ParentId: post4.Id}
+	replyPost := &model.Post{ChannelId: channelId, Message: model.NewId(), RootId: post4.Id}
 	post6, _, err := client.CreatePost(replyPost)
 	require.NoError(t, err)
 	post7, _, err := client.CreatePost(replyPost)
@@ -1907,7 +1893,6 @@ func TestGetPostsForChannelAroundLastUnread(t *testing.T) {
 		ChannelId: channelId,
 		Message:   model.NewId(),
 		RootId:    post4.Id,
-		ParentId:  post4.Id,
 	})
 	require.NoError(t, err)
 	post13 := th.CreatePost()
diff --git a/app/auto_responder_test.go b/app/auto_responder_test.go
index 6fb998200b..51baff292a 100644
--- a/app/auto_responder_test.go
+++ b/app/auto_responder_test.go
@@ -271,7 +271,6 @@ func TestSendAutoResponseSuccess(t *testing.T) {
 		if post.Type == model.PostTypeAutoResponder {
 			autoResponderPostFound = true
 			assert.Equal(t, savedPost.Id, post.RootId)
-			assert.Equal(t, savedPost.Id, post.ParentId)
 		}
 	}
 	assert.True(t, autoResponderPostFound)
@@ -304,7 +303,7 @@ func TestSendAutoResponseSuccessOnThread(t *testing.T) {
 		Message:   "zz" + model.NewId() + "a",
 		UserId:    th.BasicUser.Id,
 		RootId:    parentPost.Id,
-		ParentId:  parentPost.Id},
+	},
 		th.BasicChannel,
 		false, true)
 
@@ -321,7 +320,6 @@ func TestSendAutoResponseSuccessOnThread(t *testing.T) {
 		if post.Type == model.PostTypeAutoResponder {
 			autoResponderPostFound = true
 			assert.Equal(t, savedPost.RootId, post.RootId)
-			assert.Equal(t, savedPost.ParentId, post.ParentId)
 		}
 	}
 	assert.True(t, autoResponderPostFound)
diff --git a/app/command.go b/app/command.go
index 00ef70b414..640103064b 100644
--- a/app/command.go
+++ b/app/command.go
@@ -74,7 +74,6 @@ func (a *App) CreateCommandPost(c *request.Context, post *model.Post, teamID str
 	}
 
 	if (response.ResponseType == "" || response.ResponseType == model.CommandResponseTypeEphemeral) && (response.Text != "" || response.Attachments != nil) {
-		post.ParentId = ""
 		a.SendEphemeralPost(post.UserId, post)
 	}
 
@@ -570,7 +569,6 @@ func (a *App) HandleCommandResponsePost(c *request.Context, command *model.Comma
 	post := &model.Post{}
 	post.ChannelId = args.ChannelId
 	post.RootId = args.RootId
-	post.ParentId = args.ParentId
 	post.UserId = args.UserId
 	post.Type = response.Type
 	post.SetProps(response.Props)
diff --git a/app/command_autocomplete.go b/app/command_autocomplete.go
index c48d11ed68..9957f3c664 100644
--- a/app/command_autocomplete.go
+++ b/app/command_autocomplete.go
@@ -267,7 +267,6 @@ func (a *App) getDynamicListArgument(c *request.Context, commandArgs *model.Comm
 	params.Add("channel_id", commandArgs.ChannelId)
 	params.Add("team_id", commandArgs.TeamId)
 	params.Add("root_id", commandArgs.RootId)
-	params.Add("parent_id", commandArgs.ParentId)
 	params.Add("user_id", commandArgs.UserId)
 	params.Add("site_url", commandArgs.SiteURL)
 
diff --git a/app/import_functions.go b/app/import_functions.go
index 69dca7aa8e..087a848917 100644
--- a/app/import_functions.go
+++ b/app/import_functions.go
@@ -1093,7 +1093,6 @@ func (a *App) importReplies(c *request.Context, data []ReplyImportData, post *mo
 		}
 		reply.UserId = user.Id
 		reply.ChannelId = post.ChannelId
-		reply.ParentId = post.Id
 		reply.RootId = post.Id
 		reply.Message = *replyData.Message
 		reply.CreateAt = *replyData.CreateAt
diff --git a/app/notification.go b/app/notification.go
index 72e7e9cf17..e9f31c3b4c 100644
--- a/app/notification.go
+++ b/app/notification.go
@@ -569,7 +569,6 @@ func (a *App) sendNoUsersNotifiedByGroupInChannel(sender *model.User, post *mode
 	ephemeralPost := &model.Post{
 		UserId:    sender.Id,
 		RootId:    post.RootId,
-		ParentId:  post.ParentId,
 		ChannelId: channel.Id,
 		Message:   T("api.post.check_for_out_of_channel_group_users.message.none", model.StringInterface{"GroupName": group.Name}),
 	}
diff --git a/app/post.go b/app/post.go
index 70c4fb7195..7ae15a63f8 100644
--- a/app/post.go
+++ b/app/post.go
@@ -53,8 +53,7 @@ func (a *App) CreatePostAsUser(c *request.Context, post *model.Post, currentSess
 	rp, err := a.CreatePost(c, post, channel, true, setOnline)
 	if err != nil {
 		if err.Id == "api.post.create_post.root_id.app_error" ||
-			err.Id == "api.post.create_post.channel_root_id.app_error" ||
-			err.Id == "api.post.create_post.parent_id.app_error" {
+			err.Id == "api.post.create_post.channel_root_id.app_error" {
 			err.StatusCode = http.StatusBadRequest
 		}
 
@@ -75,7 +74,6 @@ func (a *App) CreatePostAsUser(c *request.Context, post *model.Post, currentSess
 				post.UserId,
 				&model.Post{
 					ChannelId: channel.Id,
-					ParentId:  post.ParentId,
 					RootId:    post.RootId,
 					UserId:    post.UserId,
 					Message:   T("api.post.create_post.town_square_read_only"),
@@ -230,7 +228,6 @@ func (a *App) CreatePost(c *request.Context, post *model.Post, channel *model.Ch
 			ephemeralPost = &model.Post{
 				UserId:    user.Id,
 				RootId:    post.RootId,
-				ParentId:  post.ParentId,
 				ChannelId: channel.Id,
 				Message:   T("model.post.channel_notifications_disabled_in_channel.message", model.StringInterface{"ChannelName": channel.Name, "Mention": mention}),
 				Props:     model.StringInterface{model.PostPropsMentionHighlightDisabled: true},
@@ -254,17 +251,6 @@ func (a *App) CreatePost(c *request.Context, post *model.Post, channel *model.Ch
 		if rootPost.RootId != "" {
 			return nil, model.NewAppError("createPost", "api.post.create_post.root_id.app_error", nil, "", http.StatusBadRequest)
 		}
-
-		if post.ParentId == "" {
-			post.ParentId = post.RootId
-		}
-
-		if post.RootId != post.ParentId {
-			parent := parentPostList.Posts[post.ParentId]
-			if parent == nil {
-				return nil, model.NewAppError("createPost", "api.post.create_post.parent_id.app_error", nil, "", http.StatusInternalServerError)
-			}
-		}
 	}
 
 	post.Hashtags, _ = model.ParseHashtags(post.Message)
diff --git a/app/post_test.go b/app/post_test.go
index 7cccb59e26..d60bfb89c7 100644
--- a/app/post_test.go
+++ b/app/post_test.go
@@ -346,7 +346,6 @@ func TestPostReplyToPostWhereRootPosterLeftChannel(t *testing.T) {
 		Message:       "asd",
 		ChannelId:     channel.Id,
 		RootId:        rootPost.Id,
-		ParentId:      rootPost.Id,
 		PendingPostId: model.NewId() + ":" + fmt.Sprint(model.GetMillis()),
 		UserId:        userInChannel.Id,
 		CreateAt:      0,
@@ -368,7 +367,6 @@ func TestPostAttachPostToChildPost(t *testing.T) {
 		Message:       "reply one",
 		ChannelId:     channel.Id,
 		RootId:        rootPost.Id,
-		ParentId:      rootPost.Id,
 		PendingPostId: model.NewId() + ":" + fmt.Sprint(model.GetMillis()),
 		UserId:        user.Id,
 		CreateAt:      0,
@@ -381,7 +379,6 @@ func TestPostAttachPostToChildPost(t *testing.T) {
 		Message:       "reply two",
 		ChannelId:     channel.Id,
 		RootId:        res1.Id,
-		ParentId:      res1.Id,
 		PendingPostId: model.NewId() + ":" + fmt.Sprint(model.GetMillis()),
 		UserId:        user.Id,
 		CreateAt:      0,
@@ -394,7 +391,6 @@ func TestPostAttachPostToChildPost(t *testing.T) {
 		Message:       "reply three",
 		ChannelId:     channel.Id,
 		RootId:        rootPost.Id,
-		ParentId:      rootPost.Id,
 		PendingPostId: model.NewId() + ":" + fmt.Sprint(model.GetMillis()),
 		UserId:        user.Id,
 		CreateAt:      0,
@@ -2313,7 +2309,6 @@ func TestReplyToPostWithLag(t *testing.T) {
 			UserId:    th.BasicUser2.Id,
 			ChannelId: th.BasicChannel.Id,
 			RootId:    root.Id,
-			ParentId:  root.Id,
 			Message:   fmt.Sprintf("@%s", th.BasicUser2.Username),
 		}, th.BasicChannel, false, true)
 		require.Nil(t, appErr)
diff --git a/app/slashcommands/auto_posts.go b/app/slashcommands/auto_posts.go
index db19b7ecfd..3c78b09988 100644
--- a/app/slashcommands/auto_posts.go
+++ b/app/slashcommands/auto_posts.go
@@ -70,10 +70,10 @@ func (cfg *AutoPostCreator) UploadTestFile(c *request.Context) ([]string, error)
 }
 
 func (cfg *AutoPostCreator) CreateRandomPost(c *request.Context) (*model.Post, error) {
-	return cfg.CreateRandomPostNested(c, "", "")
+	return cfg.CreateRandomPostNested(c, "")
 }
 
-func (cfg *AutoPostCreator) CreateRandomPostNested(c *request.Context, parentId, rootId string) (*model.Post, error) {
+func (cfg *AutoPostCreator) CreateRandomPostNested(c *request.Context, rootId string) (*model.Post, error) {
 	var fileIDs []string
 	if cfg.HasImage {
 		var err error
@@ -93,7 +93,6 @@ func (cfg *AutoPostCreator) CreateRandomPostNested(c *request.Context, parentId,
 	post := &model.Post{
 		ChannelId: cfg.channelid,
 		UserId:    cfg.userid,
-		ParentId:  parentId,
 		RootId:    rootId,
 		Message:   postText,
 		FileIds:   fileIDs,
diff --git a/app/slashcommands/command_echo.go b/app/slashcommands/command_echo.go
index e92176dff5..3b66a73384 100644
--- a/app/slashcommands/command_echo.go
+++ b/app/slashcommands/command_echo.go
@@ -84,7 +84,6 @@ func (*EchoProvider) DoCommand(a *app.App, c *request.Context, args *model.Comma
 		post := &model.Post{}
 		post.ChannelId = args.ChannelId
 		post.RootId = args.RootId
-		post.ParentId = args.ParentId
 		post.Message = message
 		post.UserId = args.UserId
 
diff --git a/app/slashcommands/command_loadtest.go b/app/slashcommands/command_loadtest.go
index cd410db8b5..b1f16cd58b 100644
--- a/app/slashcommands/command_loadtest.go
+++ b/app/slashcommands/command_loadtest.go
@@ -352,7 +352,7 @@ func (*LoadTestProvider) ThreadedPostCommand(a *app.App, c *request.Context, arg
 		return &model.CommandResponse{Text: "Failed to create a post", ResponseType: model.CommandResponseTypeEphemeral}, err2
 	}
 	for i := 0; i < 1000; i++ {
-		testPoster.CreateRandomPostNested(c, rpost.Id, rpost.Id)
+		testPoster.CreateRandomPostNested(c, rpost.Id)
 	}
 
 	return &model.CommandResponse{Text: "Added threaded post", ResponseType: model.CommandResponseTypeEphemeral}, nil
diff --git a/app/slashcommands/command_test.go b/app/slashcommands/command_test.go
index 8cf528e6f3..33593c290e 100644
--- a/app/slashcommands/command_test.go
+++ b/app/slashcommands/command_test.go
@@ -145,7 +145,6 @@ func TestHandleCommandResponsePost(t *testing.T) {
 		TeamId:    th.BasicTeam.Id,
 		UserId:    th.BasicUser.Id,
 		RootId:    "",
-		ParentId:  "",
 	}
 
 	resp := &model.CommandResponse{
@@ -161,7 +160,6 @@ func TestHandleCommandResponsePost(t *testing.T) {
 	assert.Nil(t, err)
 	assert.Equal(t, args.ChannelId, post.ChannelId)
 	assert.Equal(t, args.RootId, post.RootId)
-	assert.Equal(t, args.ParentId, post.ParentId)
 	assert.Equal(t, args.UserId, post.UserId)
 	assert.Equal(t, resp.Type, post.Type)
 	assert.Equal(t, resp.Props, post.GetProps())
diff --git a/app/webhook.go b/app/webhook.go
index ab5d679327..e45d46a4bb 100644
--- a/app/webhook.go
+++ b/app/webhook.go
@@ -792,7 +792,6 @@ func (a *App) CreateCommandWebhook(commandID string, args *model.CommandArgs) (*
 		UserId:    args.UserId,
 		ChannelId: args.ChannelId,
 		RootId:    args.RootId,
-		ParentId:  args.ParentId,
 	}
 
 	savedHook, err := a.Srv().Store.CommandWebhook().Save(hook)
@@ -844,7 +843,6 @@ func (a *App) HandleCommandWebhook(c *request.Context, hookID string, response *
 		ChannelId: hook.ChannelId,
 		TeamId:    cmd.TeamId,
 		RootId:    hook.RootId,
-		ParentId:  hook.ParentId,
 	}
 
 	if nErr := a.Srv().Store.CommandWebhook().TryUse(hook.Id, 5); nErr != nil {
diff --git a/i18n/en.json b/i18n/en.json
index 99434f5194..6ac210d0f8 100644
--- a/i18n/en.json
+++ b/i18n/en.json
@@ -2148,10 +2148,6 @@
     "id": "api.post.create_post.channel_root_id.app_error",
     "translation": "Invalid ChannelId for RootId parameter."
   },
-  {
-    "id": "api.post.create_post.parent_id.app_error",
-    "translation": "Invalid ParentId parameter."
-  },
   {
     "id": "api.post.create_post.root_id.app_error",
     "translation": "Invalid RootId parameter."
@@ -7822,10 +7818,6 @@
     "id": "model.command_hook.id.app_error",
     "translation": "Invalid command hook id."
   },
-  {
-    "id": "model.command_hook.parent_id.app_error",
-    "translation": "Invalid parent id."
-  },
   {
     "id": "model.command_hook.root_id.app_error",
     "translation": "Invalid root id."
@@ -8618,10 +8610,6 @@
     "id": "model.post.is_valid.original_id.app_error",
     "translation": "Invalid original id."
   },
-  {
-    "id": "model.post.is_valid.parent_id.app_error",
-    "translation": "Invalid parent id."
-  },
   {
     "id": "model.post.is_valid.props.app_error",
     "translation": "Invalid props."
@@ -8630,10 +8618,6 @@
     "id": "model.post.is_valid.root_id.app_error",
     "translation": "Invalid root id."
   },
-  {
-    "id": "model.post.is_valid.root_parent.app_error",
-    "translation": "Invalid root ID must be set if parent ID set."
-  },
   {
     "id": "model.post.is_valid.type.app_error",
     "translation": "Invalid type."
diff --git a/model/command_webhook.go b/model/command_webhook.go
index e6c611d263..8093c1b7ff 100644
--- a/model/command_webhook.go
+++ b/model/command_webhook.go
@@ -14,7 +14,6 @@ type CommandWebhook struct {
 	UserId    string
 	ChannelId string
 	RootId    string
-	ParentId  string
 	UseCount  int
 }
 
@@ -57,9 +56,5 @@ func (o *CommandWebhook) IsValid() *AppError {
 		return NewAppError("CommandWebhook.IsValid", "model.command_hook.root_id.app_error", nil, "", http.StatusBadRequest)
 	}
 
-	if o.ParentId != "" && !IsValidId(o.ParentId) {
-		return NewAppError("CommandWebhook.IsValid", "model.command_hook.parent_id.app_error", nil, "", http.StatusBadRequest)
-	}
-
 	return nil
 }
diff --git a/model/command_webhook_test.go b/model/command_webhook_test.go
index 85788fb5c1..976bccbcce 100644
--- a/model/command_webhook_test.go
+++ b/model/command_webhook_test.go
@@ -43,8 +43,6 @@ func TestCommandWebhookIsValid(t *testing.T) {
 		{func() { h.ChannelId = NewId() }, ""},
 		{func() { h.RootId = "asd" }, "model.command_hook.root_id.app_error"},
 		{func() { h.RootId = NewId() }, ""},
-		{func() { h.ParentId = "asd" }, "model.command_hook.parent_id.app_error"},
-		{func() { h.ParentId = NewId() }, ""},
 	} {
 		tmp := h
 		test.Transform()
diff --git a/model/compliance_post.go b/model/compliance_post.go
index 5e18812b26..5c859ffedf 100644
--- a/model/compliance_post.go
+++ b/model/compliance_post.go
@@ -30,7 +30,6 @@ type CompliancePost struct {
 	PostUpdateAt   int64
 	PostDeleteAt   int64
 	PostRootId     string
-	PostParentId   string
 	PostOriginalId string
 	PostMessage    string
 	PostType       string
@@ -60,7 +59,6 @@ func CompliancePostHeader() []string {
 		"PostUpdateAt",
 		"PostDeleteAt",
 		"PostRootId",
-		"PostParentId",
 		"PostOriginalId",
 		"PostMessage",
 		"PostType",
@@ -113,7 +111,6 @@ func (cp *CompliancePost) Row() []string {
 		postDeleteAt,
 
 		cp.PostRootId,
-		cp.PostParentId,
 		cp.PostOriginalId,
 		cleanComplianceStrings(cp.PostMessage),
 		cp.PostType,
diff --git a/model/post.go b/model/post.go
index 0a4a7470e1..98303a509c 100644
--- a/model/post.go
+++ b/model/post.go
@@ -81,7 +81,6 @@ type Post struct {
 	UserId     string `json:"user_id"`
 	ChannelId  string `json:"channel_id"`
 	RootId     string `json:"root_id"`
-	ParentId   string `json:"parent_id"`
 	OriginalId string `json:"original_id"`
 
 	Message string `json:"message"`
@@ -194,7 +193,6 @@ func (o *Post) ShallowCopy(dst *Post) error {
 	dst.UserId = o.UserId
 	dst.ChannelId = o.ChannelId
 	dst.RootId = o.RootId
-	dst.ParentId = o.ParentId
 	dst.OriginalId = o.OriginalId
 	dst.Message = o.Message
 	dst.MessageSource = o.MessageSource
@@ -302,14 +300,6 @@ func (o *Post) IsValid(maxPostSize int) *AppError {
 		return NewAppError("Post.IsValid", "model.post.is_valid.root_id.app_error", nil, "", http.StatusBadRequest)
 	}
 
-	if !(IsValidId(o.ParentId) || o.ParentId == "") {
-		return NewAppError("Post.IsValid", "model.post.is_valid.parent_id.app_error", nil, "", http.StatusBadRequest)
-	}
-
-	if len(o.ParentId) == 26 && o.RootId == "" {
-		return NewAppError("Post.IsValid", "model.post.is_valid.root_parent.app_error", nil, "", http.StatusBadRequest)
-	}
-
 	if !(len(o.OriginalId) == 26 || o.OriginalId == "") {
 		return NewAppError("Post.IsValid", "model.post.is_valid.original_id.app_error", nil, "", http.StatusBadRequest)
 	}
diff --git a/model/post_test.go b/model/post_test.go
index ace6be13bc..1b1649c0d7 100644
--- a/model/post_test.go
+++ b/model/post_test.go
@@ -56,16 +56,7 @@ func TestPostIsValid(t *testing.T) {
 	require.NotNil(t, err)
 
 	o.RootId = ""
-	o.ParentId = "123"
-	err = o.IsValid(maxPostSize)
-	require.NotNil(t, err)
 
-	o.ParentId = NewId()
-	o.RootId = ""
-	err = o.IsValid(maxPostSize)
-	require.NotNil(t, err)
-
-	o.ParentId = ""
 	o.Message = strings.Repeat("0", maxPostSize+1)
 	err = o.IsValid(maxPostSize)
 	require.NotNil(t, err)
diff --git a/services/cache/lru_test.go b/services/cache/lru_test.go
index eaf52194ef..ed7b3d87c4 100644
--- a/services/cache/lru_test.go
+++ b/services/cache/lru_test.go
@@ -139,7 +139,6 @@ func TestLRUMarshalUnMarshal(t *testing.T) {
 		UserId:        "UserId",
 		ChannelId:     "ChannelId",
 		RootId:        "RootId",
-		ParentId:      "ParentId",
 		OriginalId:    "OriginalId",
 		Message:       "OriginalId",
 		MessageSource: "MessageSource",
@@ -487,7 +486,6 @@ func BenchmarkLRU(b *testing.B) {
 		UserId:        "UserId",
 		ChannelId:     "ChannelId",
 		RootId:        "RootId",
-		ParentId:      "ParentId",
 		OriginalId:    "OriginalId",
 		Message:       "OriginalId",
 		MessageSource: "MessageSource",
diff --git a/services/slackimport/slackimport.go b/services/slackimport/slackimport.go
index a21c1c441c..f9bd9784f9 100644
--- a/services/slackimport/slackimport.go
+++ b/services/slackimport/slackimport.go
@@ -330,7 +330,6 @@ func (si *SlackImporter) slackAddPosts(teamId string, channel *model.Channel, po
 			// If post in thread
 			if sPost.ThreadTS != "" && sPost.ThreadTS != sPost.TimeStamp {
 				newPost.RootId = threads[sPost.ThreadTS]
-				newPost.ParentId = threads[sPost.ThreadTS]
 			}
 			postId := si.oldImportPost(&newPost)
 			// If post is thread starter
@@ -631,8 +630,8 @@ func (si *SlackImporter) oldImportPost(post *model.Post) string {
 	// Workaround for empty messages, which may be the case if they are webhook posts.
 	firstIteration := true
 	firstPostId := ""
-	if post.ParentId != "" {
-		firstPostId = post.ParentId
+	if post.RootId != "" {
+		firstPostId = post.RootId
 	}
 	maxPostSize := si.actions.MaxPostSize()
 	for messageRuneCount := utf8.RuneCountInString(post.Message); messageRuneCount > 0 || firstIteration; messageRuneCount = utf8.RuneCountInString(post.Message) {
@@ -647,7 +646,6 @@ func (si *SlackImporter) oldImportPost(post *model.Post) string {
 		post.Hashtags, _ = model.ParseHashtags(post.Message)
 
 		post.RootId = firstPostId
-		post.ParentId = firstPostId
 
 		_, err := si.store.Post().Save(post)
 		if err != nil {
diff --git a/store/searchtest/helper.go b/store/searchtest/helper.go
index 23be7ae35c..933a9c3a8d 100644
--- a/store/searchtest/helper.go
+++ b/store/searchtest/helper.go
@@ -384,7 +384,6 @@ func (th *SearchTestHelper) createFileInfo(creatorID, postID, name, content, ext
 
 func (th *SearchTestHelper) createReply(userID, message, hashtags string, parent *model.Post, createAt int64, pinned bool) (*model.Post, error) {
 	replyModel := th.createPostModel(userID, parent.ChannelId, message, hashtags, parent.Type, createAt, pinned)
-	replyModel.ParentId = parent.Id
 	replyModel.RootId = parent.Id
 	return th.Store.Post().Save(replyModel)
 }
diff --git a/store/sqlstore/command_webhook_store.go b/store/sqlstore/command_webhook_store.go
index 6e78f54275..48d7316744 100644
--- a/store/sqlstore/command_webhook_store.go
+++ b/store/sqlstore/command_webhook_store.go
@@ -28,7 +28,6 @@ func newSqlCommandWebhookStore(sqlStore *SqlStore) store.CommandWebhookStore {
 		tablec.ColMap("UserId").SetMaxSize(26)
 		tablec.ColMap("ChannelId").SetMaxSize(26)
 		tablec.ColMap("RootId").SetMaxSize(26)
-		tablec.ColMap("ParentId").SetMaxSize(26)
 	}
 
 	return s
diff --git a/store/sqlstore/compliance_store.go b/store/sqlstore/compliance_store.go
index 651d696446..0d101cebb3 100644
--- a/store/sqlstore/compliance_store.go
+++ b/store/sqlstore/compliance_store.go
@@ -137,7 +137,6 @@ func (s SqlComplianceStore) ComplianceExport(job *model.Compliance, cursor model
 			Posts.UpdateAt AS PostUpdateAt,
 			Posts.DeleteAt AS PostDeleteAt,
 			Posts.RootId AS PostRootId,
-			Posts.ParentId AS PostParentId,
 			Posts.OriginalId AS PostOriginalId,
 			Posts.Message AS PostMessage,
 			Posts.Type AS PostType,
@@ -200,7 +199,6 @@ func (s SqlComplianceStore) ComplianceExport(job *model.Compliance, cursor model
 			Posts.UpdateAt AS PostUpdateAt,
 			Posts.DeleteAt AS PostDeleteAt,
 			Posts.RootId AS PostRootId,
-			Posts.ParentId AS PostParentId,
 			Posts.OriginalId AS PostOriginalId,
 			Posts.Message AS PostMessage,
 			Posts.Type AS PostType,
diff --git a/store/sqlstore/integrity.go b/store/sqlstore/integrity.go
index 04bdffebb3..9be36af048 100644
--- a/store/sqlstore/integrity.go
+++ b/store/sqlstore/integrity.go
@@ -150,16 +150,6 @@ func checkPostsFileInfoIntegrity(ss *SqlStore) model.IntegrityCheckResult {
 	})
 }
 
-func checkPostsPostsParentIdIntegrity(ss *SqlStore) model.IntegrityCheckResult {
-	return checkParentChildIntegrity(ss, relationalCheckConfig{
-		parentName:         "Posts",
-		parentIdAttr:       "ParentId",
-		childName:          "Posts",
-		childIdAttr:        "Id",
-		canParentIdBeEmpty: true,
-	})
-}
-
 func checkPostsPostsRootIdIntegrity(ss *SqlStore) model.IntegrityCheckResult {
 	return checkParentChildIntegrity(ss, relationalCheckConfig{
 		parentName:         "Posts",
@@ -474,7 +464,6 @@ func checkCommandsIntegrity(ss *SqlStore, results chan<- model.IntegrityCheckRes
 
 func checkPostsIntegrity(ss *SqlStore, results chan<- model.IntegrityCheckResult) {
 	results <- checkPostsFileInfoIntegrity(ss)
-	results <- checkPostsPostsParentIdIntegrity(ss)
 	results <- checkPostsPostsRootIdIntegrity(ss)
 	results <- checkPostsReactionsIntegrity(ss)
 }
diff --git a/store/sqlstore/integrity_test.go b/store/sqlstore/integrity_test.go
index 717d520a53..51d3f0263f 100644
--- a/store/sqlstore/integrity_test.go
+++ b/store/sqlstore/integrity_test.go
@@ -181,7 +181,6 @@ func createPost(ss store.Store, channelId, userId, rootId, parentId string) *mod
 	m.ChannelId = channelId
 	m.UserId = userId
 	m.RootId = rootId
-	m.ParentId = parentId
 	m.Message = "zz" + model.NewId() + "b"
 	p, _ := ss.Post().Save(&m)
 	return p
@@ -604,51 +603,6 @@ func TestCheckPostsFileInfoIntegrity(t *testing.T) {
 	})
 }
 
-func TestCheckPostsPostsParentIdIntegrity(t *testing.T) {
-	StoreTest(t, func(t *testing.T, ss store.Store) {
-		store := ss.(*SqlStore)
-		dbmap := store.GetMaster()
-
-		t.Run("should generate a report with no records", func(t *testing.T) {
-			result := checkPostsPostsParentIdIntegrity(store)
-			require.NoError(t, result.Err)
-			data := result.Data.(model.RelationalIntegrityCheckData)
-			require.Empty(t, data.Records)
-		})
-
-		t.Run("should generate a report with no records", func(t *testing.T) {
-			root := createPost(ss, model.NewId(), model.NewId(), "", "")
-			parent := createPost(ss, model.NewId(), model.NewId(), root.Id, root.Id)
-			post := createPost(ss, model.NewId(), model.NewId(), root.Id, parent.Id)
-			result := checkPostsPostsParentIdIntegrity(store)
-			require.NoError(t, result.Err)
-			data := result.Data.(model.RelationalIntegrityCheckData)
-			require.Empty(t, data.Records)
-			dbmap.Delete(parent)
-			dbmap.Delete(root)
-			dbmap.Delete(post)
-		})
-
-		t.Run("should generate a report with one record", func(t *testing.T) {
-			root := createPost(ss, model.NewId(), model.NewId(), "", "")
-			parent := createPost(ss, model.NewId(), model.NewId(), root.Id, root.Id)
-			parentId := parent.Id
-			post := createPost(ss, model.NewId(), model.NewId(), root.Id, parent.Id)
-			dbmap.Delete(parent)
-			result := checkPostsPostsParentIdIntegrity(store)
-			require.NoError(t, result.Err)
-			data := result.Data.(model.RelationalIntegrityCheckData)
-			require.Len(t, data.Records, 1)
-			require.Equal(t, model.OrphanedRecord{
-				ParentId: &parentId,
-				ChildId:  &post.Id,
-			}, data.Records[0])
-			dbmap.Delete(root)
-			dbmap.Delete(post)
-		})
-	})
-}
-
 func TestCheckPostsPostsRootIdIntegrity(t *testing.T) {
 	StoreTest(t, func(t *testing.T, ss store.Store) {
 		store := ss.(*SqlStore)
diff --git a/store/sqlstore/post_store.go b/store/sqlstore/post_store.go
index 7758fc5973..2e35d9929d 100644
--- a/store/sqlstore/post_store.go
+++ b/store/sqlstore/post_store.go
@@ -60,7 +60,6 @@ func postSliceColumnsWithTypes() []struct {
 		{"UserId", reflect.String},
 		{"ChannelId", reflect.String},
 		{"RootId", reflect.String},
-		{"ParentId", reflect.String},
 		{"OriginalId", reflect.String},
 		{"Message", reflect.String},
 		{"Type", reflect.String},
@@ -84,7 +83,6 @@ func postToSlice(post *model.Post) []interface{} {
 		post.UserId,
 		post.ChannelId,
 		post.RootId,
-		post.ParentId,
 		post.OriginalId,
 		post.Message,
 		post.Type,
@@ -141,7 +139,6 @@ func newSqlPostStore(sqlStore *SqlStore, metrics einterfaces.MetricsInterface) s
 		table.ColMap("UserId").SetMaxSize(26)
 		table.ColMap("ChannelId").SetMaxSize(26)
 		table.ColMap("RootId").SetMaxSize(26)
-		table.ColMap("ParentId").SetMaxSize(26)
 		table.ColMap("OriginalId").SetMaxSize(26)
 		table.ColMap("Message").SetMaxSize(model.PostMessageMaxBytesV2)
 		table.ColMap("Type").SetMaxSize(26)
@@ -2229,7 +2226,7 @@ func (s *SqlPostStore) GetDirectPostParentsForExportAfter(limit int, afterId str
 		Join("Users ON p.UserId = Users.Id").
 		Where(sq.And{
 			sq.Gt{"p.Id": afterId},
-			sq.Eq{"p.ParentId": string("")},
+			sq.Eq{"p.RootId": string("")},
 			sq.Eq{"p.DeleteAt": int(0)},
 			sq.Eq{"Channels.DeleteAt": int(0)},
 			sq.Eq{"Users.DeleteAt": int(0)},
diff --git a/store/sqlstore/upgrade.go b/store/sqlstore/upgrade.go
index ce87aa0210..9343db541b 100644
--- a/store/sqlstore/upgrade.go
+++ b/store/sqlstore/upgrade.go
@@ -1311,6 +1311,11 @@ func upgradeDatabaseToVersion600(sqlStore *SqlStore) {
 	sqlStore.AlterColumnTypeIfExists("Users", "NotifyProps", "JSON", "jsonb")
 	sqlStore.AlterColumnTypeIfExists("Users", "Timezone", "JSON", "jsonb")
 
+	sqlStore.GetMaster().ExecNoTimeout("UPDATE Posts SET RootId = ParentId WHERE RootId = '' AND RootId != ParentId")
+	sqlStore.RemoveColumnIfExists("Posts", "ParentId")
+	sqlStore.GetMaster().ExecNoTimeout("UPDATE CommandWebhooks SET RootId = ParentId WHERE RootId = '' AND RootId != ParentId")
+	sqlStore.RemoveColumnIfExists("CommandWebhooks", "ParentId")
+
 	// saveSchemaVersion(sqlStore, Version600)
 	// }
 }
diff --git a/store/sqlstore/upgrade_test.go b/store/sqlstore/upgrade_test.go
index c1a39e6d06..1e2dcfbd61 100644
--- a/store/sqlstore/upgrade_test.go
+++ b/store/sqlstore/upgrade_test.go
@@ -125,13 +125,12 @@ func createChannelMemberWithLastViewAt(ss store.Store, channelId, userId string,
 	cm, _ := ss.Channel().SaveMember(&m)
 	return cm
 }
-func createPostWithTimestamp(ss store.Store, channelId, userId, rootId, parentId string, timestamp int64) *model.Post {
+func createPostWithTimestamp(ss store.Store, channelId, userId, rootId string, timestamp int64) *model.Post {
 	m := model.Post{}
 	m.CreateAt = timestamp
 	m.ChannelId = channelId
 	m.UserId = userId
 	m.RootId = rootId
-	m.ParentId = parentId
 	m.Message = "zz" + model.NewId() + "b"
 	p, _ := ss.Post().Save(&m)
 	return p
@@ -225,10 +224,10 @@ func TestMsgCountRootMigration(t *testing.T) {
 						}
 						for i, pt := range testChannel.PostTimes {
 							rt := testChannel.ReplyTimes[i]
-							post := createPostWithTimestamp(ss, channel.Id, model.NewId(), "", "", pt)
+							post := createPostWithTimestamp(ss, channel.Id, model.NewId(), "", pt)
 							require.NotNil(t, post)
 							if rt > 0 {
-								reply := createPostWithTimestamp(ss, channel.Id, model.NewId(), post.Id, post.Id, rt)
+								reply := createPostWithTimestamp(ss, channel.Id, model.NewId(), post.Id, rt)
 								require.NotNil(t, reply)
 							}
 						}
@@ -276,12 +275,12 @@ func TestFixCRTCountsAndUnreads(t *testing.T) {
 		//   - user2: reply 2 to root post 1
 		//   - user1: reply 3 to root post 1
 		//   - user2: reply 4 to root post 1
-		rootPost1 := createPostWithTimestamp(ss, c1.Id, uId2, "", "", 1)
+		rootPost1 := createPostWithTimestamp(ss, c1.Id, uId2, "", 1)
 		lastReplyAt := int64(40)
-		_ = createPostWithTimestamp(ss, c1.Id, uId1, rootPost1.Id, rootPost1.Id, 10)
-		_ = createPostWithTimestamp(ss, c1.Id, uId2, rootPost1.Id, rootPost1.Id, 20)
-		_ = createPostWithTimestamp(ss, c1.Id, uId1, rootPost1.Id, rootPost1.Id, 30)
-		_ = createPostWithTimestamp(ss, c1.Id, uId2, rootPost1.Id, rootPost1.Id, lastReplyAt)
+		_ = createPostWithTimestamp(ss, c1.Id, uId1, rootPost1.Id, 10)
+		_ = createPostWithTimestamp(ss, c1.Id, uId2, rootPost1.Id, 20)
+		_ = createPostWithTimestamp(ss, c1.Id, uId1, rootPost1.Id, 30)
+		_ = createPostWithTimestamp(ss, c1.Id, uId2, rootPost1.Id, lastReplyAt)
 
 		// Check created thread is good
 		goodThread1, err := ss.Thread().Get(rootPost1.Id)
diff --git a/store/storetest/channel_store.go b/store/storetest/channel_store.go
index 0c7396ea1a..d916de976b 100644
--- a/store/storetest/channel_store.go
+++ b/store/storetest/channel_store.go
@@ -5952,7 +5952,6 @@ func testChannelStoreGetPinnedPosts(t *testing.T, ss store.Store) {
 		post3, err := ss.Post().Save(&model.Post{
 			ChannelId: channelId,
 			UserId:    userId,
-			ParentId:  post1.Id,
 			RootId:    post1.Id,
 			Message:   "message",
 			IsPinned:  true,
diff --git a/store/storetest/file_info_store.go b/store/storetest/file_info_store.go
index 4e8801ef9a..2884dedc5d 100644
--- a/store/storetest/file_info_store.go
+++ b/store/storetest/file_info_store.go
@@ -658,7 +658,6 @@ func testFileInfoStoreGetFilesBatchForIndexing(t *testing.T, ss store.Store) {
 	o3 := &model.Post{}
 	o3.ChannelId = c1.Id
 	o3.UserId = model.NewId()
-	o3.ParentId = o1.Id
 	o3.RootId = o1.Id
 	o3.Message = "zz" + model.NewId() + "QQQQQQQQQQ"
 	o3, err = ss.Post().Save(o3)
diff --git a/store/storetest/post_store.go b/store/storetest/post_store.go
index b5697b7611..30bf7470b6 100644
--- a/store/storetest/post_store.go
+++ b/store/storetest/post_store.go
@@ -525,7 +525,6 @@ func testPostStoreUpdate(t *testing.T, ss store.Store) {
 	o2.ChannelId = o1.ChannelId
 	o2.UserId = model.NewId()
 	o2.Message = "zz" + model.NewId() + "CCCCCCCCC"
-	o2.ParentId = o1.Id
 	o2.RootId = o1.Id
 	o2, err = ss.Post().Save(o2)
 	require.NoError(t, err)
@@ -657,7 +656,6 @@ func testPostStoreDelete1Level(t *testing.T, ss store.Store) {
 	o2.ChannelId = o1.ChannelId
 	o2.UserId = model.NewId()
 	o2.Message = "zz" + model.NewId() + "b"
-	o2.ParentId = o1.Id
 	o2.RootId = o1.Id
 	o2, err = ss.Post().Save(o2)
 	require.NoError(t, err)
@@ -684,7 +682,6 @@ func testPostStoreDelete2Level(t *testing.T, ss store.Store) {
 	o2.ChannelId = o1.ChannelId
 	o2.UserId = model.NewId()
 	o2.Message = "zz" + model.NewId() + "b"
-	o2.ParentId = o1.Id
 	o2.RootId = o1.Id
 	o2, err = ss.Post().Save(o2)
 	require.NoError(t, err)
@@ -693,7 +690,6 @@ func testPostStoreDelete2Level(t *testing.T, ss store.Store) {
 	o3.ChannelId = o1.ChannelId
 	o3.UserId = model.NewId()
 	o3.Message = "zz" + model.NewId() + "b"
-	o3.ParentId = o2.Id
 	o3.RootId = o1.Id
 	o3, err = ss.Post().Save(o3)
 	require.NoError(t, err)
@@ -733,7 +729,6 @@ func testPostStorePermDelete1Level(t *testing.T, ss store.Store) {
 	o2.ChannelId = o1.ChannelId
 	o2.UserId = model.NewId()
 	o2.Message = "zz" + model.NewId() + "b"
-	o2.ParentId = o1.Id
 	o2.RootId = o1.Id
 	o2, err = ss.Post().Save(o2)
 	require.NoError(t, err)
@@ -773,7 +768,6 @@ func testPostStorePermDelete1Level2(t *testing.T, ss store.Store) {
 	o2.ChannelId = o1.ChannelId
 	o2.UserId = model.NewId()
 	o2.Message = "zz" + model.NewId() + "b"
-	o2.ParentId = o1.Id
 	o2.RootId = o1.Id
 	o2, err = ss.Post().Save(o2)
 	require.NoError(t, err)
@@ -810,7 +804,6 @@ func testPostStoreGetWithChildren(t *testing.T, ss store.Store) {
 	o2.ChannelId = o1.ChannelId
 	o2.UserId = model.NewId()
 	o2.Message = "zz" + model.NewId() + "b"
-	o2.ParentId = o1.Id
 	o2.RootId = o1.Id
 	o2, err = ss.Post().Save(o2)
 	require.NoError(t, err)
@@ -819,7 +812,6 @@ func testPostStoreGetWithChildren(t *testing.T, ss store.Store) {
 	o3.ChannelId = o1.ChannelId
 	o3.UserId = model.NewId()
 	o3.Message = "zz" + model.NewId() + "b"
-	o3.ParentId = o2.Id
 	o3.RootId = o1.Id
 	o3, err = ss.Post().Save(o3)
 	require.NoError(t, err)
@@ -859,7 +851,6 @@ func testPostStoreGetPostsWithDetails(t *testing.T, ss store.Store) {
 	o2.ChannelId = o1.ChannelId
 	o2.UserId = model.NewId()
 	o2.Message = "zz" + model.NewId() + "b"
-	o2.ParentId = o1.Id
 	o2.RootId = o1.Id
 	_, err = ss.Post().Save(o2)
 	require.NoError(t, err)
@@ -869,7 +860,6 @@ func testPostStoreGetPostsWithDetails(t *testing.T, ss store.Store) {
 	o2a.ChannelId = o1.ChannelId
 	o2a.UserId = model.NewId()
 	o2a.Message = "zz" + model.NewId() + "b"
-	o2a.ParentId = o1.Id
 	o2a.RootId = o1.Id
 	o2a, err = ss.Post().Save(o2a)
 	require.NoError(t, err)
@@ -879,7 +869,6 @@ func testPostStoreGetPostsWithDetails(t *testing.T, ss store.Store) {
 	o3.ChannelId = o1.ChannelId
 	o3.UserId = model.NewId()
 	o3.Message = "zz" + model.NewId() + "b"
-	o3.ParentId = o1.Id
 	o3.RootId = o1.Id
 	o3, err = ss.Post().Save(o3)
 	require.NoError(t, err)
@@ -897,7 +886,6 @@ func testPostStoreGetPostsWithDetails(t *testing.T, ss store.Store) {
 	o5.ChannelId = o1.ChannelId
 	o5.UserId = model.NewId()
 	o5.Message = "zz" + model.NewId() + "b"
-	o5.ParentId = o4.Id
 	o5.RootId = o4.Id
 	o5, err = ss.Post().Save(o5)
 	require.NoError(t, err)
@@ -1073,7 +1061,6 @@ func testPostStoreGetPostsBeforeAfter(t *testing.T, ss store.Store) {
 		post3, err := ss.Post().Save(&model.Post{
 			ChannelId: channelId,
 			UserId:    userId,
-			ParentId:  post1.Id,
 			RootId:    post1.Id,
 			Message:   "message",
 		})
@@ -1085,7 +1072,6 @@ func testPostStoreGetPostsBeforeAfter(t *testing.T, ss store.Store) {
 			ChannelId: channelId,
 			UserId:    userId,
 			RootId:    post2.Id,
-			ParentId:  post2.Id,
 			Message:   "message",
 		})
 		require.NoError(t, err)
@@ -1103,7 +1089,6 @@ func testPostStoreGetPostsBeforeAfter(t *testing.T, ss store.Store) {
 		post6, err := ss.Post().Save(&model.Post{
 			ChannelId: channelId,
 			UserId:    userId,
-			ParentId:  post2.Id,
 			RootId:    post2.Id,
 			Message:   "message",
 		})
@@ -1174,7 +1159,6 @@ func testPostStoreGetPostsBeforeAfter(t *testing.T, ss store.Store) {
 		post3, err := ss.Post().Save(&model.Post{
 			ChannelId: channelId,
 			UserId:    userId,
-			ParentId:  post1.Id,
 			RootId:    post1.Id,
 			Message:   "post3",
 		})
@@ -1186,7 +1170,6 @@ func testPostStoreGetPostsBeforeAfter(t *testing.T, ss store.Store) {
 			ChannelId: channelId,
 			UserId:    userId,
 			RootId:    post2.Id,
-			ParentId:  post2.Id,
 			Message:   "post4",
 		})
 		require.NoError(t, err)
@@ -1204,7 +1187,6 @@ func testPostStoreGetPostsBeforeAfter(t *testing.T, ss store.Store) {
 		post6, err := ss.Post().Save(&model.Post{
 			ChannelId: channelId,
 			UserId:    userId,
-			ParentId:  post2.Id,
 			RootId:    post2.Id,
 			Message:   "post6",
 		})
@@ -1283,7 +1265,6 @@ func testPostStoreGetPostsBeforeAfter(t *testing.T, ss store.Store) {
 		post3, err := ss.Post().Save(&model.Post{
 			ChannelId: channelId,
 			UserId:    userId,
-			ParentId:  post1.Id,
 			RootId:    post1.Id,
 			Message:   "post3",
 		})
@@ -1295,7 +1276,6 @@ func testPostStoreGetPostsBeforeAfter(t *testing.T, ss store.Store) {
 			ChannelId: channelId,
 			UserId:    userId,
 			RootId:    post2.Id,
-			ParentId:  post2.Id,
 			Message:   "post4",
 		})
 		require.NoError(t, err)
@@ -1313,7 +1293,6 @@ func testPostStoreGetPostsBeforeAfter(t *testing.T, ss store.Store) {
 		post6, err := ss.Post().Save(&model.Post{
 			ChannelId: channelId,
 			UserId:    userId,
-			ParentId:  post2.Id,
 			RootId:    post2.Id,
 			Message:   "post6",
 		})
@@ -1606,7 +1585,6 @@ func testPostStoreGetPostBeforeAfter(t *testing.T, ss store.Store) {
 	o0a.ChannelId = channelId
 	o0a.UserId = model.NewId()
 	o0a.Message = "zz" + model.NewId() + "b"
-	o0a.ParentId = o1.Id
 	o0a.RootId = o1.Id
 	_, err = ss.Post().Save(o0a)
 	require.NoError(t, err)
@@ -1616,7 +1594,6 @@ func testPostStoreGetPostBeforeAfter(t *testing.T, ss store.Store) {
 	o0b.ChannelId = channelId
 	o0b.UserId = model.NewId()
 	o0b.Message = "deleted message"
-	o0b.ParentId = o1.Id
 	o0b.RootId = o1.Id
 	o0b.DeleteAt = 1
 	_, err = ss.Post().Save(o0b)
@@ -1643,7 +1620,6 @@ func testPostStoreGetPostBeforeAfter(t *testing.T, ss store.Store) {
 	o2a.ChannelId = channelId
 	o2a.UserId = model.NewId()
 	o2a.Message = "zz" + model.NewId() + "b"
-	o2a.ParentId = o2.Id
 	o2a.RootId = o2.Id
 	_, err = ss.Post().Save(o2a)
 	require.NoError(t, err)
@@ -2252,7 +2228,6 @@ func testPostStoreGetPostsCreatedAt(t *testing.T, ss store.Store) {
 	o2.ChannelId = o1.ChannelId
 	o2.UserId = model.NewId()
 	o2.Message = "zz" + model.NewId() + "b"
-	o2.ParentId = o1.Id
 	o2.RootId = o1.Id
 	o2.CreateAt = createTime + 1
 	_, err = ss.Post().Save(o2)
@@ -2282,7 +2257,6 @@ func testPostStoreOverwriteMultiple(t *testing.T, ss store.Store) {
 	o2.ChannelId = o1.ChannelId
 	o2.UserId = model.NewId()
 	o2.Message = "zz" + model.NewId() + "CCCCCCCCC"
-	o2.ParentId = o1.Id
 	o2.RootId = o1.Id
 	o2, err = ss.Post().Save(o2)
 	require.NoError(t, err)
@@ -2409,7 +2383,6 @@ func testPostStoreOverwrite(t *testing.T, ss store.Store) {
 	o2.ChannelId = o1.ChannelId
 	o2.UserId = model.NewId()
 	o2.Message = "zz" + model.NewId() + "CCCCCCCCC"
-	o2.ParentId = o1.Id
 	o2.RootId = o1.Id
 	o2, err = ss.Post().Save(o2)
 	require.NoError(t, err)
@@ -2583,7 +2556,6 @@ func testPostStoreGetPostsBatchForIndexing(t *testing.T, ss store.Store) {
 	o3 := &model.Post{}
 	o3.ChannelId = c1.Id
 	o3.UserId = model.NewId()
-	o3.ParentId = o1.Id
 	o3.RootId = o1.Id
 	o3.Message = "zz" + model.NewId() + "QQQQQQQQQQ"
 	o3, err = ss.Post().Save(o3)
@@ -2935,7 +2907,6 @@ func testPostStoreGetRepliesForExport(t *testing.T, ss store.Store) {
 	p2.UserId = u1.Id
 	p2.Message = "zz" + model.NewId() + "AAAAAAAAAAA"
 	p2.CreateAt = 1001
-	p2.ParentId = p1.Id
 	p2.RootId = p1.Id
 	p2, nErr = ss.Post().Save(p2)
 	require.NoError(t, nErr)
diff --git a/store/storetest/thread_store.go b/store/storetest/thread_store.go
index 983e2f8398..dec40db8e2 100644
--- a/store/storetest/thread_store.go
+++ b/store/storetest/thread_store.go
@@ -455,7 +455,6 @@ func threadStoreCreateReply(t *testing.T, ss store.Store, channelID, postID stri
 		UserId:    model.NewId(),
 		CreateAt:  createAt,
 		RootId:    postID,
-		ParentId:  postID,
 	})
 	require.NoError(t, err)
 	return reply