diff --git a/internal/core/cache.go b/internal/core/cache.go
index 25394957..08eae18f 100644
--- a/internal/core/cache.go
+++ b/internal/core/cache.go
@@ -1,9 +1,5 @@
 package core
 
-import (
-	"github.com/rocboss/paopao-ce/internal/model"
-)
-
 const (
 	IdxActNop IndexActionT = iota + 1
 	IdxActCreatePost
@@ -33,6 +29,6 @@ func (a IndexActionT) String() string {
 
 // CacheIndexService cache index service interface
 type CacheIndexService interface {
-	IndexPosts(offset int, limit int) ([]*model.PostFormated, bool)
+	IndexPostsService
 	SendAction(active IndexActionT)
 }
diff --git a/internal/core/core.go b/internal/core/core.go
index cdd1a92b..f815525b 100644
--- a/internal/core/core.go
+++ b/internal/core/core.go
@@ -8,6 +8,7 @@ import (
 type DataService interface {
 	WalletService
 	SearchService
+	IndexPostsService
 
 	GetComments(conditions *model.ConditionsT, offset, limit int) ([]*model.Comment, error)
 	GetCommentByID(id int64) (*model.Comment, error)
@@ -34,7 +35,6 @@ type DataService interface {
 	LockPost(post *model.Post) error
 	StickPost(post *model.Post) error
 	GetPostByID(id int64) (*model.Post, error)
-	IndexPosts(offset int, limit int) ([]*model.PostFormated, error)
 	GetPosts(conditions *model.ConditionsT, offset, limit int) ([]*model.Post, error)
 	GetPostCount(conditions *model.ConditionsT) (int64, error)
 	UpdatePost(post *model.Post) error
diff --git a/internal/core/index.go b/internal/core/index.go
new file mode 100644
index 00000000..afc02048
--- /dev/null
+++ b/internal/core/index.go
@@ -0,0 +1,9 @@
+package core
+
+import (
+	"github.com/rocboss/paopao-ce/internal/model"
+)
+
+type IndexPostsService interface {
+	IndexPosts(offset int, limit int) ([]*model.PostFormated, error)
+}
diff --git a/internal/dao/cache_index.go b/internal/dao/cache_index.go
index ce213789..b8626be9 100644
--- a/internal/dao/cache_index.go
+++ b/internal/dao/cache_index.go
@@ -1,6 +1,7 @@
 package dao
 
 import (
+	"errors"
 	"time"
 
 	"github.com/rocboss/paopao-ce/internal/conf"
@@ -9,6 +10,10 @@ import (
 	"github.com/sirupsen/logrus"
 )
 
+var (
+	errNotExist = errors.New("index posts cache not exist")
+)
+
 func newSimpleCacheIndexServant(getIndexPosts func(offset, limit int) ([]*model.PostFormated, error)) *simpleCacheIndexServant {
 	s := conf.SimpleCacheIndexSetting
 	cacheIndex := &simpleCacheIndexServant{
@@ -43,15 +48,15 @@ func newSimpleCacheIndexServant(getIndexPosts func(offset, limit int) ([]*model.
 	return cacheIndex
 }
 
-func (s *simpleCacheIndexServant) IndexPosts(offset int, limit int) ([]*model.PostFormated, bool) {
+func (s *simpleCacheIndexServant) IndexPosts(offset int, limit int) ([]*model.PostFormated, error) {
 	posts := s.atomicIndex.Load().([]*model.PostFormated)
 	end := offset + limit
 	size := len(posts)
 	logrus.Debugf("get index posts from posts: %d offset:%d limit:%d start:%d, end:%d", size, offset, limit, offset, end)
 	if size >= end {
-		return posts[offset:end], true
+		return posts[offset:end], nil
 	}
-	return nil, false
+	return nil, errNotExist
 }
 
 func (s *simpleCacheIndexServant) SendAction(act core.IndexActionT) {
diff --git a/internal/dao/post_index.go b/internal/dao/post_index.go
index 53a0913d..0a184dd7 100644
--- a/internal/dao/post_index.go
+++ b/internal/dao/post_index.go
@@ -8,7 +8,7 @@ import (
 
 func (d *dataServant) IndexPosts(offset int, limit int) ([]*model.PostFormated, error) {
 	if d.useCacheIndex {
-		if posts, ok := d.cacheIndex.IndexPosts(offset, limit); ok {
+		if posts, err := d.cacheIndex.IndexPosts(offset, limit); err == nil {
 			logrus.Debugln("get index posts from cached")
 			return posts, nil
 		}