diff --git a/cmd/cql-observer/api.go b/cmd/cql-observer/api.go
index 8e4c0c483..6738d97b6 100644
--- a/cmd/cql-observer/api.go
+++ b/cmd/cql-observer/api.go
@@ -57,6 +57,32 @@ type explorerAPI struct {
 	service *Service
 }
 
+type paginationOps struct {
+	page      int
+	size      int
+	queryType types.QueryType
+}
+
+func newPaginationFromReq(r *http.Request) (op *paginationOps) {
+	op = &paginationOps{}
+	op.page, _ = strconv.Atoi(r.URL.Query().Get("page"))
+	op.size, _ = strconv.Atoi(r.URL.Query().Get("size"))
+	if r.URL.Query().Get("type") == types.ReadQuery.String() {
+		op.queryType = types.ReadQuery
+	} else if r.URL.Query().Get("type") == types.WriteQuery.String() {
+		op.queryType = types.WriteQuery
+	} else {
+		op.queryType = types.NumberOfQueryType
+	}
+	if op.page <= 0 {
+		op.page = 1
+	}
+	if op.size <= 0 {
+		op.size = 10
+	}
+	return
+}
+
 func (a *explorerAPI) GetAck(rw http.ResponseWriter, r *http.Request) {
 	vars := mux.Vars(r)
 
@@ -175,7 +201,9 @@ func (a *explorerAPI) GetBlockV3(rw http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	sendResponse(200, true, "", a.formatBlockV3(count, height, block), rw)
+	op := newPaginationFromReq(r)
+
+	sendResponse(200, true, "", a.formatBlockV3(count, height, block, op), rw)
 }
 
 func (a *explorerAPI) GetBlockByCount(rw http.ResponseWriter, r *http.Request) {
@@ -239,7 +267,9 @@ func (a *explorerAPI) GetBlockByCountV3(rw http.ResponseWriter, r *http.Request)
 		return
 	}
 
-	sendResponse(200, true, "", a.formatBlockV3(count, height, block), rw)
+	op := newPaginationFromReq(r)
+
+	sendResponse(200, true, "", a.formatBlockV3(count, height, block, op), rw)
 }
 
 func (a *explorerAPI) GetBlockByHeight(rw http.ResponseWriter, r *http.Request) {
@@ -303,7 +333,9 @@ func (a *explorerAPI) GetBlockByHeightV3(rw http.ResponseWriter, r *http.Request
 		return
 	}
 
-	sendResponse(200, true, "", a.formatBlockV3(count, height, block), rw)
+	op := newPaginationFromReq(r)
+
+	sendResponse(200, true, "", a.formatBlockV3(count, height, block, op), rw)
 }
 
 func (a *explorerAPI) GetHighestBlock(rw http.ResponseWriter, r *http.Request) {
@@ -396,7 +428,9 @@ func (a *explorerAPI) GetHighestBlockV3(rw http.ResponseWriter, r *http.Request)
 		return
 	}
 
-	sendResponse(200, true, "", a.formatBlockV3(count, height, block), rw)
+	op := newPaginationFromReq(r)
+
+	sendResponse(200, true, "", a.formatBlockV3(count, height, block, op), rw)
 }
 
 func (a *explorerAPI) formatBlock(height int32, b *types.Block) (res map[string]interface{}) {
@@ -425,30 +459,96 @@ func (a *explorerAPI) formatBlockV2(count, height int32, b *types.Block) (res ma
 	return
 }
 
-func (a *explorerAPI) formatBlockV3(count, height int32, b *types.Block) (res map[string]interface{}) {
+func (a *explorerAPI) formatBlockV3(count, height int32, b *types.Block,
+	pagination *paginationOps) (res map[string]interface{}) {
 	res = a.formatBlockV2(count, height, b)
 	blockRes := res["block"].(map[string]interface{})
-	blockRes["acks"] = func() (acks []interface{}) {
-		acks = make([]interface{}, 0, len(b.Acks))
-
-		for _, ack := range b.Acks {
-			acks = append(acks, a.formatAck(ack)["ack"])
-		}
-
-		return
-	}()
 	blockRes["queries"] = func() (tracks []interface{}) {
-		tracks = make([]interface{}, 0, len(b.QueryTxs))
+		tracks = make([]interface{}, 0, len(b.QueryTxs)+len(b.FailedReqs))
+
+		var (
+			offset = (pagination.page - 1) * pagination.size
+			end    = pagination.page * pagination.size
+			pos    = 0
+		)
 
 		for _, tx := range b.QueryTxs {
+			if (pagination.queryType == types.ReadQuery || pagination.queryType == types.WriteQuery) &&
+				tx.Request.Header.QueryType != pagination.queryType {
+				// count all
+				continue
+			}
+
+			if pos >= end {
+				return
+			}
+
 			t := a.formatRequest(tx.Request)
 			t["response"] = a.formatResponseHeader(tx.Response)["response"]
-			tracks = append(tracks, t)
+			t["failed"] = false
+
+			if pos >= offset {
+				tracks = append(tracks, t)
+			}
+
+			pos++
+		}
+
+		for _, req := range b.FailedReqs {
+			if (pagination.queryType == types.ReadQuery || pagination.queryType == types.WriteQuery) &&
+				req.Header.QueryType != pagination.queryType {
+				// count all
+				continue
+			}
+
+			if pos >= end {
+				return
+			}
+
+			t := a.formatRequest(req)
+			t["failed"] = true
+
+			if pos >= offset {
+				tracks = append(tracks, t)
+			}
+
+			pos++
 		}
 
 		return
 	}()
 
+	if pagination != nil {
+		blockRes["pagination"] = func() (res map[string]interface{}) {
+			// pagination features
+			res = map[string]interface{}{}
+			res["page"] = pagination.page
+			res["size"] = pagination.size
+
+			if pagination.queryType != types.ReadQuery && pagination.queryType != types.WriteQuery {
+				res["total"] = len(b.QueryTxs) + len(b.FailedReqs)
+			} else {
+				var total int
+
+				for _, tx := range b.QueryTxs {
+					if tx.Request.Header.QueryType == pagination.queryType {
+						total++
+					}
+				}
+
+				for _, req := range b.FailedReqs {
+					if req.Header.QueryType == pagination.queryType {
+						total++
+					}
+				}
+
+				res["total"] = total
+			}
+
+			return
+		}()
+	}
+
 	return
 }
 
diff --git a/cmd/cql-observer/observation_test.go b/cmd/cql-observer/observation_test.go
index 99d739d4f..54c6e1e2d 100644
--- a/cmd/cql-observer/observation_test.go
+++ b/cmd/cql-observer/observation_test.go
@@ -422,20 +422,55 @@ func TestFullProcess(t *testing.T) {
 		genesisHash := ensureSuccess(res.String("block", "hash")).(string)
 
 		// test get first containable block
-		res, err = getJSON("v3/height/%v/1", dbID)
-		So(err, ShouldBeNil)
-		So(ensureSuccess(res.Interface("block")), ShouldNotBeNil)
-		So(ensureSuccess(res.Int("block", "height")), ShouldEqual, 1)
-		So(ensureSuccess(res.String("block", "hash")), ShouldNotBeEmpty)
-		So(ensureSuccess(res.String("block", "genesis_hash")), ShouldEqual, genesisHash)
-		So(ensureSuccess(res.ArrayOfObjects("block", "queries")), ShouldNotBeEmpty)
-		blockHash := ensureSuccess(res.String("block", "hash")).(string)
-		byHeightBlockResult := ensureSuccess(res.Interface())
+		var (
+			blockHash           string
+			byHeightBlockResult interface{}
+		)
+
+		// access 5 blocks
+		for i := 1; i <= 5; i++ {
+			res, err = getJSON("v3/height/%v/%d", dbID, i)
+			So(err, ShouldBeNil)
+			So(ensureSuccess(res.Interface("block")), ShouldNotBeNil)
+			So(ensureSuccess(res.Int("block", "height")), ShouldEqual, i)
+			So(ensureSuccess(res.String("block", "hash")), ShouldNotBeEmpty)
+			So(ensureSuccess(res.String("block", "genesis_hash")), ShouldEqual, genesisHash)
+			if len(ensureSuccess(res.ArrayOfObjects("block", "queries")).([]map[string]interface{})) == 0 {
+				// got empty block
+				log.WithField("block", res).Debugf("got empty block, try next index")
+				continue
+			}
+			So(ensureSuccess(res.ArrayOfObjects("block", "queries")), ShouldNotBeEmpty)
+			blockHash = ensureSuccess(res.String("block", "hash")).(string)
+			byHeightBlockResult = ensureSuccess(res.Interface())
+			break
+		}
 
 		// test get block by hash
-		res, err = getJSON("v3/block/%v/%v", dbID, blockHash)
+		res, err = getJSON("v3/block/%v/%v?size=1000", dbID, blockHash)
+		So(err, ShouldBeNil)
+		So(ensureSuccess(res.ArrayOfObjects("block", "queries")), ShouldResemble,
+			ensureSuccess(jsonq.NewQuery(byHeightBlockResult).ArrayOfObjects("block", "queries")))
+
+		// test get block by hash v3 with pagination
+		res, err = getJSON("v3/block/%v/%v?page=10000&size=10", dbID, blockHash)
+		So(err, ShouldBeNil)
+		So(ensureSuccess(res.ArrayOfObjects("block", "queries")), ShouldBeEmpty)
+
+		// test get block with page size = 1
+		res, err = getJSON("v3/block/%v/%v?page=1&size=1", dbID, blockHash)
+		So(err, ShouldBeNil)
+		So(ensureSuccess(res.ArrayOfObjects("block", "queries")), ShouldHaveLength, 1)
+
+		// test get block with page size = 2
+		res, err = getJSON("v3/block/%v/%v?page=1&size=2", dbID, blockHash)
+		So(err, ShouldBeNil)
+		So(ensureSuccess(res.ArrayOfObjects("block", "queries")), ShouldHaveLength, 2)
+
+		// test get block with page size = 1, page = 2
+		res, err = getJSON("v3/block/%v/%v?page=2&size=1", dbID, blockHash)
 		So(err, ShouldBeNil)
-		So(ensureSuccess(res.Interface()), ShouldResemble, byHeightBlockResult)
+		So(ensureSuccess(res.ArrayOfObjects("block", "queries")), ShouldHaveLength, 1)
 
 		// test get block by hash using v1 version, returns ack hashes as queries
 		res, err = getJSON("v1/block/%v/%v", dbID, blockHash)
diff --git a/codecov.yml b/codecov.yml
index f663a9238..b223a6cc2 100644
--- a/codecov.yml
+++ b/codecov.yml
@@ -24,7 +24,7 @@ parsers:
 
 comment:
   layout: "header, diff"
-  behavior: new
+  behavior: default
   require_changes: no
 
 ignore:
diff --git a/types/request_type.go b/types/request_type.go
index bf280a2f0..241d7c982 100644
--- a/types/request_type.go
+++ b/types/request_type.go
@@ -36,8 +36,8 @@ const (
 	ReadQuery QueryType = iota
 	// WriteQuery defines a write query type.
 	WriteQuery
-	// NumberOfPerm defines the number of query type.
-	NumberOfPerm
+	// NumberOfQueryType defines the number of query type.
+	NumberOfQueryType
 )
 
 // NamedArg defines the named argument structure for database.