diff --git a/executor/analyze.go b/executor/analyze.go
index 7158425d5a430..b0568abefd789 100644
--- a/executor/analyze.go
+++ b/executor/analyze.go
@@ -965,7 +965,9 @@ func (e *AnalyzeFastExec) handleSampTasks(bo *tikv.Backoffer, workID int, err *e
 			if *err != nil {
 				return
 			}
-			kvMap[string(iter.Key())] = iter.Value()
+			if iter.Valid() {
+				kvMap[string(iter.Key())] = iter.Value()
+			}
 		}
 
 		*err = e.handleBatchSeekResponse(kvMap)
diff --git a/executor/analyze_test.go b/executor/analyze_test.go
index 3216e294f5838..ab4ef000fde30 100644
--- a/executor/analyze_test.go
+++ b/executor/analyze_test.go
@@ -229,7 +229,7 @@ func (s *testSuite1) TestFastAnalyze(c *C) {
 	dom, err = session.BootstrapSession(store)
 	c.Assert(err, IsNil)
 	tk := testkit.NewTestKit(c, store)
-	executor.MaxSampleSize = 1000
+	executor.MaxSampleSize = 6
 	executor.RandSeed = 123
 
 	tk.MustExec("use test")
@@ -241,12 +241,12 @@ func (s *testSuite1) TestFastAnalyze(c *C) {
 	c.Assert(err, IsNil)
 	tid := tblInfo.Meta().ID
 
-	// construct 5 regions split by {600, 1200, 1800, 2400}
-	splitKeys := generateTableSplitKeyForInt(tid, []int{600, 1200, 1800, 2400})
+	// construct 6 regions split by {10, 20, 30, 40, 50}
+	splitKeys := generateTableSplitKeyForInt(tid, []int{10, 20, 30, 40, 50})
 	manipulateCluster(cluster, splitKeys)
 
-	for i := 0; i < 3000; i++ {
-		tk.MustExec(fmt.Sprintf(`insert into t values (%d, %d, "char")`, i, i))
+	for i := 0; i < 20; i++ {
+		tk.MustExec(fmt.Sprintf(`insert into t values (%d, %d, "char")`, i*3, i*3))
 	}
 	tk.MustExec("analyze table t with 5 buckets")
 
@@ -255,27 +255,21 @@ func (s *testSuite1) TestFastAnalyze(c *C) {
 	c.Assert(err, IsNil)
 	tableInfo := table.Meta()
 	tbl := dom.StatsHandle().GetTableStats(tableInfo)
-	c.Assert(tbl.String(), Equals, "Table:41 Count:3000\n"+
-		"column:1 ndv:3000 totColSize:0\n"+
-		"num: 603 lower_bound: 0 upper_bound: 658 repeats: 1\n"+
-		"num: 603 lower_bound: 663 upper_bound: 1248 repeats: 1\n"+
-		"num: 603 lower_bound: 1250 upper_bound: 1823 repeats: 1\n"+
-		"num: 603 lower_bound: 1830 upper_bound: 2379 repeats: 1\n"+
-		"num: 588 lower_bound: 2380 upper_bound: 2998 repeats: 1\n"+
-		"column:2 ndv:3000 totColSize:0\n"+
-		"num: 603 lower_bound: 0 upper_bound: 658 repeats: 1\n"+
-		"num: 603 lower_bound: 663 upper_bound: 1248 repeats: 1\n"+
-		"num: 603 lower_bound: 1250 upper_bound: 1823 repeats: 1\n"+
-		"num: 603 lower_bound: 1830 upper_bound: 2379 repeats: 1\n"+
-		"num: 588 lower_bound: 2380 upper_bound: 2998 repeats: 1\n"+
-		"column:3 ndv:1 totColSize:12000\n"+
-		"num: 3000 lower_bound: char upper_bound: char repeats: 3000\n"+
-		"index:1 ndv:3000\n"+
-		"num: 603 lower_bound: 0 upper_bound: 658 repeats: 1\n"+
-		"num: 603 lower_bound: 663 upper_bound: 1248 repeats: 1\n"+
-		"num: 603 lower_bound: 1250 upper_bound: 1823 repeats: 1\n"+
-		"num: 603 lower_bound: 1830 upper_bound: 2379 repeats: 1\n"+
-		"num: 588 lower_bound: 2380 upper_bound: 2998 repeats: 1")
+	c.Assert(tbl.String(), Equals, "Table:41 Count:20\n"+
+		"column:1 ndv:20 totColSize:0\n"+
+		"num: 6 lower_bound: 3 upper_bound: 15 repeats: 1\n"+
+		"num: 7 lower_bound: 18 upper_bound: 33 repeats: 1\n"+
+		"num: 7 lower_bound: 39 upper_bound: 57 repeats: 1\n"+
+		"column:2 ndv:20 totColSize:0\n"+
+		"num: 6 lower_bound: 3 upper_bound: 15 repeats: 1\n"+
+		"num: 7 lower_bound: 18 upper_bound: 33 repeats: 1\n"+
+		"num: 7 lower_bound: 39 upper_bound: 57 repeats: 1\n"+
+		"column:3 ndv:1 totColSize:72\n"+
+		"num: 20 lower_bound: char upper_bound: char repeats: 18\n"+
+		"index:1 ndv:20\n"+
+		"num: 6 lower_bound: 3 upper_bound: 15 repeats: 1\n"+
+		"num: 7 lower_bound: 18 upper_bound: 33 repeats: 1\n"+
+		"num: 7 lower_bound: 39 upper_bound: 57 repeats: 1")
 
 	// Test CM Sketch built from fast analyze.
 	tk.MustExec("create table t1(a int, b int, index idx(a, b))")