diff --git a/expression/bench_test.go b/expression/bench_test.go
index ba6c64e32a432..4c1a5c11a4e02 100644
--- a/expression/bench_test.go
+++ b/expression/bench_test.go
@@ -661,7 +661,7 @@ func genVecExprBenchCase(ctx sessionctx.Context, funcName string, testCase vecEx
 		panic(err)
 	}
 
-	output = chunk.New([]*types.FieldType{eType2FieldType(testCase.retEvalType)}, 1024, 1024)
+	output = chunk.New([]*types.FieldType{eType2FieldType(expr.GetType().EvalType())}, 1024, 1024)
 	return expr, fts, input, output
 }
 
@@ -681,7 +681,7 @@ func testVectorizedEvalOneVec(c *C, vecExprCases vecExprBenchCases) {
 			c.Assert(evalOneColumn(ctx, expr, it, output2, 0), IsNil, Commentf("func: %v, case: %+v", funcName, testCase))
 
 			c1, c2 := output.Column(0), output2.Column(0)
-			switch testCase.retEvalType {
+			switch expr.GetType().EvalType() {
 			case types.ETInt:
 				for i := 0; i < input.NumRows(); i++ {
 					c.Assert(c1.IsNull(i), Equals, c2.IsNull(i), commentf(i))
diff --git a/expression/builtin_time_vec.go b/expression/builtin_time_vec.go
index 9dcb5f30faaaf..19e714e8e3d04 100644
--- a/expression/builtin_time_vec.go
+++ b/expression/builtin_time_vec.go
@@ -176,11 +176,86 @@ func (b *builtinStringStringTimeDiffSig) vecEvalDuration(input *chunk.Chunk, res
 }
 
 func (b *builtinDayNameSig) vectorized() bool {
-	return false
+	return true
+}
+
+func (b *builtinDayNameSig) vecEvalIndex(input *chunk.Chunk, apply func(i, res int), applyNull func(i int)) error {
+	n := input.NumRows()
+	buf, err := b.bufAllocator.get(types.ETDatetime, n)
+	if err != nil {
+		return err
+	}
+	defer b.bufAllocator.put(buf)
+	if err := b.args[0].VecEvalTime(b.ctx, input, buf); err != nil {
+		return err
+	}
+
+	ds := buf.Times()
+	for i := 0; i < n; i++ {
+		if buf.IsNull(i) {
+			applyNull(i)
+			continue
+		}
+		if ds[i].InvalidZero() {
+			if err := handleInvalidTimeError(b.ctx, types.ErrIncorrectDatetimeValue.GenWithStackByArgs(ds[i].String())); err != nil {
+				return err
+			}
+			applyNull(i)
+			continue
+		}
+		// Monday is 0, ... Sunday = 6 in MySQL
+		// but in go, Sunday is 0, ... Saturday is 6
+		// we will do a conversion.
+		res := (int(ds[i].Time.Weekday()) + 6) % 7
+		apply(i, res)
+	}
+	return nil
+}
+
+// evalString evals a builtinDayNameSig.
+// See https://dev.mysql.com/doc/refman/5.7/en/date-and-time-functions.html#function_dayname
+func (b *builtinDayNameSig) vecEvalString(input *chunk.Chunk, result *chunk.Column) error {
+	n := input.NumRows()
+	result.ReserveString(n)
+
+	return b.vecEvalIndex(input,
+		func(i, res int) {
+			result.AppendString(types.WeekdayNames[res])
+		},
+		func(i int) {
+			result.AppendNull()
+		},
+	)
+}
+
+func (b *builtinDayNameSig) vecEvalReal(input *chunk.Chunk, result *chunk.Column) error {
+	n := input.NumRows()
+	result.ResizeFloat64(n, false)
+	f64s := result.Float64s()
+
+	return b.vecEvalIndex(input,
+		func(i, res int) {
+			f64s[i] = float64(res)
+		},
+		func(i int) {
+			result.SetNull(i, true)
+		},
+	)
 }
 
 func (b *builtinDayNameSig) vecEvalInt(input *chunk.Chunk, result *chunk.Column) error {
-	return errors.Errorf("not implemented")
+	n := input.NumRows()
+	result.ResizeInt64(n, false)
+	i64s := result.Int64s()
+
+	return b.vecEvalIndex(input,
+		func(i, res int) {
+			i64s[i] = int64(res)
+		},
+		func(i int) {
+			result.SetNull(i, true)
+		},
+	)
 }
 
 func (b *builtinWeekDaySig) vectorized() bool {
diff --git a/expression/builtin_time_vec_test.go b/expression/builtin_time_vec_test.go
index c346fbc3903fb..0a7def873677b 100644
--- a/expression/builtin_time_vec_test.go
+++ b/expression/builtin_time_vec_test.go
@@ -161,6 +161,11 @@ var vecBuiltinTimeCases = map[string][]vecExprBenchCase{
 	ast.DayOfMonth: {
 		{retEvalType: types.ETInt, childrenTypes: []types.EvalType{types.ETDatetime}},
 	},
+	ast.DayName: {
+		{retEvalType: types.ETString, childrenTypes: []types.EvalType{types.ETDatetime}},
+		{retEvalType: types.ETInt, childrenTypes: []types.EvalType{types.ETDatetime}},
+		{retEvalType: types.ETReal, childrenTypes: []types.EvalType{types.ETDatetime}},
+	},
 	ast.UTCDate: {
 		{retEvalType: types.ETDatetime},
 	},