From ded1c4dd2cff15aefe94113af06384c3d1eb3f3e Mon Sep 17 00:00:00 2001
From: Yuanjia Zhang <zhangyuanjia@pingcap.com>
Date: Mon, 22 Jul 2019 13:46:14 +0800
Subject: [PATCH 01/17] add vectorized API for column

---
 util/chunk/chunk.go  |  12 ++--
 util/chunk/column.go | 136 +++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 142 insertions(+), 6 deletions(-)

diff --git a/util/chunk/chunk.go b/util/chunk/chunk.go
index 66e88d94fddea..2611927c4f384 100644
--- a/util/chunk/chunk.go
+++ b/util/chunk/chunk.go
@@ -66,12 +66,7 @@ func New(fields []*types.FieldType, cap, maxChunkSize int) *Chunk {
 	}
 
 	for _, f := range fields {
-		elemLen := getFixedLen(f)
-		if elemLen == varElemLen {
-			chk.columns = append(chk.columns, newVarLenColumn(chk.capacity, nil))
-		} else {
-			chk.columns = append(chk.columns, newFixedLenColumn(elemLen, chk.capacity))
-		}
+		chk.columns = append(chk.columns, NewColumn(f, chk.capacity))
 	}
 
 	return chk
@@ -555,6 +550,11 @@ func (c *Chunk) AppendDatum(colIdx int, d *types.Datum) {
 	}
 }
 
+// Column returns the specific column.
+func (c *Chunk) Column(colID int) *Column {
+	return c.columns[colID]
+}
+
 func writeTime(buf []byte, t types.Time) {
 	binary.BigEndian.PutUint16(buf, uint16(t.Time.Year()))
 	buf[2] = uint8(t.Time.Month())
diff --git a/util/chunk/column.go b/util/chunk/column.go
index d1ff51f803200..35fb743b6ea85 100644
--- a/util/chunk/column.go
+++ b/util/chunk/column.go
@@ -14,10 +14,12 @@
 package chunk
 
 import (
+	"reflect"
 	"unsafe"
 
 	"github.com/pingcap/tidb/types"
 	"github.com/pingcap/tidb/types/json"
+	"github.com/pingcap/tidb/util/hack"
 )
 
 // AppendDuration appends a duration value into this Column.
@@ -57,6 +59,16 @@ type Column struct {
 	elemBuf    []byte
 }
 
+// NewColumn creates a new column with the specific length and capacity.
+func NewColumn(ft *types.FieldType, cap int) *Column {
+	typeSize := getFixedLen(ft)
+	if typeSize == varElemLen {
+		return newFixedLenColumn(typeSize, cap)
+	} else {
+		return newVarLenColumn(cap, nil)
+	}
+}
+
 func (c *Column) isFixed() bool {
 	return c.elemBuf != nil
 }
@@ -190,3 +202,127 @@ func (c *Column) AppendTime(t types.Time) {
 	writeTime(c.elemBuf, t)
 	c.finishAppendFixed()
 }
+
+const (
+	sizeInt64     = int(unsafe.Sizeof(int64(0)))
+	sizeUint64    = int(unsafe.Sizeof(uint64(0)))
+	sizeFloat32   = int(unsafe.Sizeof(float32(0)))
+	sizeFloat64   = int(unsafe.Sizeof(float64(0)))
+	sizeTime      = int(unsafe.Sizeof(types.Time{}))
+	sizeDuration  = int(unsafe.Sizeof(types.Duration{}))
+	sizeMyDecimal = int(unsafe.Sizeof(types.MyDecimal{}))
+)
+
+// Int64s returns a int64 slice stored in this Column.
+func (c *Column) Int64s() []int64 {
+	h := (*reflect.SliceHeader)(unsafe.Pointer(&c.data))
+	var res []int64
+	s := (*reflect.SliceHeader)(unsafe.Pointer(&res))
+	s.Data = h.Data
+	s.Len = c.length
+	s.Cap = h.Cap / sizeInt64
+	return res
+}
+
+// Uint64s returns a uint64 slice stored in this Column.
+func (c *Column) Uint64s() []uint64 {
+	h := (*reflect.SliceHeader)(unsafe.Pointer(&c.data))
+	var res []uint64
+	s := (*reflect.SliceHeader)(unsafe.Pointer(&res))
+	s.Data = h.Data
+	s.Len = c.length
+	s.Cap = h.Cap / sizeUint64
+	return res
+}
+
+// Float32s returns a float32 slice stored in this Column.
+func (c *Column) Float32s() []float32 {
+	h := (*reflect.SliceHeader)(unsafe.Pointer(&c.data))
+	var res []float32
+	s := (*reflect.SliceHeader)(unsafe.Pointer(&res))
+	s.Data = h.Data
+	s.Len = c.length
+	s.Cap = h.Cap / sizeFloat32
+	return res
+}
+
+// Float64s returns a float64 slice stored in this Column.
+func (c *Column) Float64s() []float64 {
+	h := (*reflect.SliceHeader)(unsafe.Pointer(&c.data))
+	var res []float64
+	s := (*reflect.SliceHeader)(unsafe.Pointer(&res))
+	s.Data = h.Data
+	s.Len = c.length
+	s.Cap = h.Cap / sizeFloat64
+	return res
+}
+
+// Times returns a Time slice stored in this Column.
+func (c *Column) Times() []types.Time {
+	h := (*reflect.SliceHeader)(unsafe.Pointer(&c.data))
+	var res []types.Time
+	s := (*reflect.SliceHeader)(unsafe.Pointer(&res))
+	s.Data = h.Data
+	s.Len = c.length
+	s.Cap = h.Cap / sizeTime
+	return res
+}
+
+// Durations returns a Duration slice stored in this Column.
+func (c *Column) Durations() []types.Duration {
+	h := (*reflect.SliceHeader)(unsafe.Pointer(&c.data))
+	var res []types.Duration
+	s := (*reflect.SliceHeader)(unsafe.Pointer(&res))
+	s.Data = h.Data
+	s.Len = c.length
+	s.Cap = h.Cap / sizeDuration
+	return res
+}
+
+// MyDecimals returns a MyDecimal slice stored in this Column.
+func (c *Column) MyDecimals() []types.MyDecimal {
+	h := (*reflect.SliceHeader)(unsafe.Pointer(&c.data))
+	var res []types.MyDecimal
+	s := (*reflect.SliceHeader)(unsafe.Pointer(&res))
+	s.Data = h.Data
+	s.Len = c.length
+	s.Cap = h.Cap / sizeMyDecimal
+	return res
+}
+
+// GetString returns the string in the specific row.
+func (c *Column) GetString(rowID int) string {
+	return string(hack.String(c.data[c.offsets[rowID]:c.offsets[rowID+1]]))
+}
+
+// GetString returns the JSON in the specific row.
+func (c *Column) GetJSON(rowID int) json.BinaryJSON {
+	start := c.offsets[rowID]
+	return json.BinaryJSON{TypeCode: c.data[start], Value: c.data[start+1 : c.offsets[rowID+1]]}
+}
+
+// GetBytes returns the byte slice in the specific row.
+func (c *Column) GetBytes(rowID int) []byte {
+	return c.data[c.offsets[rowID]:c.offsets[rowID+1]]
+}
+
+// GetEnum returns the Enum in the specific row.
+func (c *Column) GetEnum(rowID int) types.Enum {
+	name, val := c.getNameValue(rowID)
+	return types.Enum{Name: name, Value: val}
+}
+
+// GetSet returns the Set in the specific row.
+func (c *Column) GetSet(rowID int) types.Set {
+	name, val := c.getNameValue(rowID)
+	return types.Set{Name: name, Value: val}
+}
+
+// GetString returns the byte slice in the specific row.
+func (c *Column) getNameValue(rowID int) (string, uint64) {
+	start, end := c.offsets[rowID], c.offsets[rowID+1]
+	if start == end {
+		return "", 0
+	}
+	return string(hack.String(c.data[start+8 : end])), *(*uint64)(unsafe.Pointer(&c.data[start]))
+}

From f4933a3eff39618c09d7256be5fab66de07c2cfc Mon Sep 17 00:00:00 2001
From: Yuanjia Zhang <zhangyuanjia@pingcap.com>
Date: Mon, 22 Jul 2019 14:25:11 +0800
Subject: [PATCH 02/17] add UT

---
 util/chunk/chunk.go       |  2 +-
 util/chunk/column.go      | 40 +++++++++++++++------------------------
 util/chunk/column_test.go | 34 +++++++++++++++++++++++++++++++++
 3 files changed, 50 insertions(+), 26 deletions(-)

diff --git a/util/chunk/chunk.go b/util/chunk/chunk.go
index 2611927c4f384..2b575259f46cb 100644
--- a/util/chunk/chunk.go
+++ b/util/chunk/chunk.go
@@ -471,7 +471,7 @@ func (c *Chunk) AppendUint64(colIdx int, u uint64) {
 
 // AppendFloat32 appends a float32 value to the chunk.
 func (c *Chunk) AppendFloat32(colIdx int, f float32) {
-	c.columns[colIdx].appendFloat32(f)
+	c.columns[colIdx].AppendFloat32(f)
 }
 
 // AppendFloat64 appends a float64 value to the chunk.
diff --git a/util/chunk/column.go b/util/chunk/column.go
index 35fb743b6ea85..d020313099362 100644
--- a/util/chunk/column.go
+++ b/util/chunk/column.go
@@ -15,6 +15,7 @@ package chunk
 
 import (
 	"reflect"
+	"time"
 	"unsafe"
 
 	"github.com/pingcap/tidb/types"
@@ -167,8 +168,8 @@ func (c *Column) AppendUint64(u uint64) {
 	c.finishAppendFixed()
 }
 
-// appendFloat32 appends a float32 value into this Column.
-func (c *Column) appendFloat32(f float32) {
+// AppendFloat32 appends a float32 value into this Column.
+func (c *Column) AppendFloat32(f float32) {
 	*(*float32)(unsafe.Pointer(&c.elemBuf[0])) = f
 	c.finishAppendFixed()
 }
@@ -213,7 +214,7 @@ const (
 	sizeMyDecimal = int(unsafe.Sizeof(types.MyDecimal{}))
 )
 
-// Int64s returns a int64 slice stored in this Column.
+// Int64s returns an int64 slice stored in this Column.
 func (c *Column) Int64s() []int64 {
 	h := (*reflect.SliceHeader)(unsafe.Pointer(&c.data))
 	var res []int64
@@ -257,28 +258,6 @@ func (c *Column) Float64s() []float64 {
 	return res
 }
 
-// Times returns a Time slice stored in this Column.
-func (c *Column) Times() []types.Time {
-	h := (*reflect.SliceHeader)(unsafe.Pointer(&c.data))
-	var res []types.Time
-	s := (*reflect.SliceHeader)(unsafe.Pointer(&res))
-	s.Data = h.Data
-	s.Len = c.length
-	s.Cap = h.Cap / sizeTime
-	return res
-}
-
-// Durations returns a Duration slice stored in this Column.
-func (c *Column) Durations() []types.Duration {
-	h := (*reflect.SliceHeader)(unsafe.Pointer(&c.data))
-	var res []types.Duration
-	s := (*reflect.SliceHeader)(unsafe.Pointer(&res))
-	s.Data = h.Data
-	s.Len = c.length
-	s.Cap = h.Cap / sizeDuration
-	return res
-}
-
 // MyDecimals returns a MyDecimal slice stored in this Column.
 func (c *Column) MyDecimals() []types.MyDecimal {
 	h := (*reflect.SliceHeader)(unsafe.Pointer(&c.data))
@@ -318,6 +297,17 @@ func (c *Column) GetSet(rowID int) types.Set {
 	return types.Set{Name: name, Value: val}
 }
 
+// GetTime returns the Time in the specific row.
+func (c *Column) GetTime(rowID int) types.Time {
+	return readTime(c.data[rowID*16:])
+}
+
+// GetDuration returns the Duration in the specific row.
+func (c *Column) GetDuration(rowID int, fillFsp int) types.Duration {
+	dur := *(*int64)(unsafe.Pointer(&c.data[rowID*8]))
+	return types.Duration{Duration: time.Duration(dur), Fsp: fillFsp}
+}
+
 // GetString returns the byte slice in the specific row.
 func (c *Column) getNameValue(rowID int) (string, uint64) {
 	start, end := c.offsets[rowID], c.offsets[rowID+1]
diff --git a/util/chunk/column_test.go b/util/chunk/column_test.go
index ff577fea30ac4..9ccda4998ef1d 100644
--- a/util/chunk/column_test.go
+++ b/util/chunk/column_test.go
@@ -14,7 +14,10 @@
 package chunk
 
 import (
+	"fmt"
 	"github.com/pingcap/check"
+	"github.com/pingcap/parser/mysql"
+	"github.com/pingcap/tidb/types"
 )
 
 func equalColumn(c1, c2 *Column) bool {
@@ -67,3 +70,34 @@ func (s *testChunkSuite) TestLargeStringColumnOffset(c *check.C) {
 	col.offsets[0] = 6 << 30
 	c.Check(col.offsets[0], check.Equals, int64(6<<30)) // test no overflow.
 }
+
+func (s *testChunkSuite) TestI64Column(c *check.C) {
+	chk := NewChunkWithCapacity([]*types.FieldType{types.NewFieldType(mysql.TypeLonglong)}, 1024)
+	col := chk.Column(0)
+	for i := 0; i < 1024; i++ {
+		col.AppendInt64(int64(i))
+	}
+
+	i64s := col.Int64s()
+	for i := 0; i < 1024; i++ {
+		c.Assert(i64s[i], check.Equals, int64(i))
+		i64s[i] ++
+	}
+
+	it := NewIterator4Chunk(chk)
+	var i int64
+	for row := it.Begin(); row != it.End(); row = it.Next() {
+		c.Assert(row.GetInt64(0), check.Equals, int64(i+1))
+		i++
+	}
+}
+
+func (s *testChunkSuite) TestStringColumn(c *check.C) {
+	col := NewColumn(types.NewFieldType(mysql.TypeVarString), 1024)
+	for i := 0; i < 1024; i++ {
+		col.AppendString(fmt.Sprintf("%v", i))
+	}
+	for i := 0; i < 1024; i++ {
+		c.Assert(col.GetString(i), check.Equals, fmt.Sprintf("%v", i))
+	}
+}

From ade0be884e867d15cc783e04a0e8e4d37d8fc3d8 Mon Sep 17 00:00:00 2001
From: Yuanjia Zhang <zhangyuanjia@pingcap.com>
Date: Mon, 22 Jul 2019 14:31:16 +0800
Subject: [PATCH 03/17] add UT

---
 util/chunk/column.go      |  4 ++--
 util/chunk/column_test.go | 42 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 44 insertions(+), 2 deletions(-)

diff --git a/util/chunk/column.go b/util/chunk/column.go
index d020313099362..ef5c0810775c5 100644
--- a/util/chunk/column.go
+++ b/util/chunk/column.go
@@ -64,9 +64,9 @@ type Column struct {
 func NewColumn(ft *types.FieldType, cap int) *Column {
 	typeSize := getFixedLen(ft)
 	if typeSize == varElemLen {
-		return newFixedLenColumn(typeSize, cap)
-	} else {
 		return newVarLenColumn(cap, nil)
+	} else {
+		return newFixedLenColumn(typeSize, cap)
 	}
 }
 
diff --git a/util/chunk/column_test.go b/util/chunk/column_test.go
index 9ccda4998ef1d..76ec9cbbbbc21 100644
--- a/util/chunk/column_test.go
+++ b/util/chunk/column_test.go
@@ -92,6 +92,48 @@ func (s *testChunkSuite) TestI64Column(c *check.C) {
 	}
 }
 
+func (s *testChunkSuite) TestF64Column(c *check.C) {
+	chk := NewChunkWithCapacity([]*types.FieldType{types.NewFieldType(mysql.TypeDouble)}, 1024)
+	col := chk.Column(0)
+	for i := 0; i < 1024; i++ {
+		col.AppendFloat64(float64(i))
+	}
+
+	f64s := col.Float64s()
+	for i := 0; i < 1024; i++ {
+		c.Assert(f64s[i], check.Equals, float64(i))
+		f64s[i] /= 2
+	}
+
+	it := NewIterator4Chunk(chk)
+	var i int64
+	for row := it.Begin(); row != it.End(); row = it.Next() {
+		c.Assert(row.GetFloat64(0), check.Equals, float64(i)/2)
+		i++
+	}
+}
+
+func (s *testChunkSuite) TestF32Column(c *check.C) {
+	chk := NewChunkWithCapacity([]*types.FieldType{types.NewFieldType(mysql.TypeFloat)}, 1024)
+	col := chk.Column(0)
+	for i := 0; i < 1024; i++ {
+		col.AppendFloat32(float32(i))
+	}
+
+	f32s := col.Float32s()
+	for i := 0; i < 1024; i++ {
+		c.Assert(f32s[i], check.Equals, float32(i))
+		f32s[i] /= 2
+	}
+
+	it := NewIterator4Chunk(chk)
+	var i int64
+	for row := it.Begin(); row != it.End(); row = it.Next() {
+		c.Assert(row.GetFloat32(0), check.Equals, float32(i)/2)
+		i++
+	}
+}
+
 func (s *testChunkSuite) TestStringColumn(c *check.C) {
 	col := NewColumn(types.NewFieldType(mysql.TypeVarString), 1024)
 	for i := 0; i < 1024; i++ {

From b6e29ad5810e40f38208b33eabb55bb3ab3c073b Mon Sep 17 00:00:00 2001
From: Yuanjia Zhang <zhangyuanjia@pingcap.com>
Date: Mon, 22 Jul 2019 14:48:03 +0800
Subject: [PATCH 04/17] add UT

---
 util/chunk/column_test.go | 49 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 49 insertions(+)

diff --git a/util/chunk/column_test.go b/util/chunk/column_test.go
index 76ec9cbbbbc21..b0abdf18dd330 100644
--- a/util/chunk/column_test.go
+++ b/util/chunk/column_test.go
@@ -134,6 +134,55 @@ func (s *testChunkSuite) TestF32Column(c *check.C) {
 	}
 }
 
+func (s *testChunkSuite) TestMyDecimal(c *check.C) {
+	chk := NewChunkWithCapacity([]*types.FieldType{types.NewFieldType(mysql.TypeNewDecimal)}, 1024)
+	col := chk.Column(0)
+	for i := 0; i < 1024; i++ {
+		d := new(types.MyDecimal)
+		if err := d.FromFloat64(float64(i) * 1.1); err != nil {
+			c.Fatal(err)
+		}
+		col.AppendMyDecimal(d)
+	}
+
+	ds := col.MyDecimals()
+	for i := 0; i < 1024; i++ {
+		d := new(types.MyDecimal)
+		if err := d.FromFloat64(float64(i) * 1.1); err != nil {
+			c.Fatal(err)
+		}
+		c.Assert(d.Compare(&ds[i]), check.Equals, 0)
+
+		if err := types.DecimalAdd(&ds[i], d, &ds[i]); err != nil {
+			c.Fatal(err)
+		}
+	}
+
+	it := NewIterator4Chunk(chk)
+	var i int64
+	for row := it.Begin(); row != it.End(); row = it.Next() {
+		d := new(types.MyDecimal)
+		if err := d.FromFloat64(float64(i) * 1.1 * 2); err != nil {
+			c.Fatal(err)
+		}
+
+		delta := new(types.MyDecimal)
+		if err := types.DecimalSub(d, row.GetMyDecimal(0), delta); err != nil {
+			c.Fatal(err)
+		}
+
+		fDelta, err := delta.ToFloat64()
+		if err != nil {
+			c.Fatal(err)
+		}
+		if fDelta > 0.0001 || fDelta < -0.0001 {
+			c.Fatal()
+		}
+
+		i++
+	}
+}
+
 func (s *testChunkSuite) TestStringColumn(c *check.C) {
 	col := NewColumn(types.NewFieldType(mysql.TypeVarString), 1024)
 	for i := 0; i < 1024; i++ {

From a993efd58c563c689e8b26139cbdb5fd9ad73f92 Mon Sep 17 00:00:00 2001
From: Yuanjia Zhang <zhangyuanjia@pingcap.com>
Date: Mon, 22 Jul 2019 15:00:13 +0800
Subject: [PATCH 05/17] add UT

---
 util/chunk/column_test.go | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/util/chunk/column_test.go b/util/chunk/column_test.go
index b0abdf18dd330..df5f91fb149a5 100644
--- a/util/chunk/column_test.go
+++ b/util/chunk/column_test.go
@@ -184,11 +184,17 @@ func (s *testChunkSuite) TestMyDecimal(c *check.C) {
 }
 
 func (s *testChunkSuite) TestStringColumn(c *check.C) {
-	col := NewColumn(types.NewFieldType(mysql.TypeVarString), 1024)
+	chk := NewChunkWithCapacity([]*types.FieldType{types.NewFieldType(mysql.TypeVarString)}, 1024)
+	col := chk.Column(0)
 	for i := 0; i < 1024; i++ {
-		col.AppendString(fmt.Sprintf("%v", i))
+		col.AppendString(fmt.Sprintf("%v", i*i))
 	}
-	for i := 0; i < 1024; i++ {
-		c.Assert(col.GetString(i), check.Equals, fmt.Sprintf("%v", i))
+
+	it := NewIterator4Chunk(chk)
+	var i int
+	for row := it.Begin(); row != it.End(); row = it.Next() {
+		c.Assert(row.GetString(0), check.Equals, fmt.Sprintf("%v", i*i))
+		c.Assert(col.GetString(i), check.Equals, fmt.Sprintf("%v", i*i))
+		i++
 	}
 }

From dbb140fa48f86a4fae2b3bd728916b037f5f0fdc Mon Sep 17 00:00:00 2001
From: Yuanjia Zhang <zhangyuanjia@pingcap.com>
Date: Mon, 22 Jul 2019 15:07:31 +0800
Subject: [PATCH 06/17] add UT

---
 util/chunk/column.go      |  5 +++++
 util/chunk/column_test.go | 20 ++++++++++++++++++++
 2 files changed, 25 insertions(+)

diff --git a/util/chunk/column.go b/util/chunk/column.go
index ef5c0810775c5..ba362ea9a0967 100644
--- a/util/chunk/column.go
+++ b/util/chunk/column.go
@@ -49,6 +49,11 @@ func (c *Column) AppendJSON(j json.BinaryJSON) {
 	c.finishAppendVar()
 }
 
+// AppendJSON appends a Set value into this Column.
+func (c *Column) AppendSet(set types.Set) {
+	c.appendNameValue(set.Name, set.Value)
+}
+
 // Column stores one column of data in Apache Arrow format.
 // See https://arrow.apache.org/docs/memory_layout.html
 type Column struct {
diff --git a/util/chunk/column_test.go b/util/chunk/column_test.go
index df5f91fb149a5..0ea6c20265cee 100644
--- a/util/chunk/column_test.go
+++ b/util/chunk/column_test.go
@@ -198,3 +198,23 @@ func (s *testChunkSuite) TestStringColumn(c *check.C) {
 		i++
 	}
 }
+
+func (s *testChunkSuite) TestSetColumn(c *check.C) {
+	chk := NewChunkWithCapacity([]*types.FieldType{types.NewFieldType(mysql.TypeSet)}, 1024)
+	col := chk.Column(0)
+	for i := 0; i < 1024; i++ {
+		col.AppendSet(types.Set{Name: fmt.Sprintf("%v", i), Value: uint64(i)})
+	}
+
+	it := NewIterator4Chunk(chk)
+	var i int
+	for row := it.Begin(); row != it.End(); row = it.Next() {
+		s1 := col.GetSet(i)
+		s2 := row.GetSet(0)
+		c.Assert(s1.Name, check.Equals, s2.Name)
+		c.Assert(s1.Value, check.Equals, s2.Value)
+		c.Assert(s1.Name, check.Equals, fmt.Sprintf("%v", i))
+		c.Assert(s1.Value, check.Equals, uint64(i))
+		i++
+	}
+}

From 31906e7cdde92cccaea16eea81765bf3ee543bca Mon Sep 17 00:00:00 2001
From: Yuanjia Zhang <zhangyuanjia@pingcap.com>
Date: Mon, 22 Jul 2019 15:19:47 +0800
Subject: [PATCH 07/17] add UT for JSON

---
 util/chunk/column_test.go | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/util/chunk/column_test.go b/util/chunk/column_test.go
index 0ea6c20265cee..ac116efed029b 100644
--- a/util/chunk/column_test.go
+++ b/util/chunk/column_test.go
@@ -18,6 +18,7 @@ import (
 	"github.com/pingcap/check"
 	"github.com/pingcap/parser/mysql"
 	"github.com/pingcap/tidb/types"
+	"github.com/pingcap/tidb/types/json"
 )
 
 func equalColumn(c1, c2 *Column) bool {
@@ -218,3 +219,24 @@ func (s *testChunkSuite) TestSetColumn(c *check.C) {
 		i++
 	}
 }
+
+func (s *testChunkSuite) TestJSONColumn(c *check.C) {
+	chk := NewChunkWithCapacity([]*types.FieldType{types.NewFieldType(mysql.TypeJSON)}, 1024)
+	col := chk.Column(0)
+	for i := 0; i < 1024; i++ {
+		j := new(json.BinaryJSON)
+		if err := j.UnmarshalJSON([]byte(fmt.Sprintf(`{"%v":%v}`, i, i))); err != nil {
+			c.Fatal(err)
+		}
+		col.AppendJSON(*j)
+	}
+
+	it := NewIterator4Chunk(chk)
+	var i int
+	for row := it.Begin(); row != it.End(); row = it.Next() {
+		j1 := col.GetJSON(i)
+		j2 := row.GetJSON(0)
+		c.Assert(j1.String(), check.Equals, j2.String())
+		i++
+	}
+}

From 70f7523ab6f31b967861bd9aba68c85d23ad7555 Mon Sep 17 00:00:00 2001
From: Yuanjia Zhang <zhangyuanjia@pingcap.com>
Date: Mon, 22 Jul 2019 15:25:27 +0800
Subject: [PATCH 08/17] add UT for Time

---
 util/chunk/column.go      |  2 --
 util/chunk/column_test.go | 19 +++++++++++++++++++
 2 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/util/chunk/column.go b/util/chunk/column.go
index ba362ea9a0967..3ff54877d7f52 100644
--- a/util/chunk/column.go
+++ b/util/chunk/column.go
@@ -214,8 +214,6 @@ const (
 	sizeUint64    = int(unsafe.Sizeof(uint64(0)))
 	sizeFloat32   = int(unsafe.Sizeof(float32(0)))
 	sizeFloat64   = int(unsafe.Sizeof(float64(0)))
-	sizeTime      = int(unsafe.Sizeof(types.Time{}))
-	sizeDuration  = int(unsafe.Sizeof(types.Duration{}))
 	sizeMyDecimal = int(unsafe.Sizeof(types.MyDecimal{}))
 )
 
diff --git a/util/chunk/column_test.go b/util/chunk/column_test.go
index ac116efed029b..4960a02347dc5 100644
--- a/util/chunk/column_test.go
+++ b/util/chunk/column_test.go
@@ -19,6 +19,7 @@ import (
 	"github.com/pingcap/parser/mysql"
 	"github.com/pingcap/tidb/types"
 	"github.com/pingcap/tidb/types/json"
+	"time"
 )
 
 func equalColumn(c1, c2 *Column) bool {
@@ -240,3 +241,21 @@ func (s *testChunkSuite) TestJSONColumn(c *check.C) {
 		i++
 	}
 }
+
+func (s *testChunkSuite) TestTimeColumn(c *check.C) {
+	chk := NewChunkWithCapacity([]*types.FieldType{types.NewFieldType(mysql.TypeDatetime)}, 1024)
+	col := chk.Column(0)
+	for i := 0; i < 1024; i++ {
+		col.AppendTime(types.CurrentTime(mysql.TypeDatetime))
+		time.Sleep(time.Millisecond / 10)
+	}
+
+	it := NewIterator4Chunk(chk)
+	var i int
+	for row := it.Begin(); row != it.End(); row = it.Next() {
+		j1 := col.GetTime(i)
+		j2 := row.GetTime(0)
+		c.Assert(j1.Compare(j2), check.Equals, 0)
+		i++
+	}
+}

From 6703a161e77f4ac351a73c77a2f0ed6ca891a117 Mon Sep 17 00:00:00 2001
From: Yuanjia Zhang <zhangyuanjia@pingcap.com>
Date: Mon, 22 Jul 2019 15:27:17 +0800
Subject: [PATCH 09/17] add UT for Duration

---
 util/chunk/column_test.go | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/util/chunk/column_test.go b/util/chunk/column_test.go
index 4960a02347dc5..54a5e51d52edc 100644
--- a/util/chunk/column_test.go
+++ b/util/chunk/column_test.go
@@ -259,3 +259,20 @@ func (s *testChunkSuite) TestTimeColumn(c *check.C) {
 		i++
 	}
 }
+
+func (s *testChunkSuite) TestDurationColumn(c *check.C) {
+	chk := NewChunkWithCapacity([]*types.FieldType{types.NewFieldType(mysql.TypeDuration)}, 1024)
+	col := chk.Column(0)
+	for i := 0; i < 1024; i++ {
+		col.AppendDuration(types.Duration{Duration: time.Second * time.Duration(i)})
+	}
+
+	it := NewIterator4Chunk(chk)
+	var i int
+	for row := it.Begin(); row != it.End(); row = it.Next() {
+		j1 := col.GetDuration(i, 0)
+		j2 := row.GetDuration(0, 0)
+		c.Assert(j1.Compare(j2), check.Equals, 0)
+		i++
+	}
+}

From 93795b3760836c83599bf842522ee8addbe6486e Mon Sep 17 00:00:00 2001
From: Yuanjia Zhang <zhangyuanjia@pingcap.com>
Date: Mon, 22 Jul 2019 15:30:31 +0800
Subject: [PATCH 10/17] add UT for TestEnumColumn

---
 util/chunk/column.go      |  5 +++++
 util/chunk/column_test.go | 20 ++++++++++++++++++++
 2 files changed, 25 insertions(+)

diff --git a/util/chunk/column.go b/util/chunk/column.go
index 3ff54877d7f52..a6a6f294a1f13 100644
--- a/util/chunk/column.go
+++ b/util/chunk/column.go
@@ -209,6 +209,11 @@ func (c *Column) AppendTime(t types.Time) {
 	c.finishAppendFixed()
 }
 
+// AppendEnum appends a Enum value into this Column.
+func (c *Column) AppendEnum(enum types.Enum) {
+	c.appendNameValue(enum.Name, enum.Value)
+}
+
 const (
 	sizeInt64     = int(unsafe.Sizeof(int64(0)))
 	sizeUint64    = int(unsafe.Sizeof(uint64(0)))
diff --git a/util/chunk/column_test.go b/util/chunk/column_test.go
index 54a5e51d52edc..289c6fff3a3c3 100644
--- a/util/chunk/column_test.go
+++ b/util/chunk/column_test.go
@@ -276,3 +276,23 @@ func (s *testChunkSuite) TestDurationColumn(c *check.C) {
 		i++
 	}
 }
+
+func (s *testChunkSuite) TestEnumColumn(c *check.C) {
+	chk := NewChunkWithCapacity([]*types.FieldType{types.NewFieldType(mysql.TypeEnum)}, 1024)
+	col := chk.Column(0)
+	for i := 0; i < 1024; i++ {
+		col.AppendEnum(types.Enum{Name: fmt.Sprintf("%v", i), Value: uint64(i)})
+	}
+
+	it := NewIterator4Chunk(chk)
+	var i int
+	for row := it.Begin(); row != it.End(); row = it.Next() {
+		s1 := col.GetEnum(i)
+		s2 := row.GetEnum(0)
+		c.Assert(s1.Name, check.Equals, s2.Name)
+		c.Assert(s1.Value, check.Equals, s2.Value)
+		c.Assert(s1.Name, check.Equals, fmt.Sprintf("%v", i))
+		c.Assert(s1.Value, check.Equals, uint64(i))
+		i++
+	}
+}

From 3dc43895bfca724b866f894ceba2c7462d2482ef Mon Sep 17 00:00:00 2001
From: Yuanjia Zhang <zhangyuanjia@pingcap.com>
Date: Mon, 22 Jul 2019 15:33:42 +0800
Subject: [PATCH 11/17] add UT for IsNull

---
 util/chunk/chunk.go       |  8 ++++----
 util/chunk/chunk_util.go  |  6 +++---
 util/chunk/column.go      |  3 ++-
 util/chunk/column_test.go | 24 ++++++++++++++++++++++++
 util/chunk/mutrow.go      |  4 ++--
 util/chunk/row.go         |  2 +-
 6 files changed, 36 insertions(+), 11 deletions(-)

diff --git a/util/chunk/chunk.go b/util/chunk/chunk.go
index 2b575259f46cb..4217d64f1595a 100644
--- a/util/chunk/chunk.go
+++ b/util/chunk/chunk.go
@@ -305,7 +305,7 @@ func (c *Chunk) AppendRow(row Row) {
 func (c *Chunk) AppendPartialRow(colIdx int, row Row) {
 	for i, rowCol := range row.c.columns {
 		chkCol := c.columns[colIdx+i]
-		chkCol.appendNullBitmap(!rowCol.isNull(row.idx))
+		chkCol.appendNullBitmap(!rowCol.IsNull(row.idx))
 		if rowCol.isFixed() {
 			elemLen := len(rowCol.elemBuf)
 			offset := row.idx * elemLen
@@ -333,7 +333,7 @@ func (c *Chunk) PreAlloc(row Row) (rowIdx uint32) {
 	rowIdx = uint32(c.NumRows())
 	for i, srcCol := range row.c.columns {
 		dstCol := c.columns[i]
-		dstCol.appendNullBitmap(!srcCol.isNull(row.idx))
+		dstCol.appendNullBitmap(!srcCol.IsNull(row.idx))
 		elemLen := len(srcCol.elemBuf)
 		if !srcCol.isFixed() {
 			elemLen = int(srcCol.offsets[row.idx+1] - srcCol.offsets[row.idx])
@@ -416,7 +416,7 @@ func (c *Chunk) Append(other *Chunk, begin, end int) {
 			}
 		}
 		for i := begin; i < end; i++ {
-			dst.appendNullBitmap(!src.isNull(i))
+			dst.appendNullBitmap(!src.IsNull(i))
 			dst.length++
 		}
 	}
@@ -434,7 +434,7 @@ func (c *Chunk) TruncateTo(numRows int) {
 			col.offsets = col.offsets[:numRows+1]
 		}
 		for i := numRows; i < col.length; i++ {
-			if col.isNull(i) {
+			if col.IsNull(i) {
 				col.nullCount--
 			}
 		}
diff --git a/util/chunk/chunk_util.go b/util/chunk/chunk_util.go
index 9bc6dddb73fda..be15dafe44a87 100644
--- a/util/chunk/chunk_util.go
+++ b/util/chunk/chunk_util.go
@@ -47,7 +47,7 @@ func copySelectedInnerRows(innerColOffset, outerColOffset int, src *Chunk, selec
 				if !selected[i] {
 					continue
 				}
-				dstCol.appendNullBitmap(!srcCol.isNull(i))
+				dstCol.appendNullBitmap(!srcCol.IsNull(i))
 				dstCol.length++
 
 				elemLen := len(srcCol.elemBuf)
@@ -59,7 +59,7 @@ func copySelectedInnerRows(innerColOffset, outerColOffset int, src *Chunk, selec
 				if !selected[i] {
 					continue
 				}
-				dstCol.appendNullBitmap(!srcCol.isNull(i))
+				dstCol.appendNullBitmap(!srcCol.IsNull(i))
 				dstCol.length++
 
 				start, end := srcCol.offsets[i], srcCol.offsets[i+1]
@@ -86,7 +86,7 @@ func copyOuterRows(innerColOffset, outerColOffset int, src *Chunk, numRows int,
 	}
 	for i, srcCol := range srcCols {
 		dstCol := dst.columns[outerColOffset+i]
-		dstCol.appendMultiSameNullBitmap(!srcCol.isNull(row.idx), numRows)
+		dstCol.appendMultiSameNullBitmap(!srcCol.IsNull(row.idx), numRows)
 		dstCol.length += numRows
 		if srcCol.isFixed() {
 			elemLen := len(srcCol.elemBuf)
diff --git a/util/chunk/column.go b/util/chunk/column.go
index a6a6f294a1f13..9e1ec5a8eaae3 100644
--- a/util/chunk/column.go
+++ b/util/chunk/column.go
@@ -91,7 +91,8 @@ func (c *Column) Reset() {
 	c.data = c.data[:0]
 }
 
-func (c *Column) isNull(rowIdx int) bool {
+// IsNull returns if this row is null.
+func (c *Column) IsNull(rowIdx int) bool {
 	nullByte := c.nullBitmap[rowIdx/8]
 	return nullByte&(1<<(uint(rowIdx)&7)) == 0
 }
diff --git a/util/chunk/column_test.go b/util/chunk/column_test.go
index 289c6fff3a3c3..6f667ce03a14e 100644
--- a/util/chunk/column_test.go
+++ b/util/chunk/column_test.go
@@ -296,3 +296,27 @@ func (s *testChunkSuite) TestEnumColumn(c *check.C) {
 		i++
 	}
 }
+
+func (s *testChunkSuite) TestNullsColumn(c *check.C) {
+	chk := NewChunkWithCapacity([]*types.FieldType{types.NewFieldType(mysql.TypeLonglong)}, 1024)
+	col := chk.Column(0)
+	for i := 0; i < 1024; i++ {
+		if i%2 == 0 {
+			col.AppendNull()
+			continue
+		}
+		col.AppendInt64(int64(i))
+	}
+
+	it := NewIterator4Chunk(chk)
+	var i int
+	for row := it.Begin(); row != it.End(); row = it.Next() {
+		if i%2 == 0 {
+			c.Assert(row.IsNull(0), check.Equals, true)
+			c.Assert(col.IsNull(i), check.Equals, true)
+		} else {
+			c.Assert(row.GetInt64(0), check.Equals, int64(i))
+		}
+		i++
+	}
+}
diff --git a/util/chunk/mutrow.go b/util/chunk/mutrow.go
index aa36326559930..b0bddc18f3029 100644
--- a/util/chunk/mutrow.go
+++ b/util/chunk/mutrow.go
@@ -203,7 +203,7 @@ func makeMutRowBytesColumn(bin []byte) *Column {
 func (mr MutRow) SetRow(row Row) {
 	for colIdx, rCol := range row.c.columns {
 		mrCol := mr.c.columns[colIdx]
-		if rCol.isNull(row.idx) {
+		if rCol.IsNull(row.idx) {
 			mrCol.nullBitmap[0] = 0
 			continue
 		}
@@ -351,7 +351,7 @@ func setMutRowJSON(col *Column, j json.BinaryJSON) {
 func (mr MutRow) ShallowCopyPartialRow(colIdx int, row Row) {
 	for i, srcCol := range row.c.columns {
 		dstCol := mr.c.columns[colIdx+i]
-		if !srcCol.isNull(row.idx) {
+		if !srcCol.IsNull(row.idx) {
 			// MutRow only contains one row, so we can directly set the whole byte.
 			dstCol.nullBitmap[0] = 1
 		} else {
diff --git a/util/chunk/row.go b/util/chunk/row.go
index 0d282558fc0e1..b4c22d6b02210 100644
--- a/util/chunk/row.go
+++ b/util/chunk/row.go
@@ -220,5 +220,5 @@ func (r Row) GetDatum(colIdx int, tp *types.FieldType) types.Datum {
 
 // IsNull returns if the datum in the chunk.Row is null.
 func (r Row) IsNull(colIdx int) bool {
-	return r.c.columns[colIdx].isNull(r.idx)
+	return r.c.columns[colIdx].IsNull(r.idx)
 }

From e59ac63ec7b6232360d5ed726aba07ef2650cc19 Mon Sep 17 00:00:00 2001
From: Yuanjia Zhang <zhangyuanjia@pingcap.com>
Date: Mon, 22 Jul 2019 15:57:43 +0800
Subject: [PATCH 12/17] refmt

---
 util/chunk/column_test.go | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/util/chunk/column_test.go b/util/chunk/column_test.go
index 6f667ce03a14e..59b709a92ac95 100644
--- a/util/chunk/column_test.go
+++ b/util/chunk/column_test.go
@@ -15,11 +15,12 @@ package chunk
 
 import (
 	"fmt"
+	"time"
+
 	"github.com/pingcap/check"
 	"github.com/pingcap/parser/mysql"
 	"github.com/pingcap/tidb/types"
 	"github.com/pingcap/tidb/types/json"
-	"time"
 )
 
 func equalColumn(c1, c2 *Column) bool {

From 37d81d769ecaaaeaeeccfdc2d58af4df1cadd577 Mon Sep 17 00:00:00 2001
From: Yuanjia Zhang <zhangyuanjia@pingcap.com>
Date: Mon, 22 Jul 2019 16:00:05 +0800
Subject: [PATCH 13/17] refmt

---
 util/chunk/column_test.go | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/util/chunk/column_test.go b/util/chunk/column_test.go
index 59b709a92ac95..0b0687f3bbb80 100644
--- a/util/chunk/column_test.go
+++ b/util/chunk/column_test.go
@@ -84,7 +84,7 @@ func (s *testChunkSuite) TestI64Column(c *check.C) {
 	i64s := col.Int64s()
 	for i := 0; i < 1024; i++ {
 		c.Assert(i64s[i], check.Equals, int64(i))
-		i64s[i] ++
+		i64s[i]++
 	}
 
 	it := NewIterator4Chunk(chk)

From 669f40106843948fae95ca2645b7965ee5cbbb24 Mon Sep 17 00:00:00 2001
From: Yuanjia Zhang <zhangyuanjia@pingcap.com>
Date: Mon, 22 Jul 2019 16:03:11 +0800
Subject: [PATCH 14/17] make lint happy

---
 util/chunk/column.go | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/util/chunk/column.go b/util/chunk/column.go
index 9e1ec5a8eaae3..c3c417412cba6 100644
--- a/util/chunk/column.go
+++ b/util/chunk/column.go
@@ -49,7 +49,7 @@ func (c *Column) AppendJSON(j json.BinaryJSON) {
 	c.finishAppendVar()
 }
 
-// AppendJSON appends a Set value into this Column.
+// AppendSet appends a Set value into this Column.
 func (c *Column) AppendSet(set types.Set) {
 	c.appendNameValue(set.Name, set.Value)
 }
@@ -70,9 +70,8 @@ func NewColumn(ft *types.FieldType, cap int) *Column {
 	typeSize := getFixedLen(ft)
 	if typeSize == varElemLen {
 		return newVarLenColumn(cap, nil)
-	} else {
-		return newFixedLenColumn(typeSize, cap)
 	}
+	return newFixedLenColumn(typeSize, cap)
 }
 
 func (c *Column) isFixed() bool {
@@ -283,7 +282,7 @@ func (c *Column) GetString(rowID int) string {
 	return string(hack.String(c.data[c.offsets[rowID]:c.offsets[rowID+1]]))
 }
 
-// GetString returns the JSON in the specific row.
+// GetJSON returns the JSON in the specific row.
 func (c *Column) GetJSON(rowID int) json.BinaryJSON {
 	start := c.offsets[rowID]
 	return json.BinaryJSON{TypeCode: c.data[start], Value: c.data[start+1 : c.offsets[rowID+1]]}
@@ -317,7 +316,6 @@ func (c *Column) GetDuration(rowID int, fillFsp int) types.Duration {
 	return types.Duration{Duration: time.Duration(dur), Fsp: fillFsp}
 }
 
-// GetString returns the byte slice in the specific row.
 func (c *Column) getNameValue(rowID int) (string, uint64) {
 	start, end := c.offsets[rowID], c.offsets[rowID+1]
 	if start == end {

From c8b731bb4c99d67e1d4adca0158a4b973037f88b Mon Sep 17 00:00:00 2001
From: Yuanjia Zhang <zhangyuanjia@pingcap.com>
Date: Mon, 22 Jul 2019 16:19:05 +0800
Subject: [PATCH 15/17] refmt

---
 util/chunk/column.go | 37 ++++++++++++-------------------------
 1 file changed, 12 insertions(+), 25 deletions(-)

diff --git a/util/chunk/column.go b/util/chunk/column.go
index c3c417412cba6..33824096c2141 100644
--- a/util/chunk/column.go
+++ b/util/chunk/column.go
@@ -222,58 +222,45 @@ const (
 	sizeMyDecimal = int(unsafe.Sizeof(types.MyDecimal{}))
 )
 
+func (c *Column) castSliceHeader(header *reflect.SliceHeader, typeSize int) {
+	h := (*reflect.SliceHeader)(unsafe.Pointer(&c.data))
+	header.Data = h.Data
+	header.Len = c.length
+	header.Cap = h.Cap / typeSize
+}
+
 // Int64s returns an int64 slice stored in this Column.
 func (c *Column) Int64s() []int64 {
-	h := (*reflect.SliceHeader)(unsafe.Pointer(&c.data))
 	var res []int64
-	s := (*reflect.SliceHeader)(unsafe.Pointer(&res))
-	s.Data = h.Data
-	s.Len = c.length
-	s.Cap = h.Cap / sizeInt64
+	c.castSliceHeader((*reflect.SliceHeader)(unsafe.Pointer(&res)), sizeInt64)
 	return res
 }
 
 // Uint64s returns a uint64 slice stored in this Column.
 func (c *Column) Uint64s() []uint64 {
-	h := (*reflect.SliceHeader)(unsafe.Pointer(&c.data))
 	var res []uint64
-	s := (*reflect.SliceHeader)(unsafe.Pointer(&res))
-	s.Data = h.Data
-	s.Len = c.length
-	s.Cap = h.Cap / sizeUint64
+	c.castSliceHeader((*reflect.SliceHeader)(unsafe.Pointer(&res)), sizeUint64)
 	return res
 }
 
 // Float32s returns a float32 slice stored in this Column.
 func (c *Column) Float32s() []float32 {
-	h := (*reflect.SliceHeader)(unsafe.Pointer(&c.data))
 	var res []float32
-	s := (*reflect.SliceHeader)(unsafe.Pointer(&res))
-	s.Data = h.Data
-	s.Len = c.length
-	s.Cap = h.Cap / sizeFloat32
+	c.castSliceHeader((*reflect.SliceHeader)(unsafe.Pointer(&res)), sizeFloat32)
 	return res
 }
 
 // Float64s returns a float64 slice stored in this Column.
 func (c *Column) Float64s() []float64 {
-	h := (*reflect.SliceHeader)(unsafe.Pointer(&c.data))
 	var res []float64
-	s := (*reflect.SliceHeader)(unsafe.Pointer(&res))
-	s.Data = h.Data
-	s.Len = c.length
-	s.Cap = h.Cap / sizeFloat64
+	c.castSliceHeader((*reflect.SliceHeader)(unsafe.Pointer(&res)), sizeFloat64)
 	return res
 }
 
 // MyDecimals returns a MyDecimal slice stored in this Column.
 func (c *Column) MyDecimals() []types.MyDecimal {
-	h := (*reflect.SliceHeader)(unsafe.Pointer(&c.data))
 	var res []types.MyDecimal
-	s := (*reflect.SliceHeader)(unsafe.Pointer(&res))
-	s.Data = h.Data
-	s.Len = c.length
-	s.Cap = h.Cap / sizeMyDecimal
+	c.castSliceHeader((*reflect.SliceHeader)(unsafe.Pointer(&res)), sizeMyDecimal)
 	return res
 }
 

From 359047d4d8310d4fa3b729d437de0d1d2f7f383d Mon Sep 17 00:00:00 2001
From: Yuanjia Zhang <zhangyuanjia@pingcap.com>
Date: Mon, 22 Jul 2019 16:31:50 +0800
Subject: [PATCH 16/17] address comments

---
 util/chunk/column.go      | 9 ++++-----
 util/chunk/column_test.go | 2 +-
 2 files changed, 5 insertions(+), 6 deletions(-)

diff --git a/util/chunk/column.go b/util/chunk/column.go
index 33824096c2141..d06b1f2e92669 100644
--- a/util/chunk/column.go
+++ b/util/chunk/column.go
@@ -223,10 +223,9 @@ const (
 )
 
 func (c *Column) castSliceHeader(header *reflect.SliceHeader, typeSize int) {
-	h := (*reflect.SliceHeader)(unsafe.Pointer(&c.data))
-	header.Data = h.Data
+	header.Data = uintptr(unsafe.Pointer(&c.data[0]))
 	header.Len = c.length
-	header.Cap = h.Cap / typeSize
+	header.Cap = cap(c.data) / typeSize
 }
 
 // Int64s returns an int64 slice stored in this Column.
@@ -257,8 +256,8 @@ func (c *Column) Float64s() []float64 {
 	return res
 }
 
-// MyDecimals returns a MyDecimal slice stored in this Column.
-func (c *Column) MyDecimals() []types.MyDecimal {
+// Decimals returns a MyDecimal slice stored in this Column.
+func (c *Column) Decimals() []types.MyDecimal {
 	var res []types.MyDecimal
 	c.castSliceHeader((*reflect.SliceHeader)(unsafe.Pointer(&res)), sizeMyDecimal)
 	return res
diff --git a/util/chunk/column_test.go b/util/chunk/column_test.go
index 0b0687f3bbb80..210e270155b84 100644
--- a/util/chunk/column_test.go
+++ b/util/chunk/column_test.go
@@ -148,7 +148,7 @@ func (s *testChunkSuite) TestMyDecimal(c *check.C) {
 		col.AppendMyDecimal(d)
 	}
 
-	ds := col.MyDecimals()
+	ds := col.Decimals()
 	for i := 0; i < 1024; i++ {
 		d := new(types.MyDecimal)
 		if err := d.FromFloat64(float64(i) * 1.1); err != nil {

From 21db4a1f4ec1082e1aabe2ed6859321d10a8f6e5 Mon Sep 17 00:00:00 2001
From: Yuanjia Zhang <zhangyuanjia@pingcap.com>
Date: Mon, 22 Jul 2019 18:40:44 +0800
Subject: [PATCH 17/17] address comments

---
 util/chunk/chunk.go | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/util/chunk/chunk.go b/util/chunk/chunk.go
index 4217d64f1595a..60bc217ac74e5 100644
--- a/util/chunk/chunk.go
+++ b/util/chunk/chunk.go
@@ -551,8 +551,8 @@ func (c *Chunk) AppendDatum(colIdx int, d *types.Datum) {
 }
 
 // Column returns the specific column.
-func (c *Chunk) Column(colID int) *Column {
-	return c.columns[colID]
+func (c *Chunk) Column(colIdx int) *Column {
+	return c.columns[colIdx]
 }
 
 func writeTime(buf []byte, t types.Time) {