tidb column 源码
tidb column 代码
文件路径：/util/chunk/column.go
// Copyright 2018 PingCAP, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package chunk
import (
"fmt"
"math/bits"
"reflect"
"time"
"unsafe"
"github.com/pingcap/tidb/types"
"github.com/pingcap/tidb/util/hack"
)
// AppendDuration appends a duration value into this Column.
// Fsp is ignored.
func (c *Column) AppendDuration(dur types.Duration) {
c.AppendInt64(int64(dur.Duration))
}
// AppendMyDecimal appends a MyDecimal value into this Column.
func (c *Column) AppendMyDecimal(dec *types.MyDecimal) {
*(*types.MyDecimal)(unsafe.Pointer(&c.elemBuf[0])) = *dec
c.finishAppendFixed()
}
func (c *Column) appendNameValue(name string, val uint64) {
var buf [8]byte
copy(buf[:], (*[8]byte)(unsafe.Pointer(&val))[:])
c.data = append(c.data, buf[:]...)
c.data = append(c.data, name...)
c.finishAppendVar()
}
// AppendJSON appends a BinaryJSON value into this Column.
func (c *Column) AppendJSON(j types.BinaryJSON) {
c.data = append(c.data, j.TypeCode)
c.data = append(c.data, j.Value...)
c.finishAppendVar()
}
// AppendSet 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/format/Columnar.html#format-columnar
type Column struct {
length int
nullBitmap []byte // bit 0 is null, 1 is not null
offsets []int64 // used for varLen column. Row i starts from data[offsets[i]]
data []byte
elemBuf []byte
avoidReusing bool // avoid reusing the Column by allocator
}
// ColumnAllocator defines an allocator for Column.
type ColumnAllocator interface {
NewColumn(ft *types.FieldType, count int) *Column
}
// DefaultColumnAllocator is the default implementation of ColumnAllocator.
type DefaultColumnAllocator struct{}
// NewColumn implements the ColumnAllocator interface.
func (DefaultColumnAllocator) NewColumn(ft *types.FieldType, capacity int) *Column {
return newColumn(getFixedLen(ft), capacity)
}
// NewColumn creates a new column with the specific type and capacity.
func NewColumn(ft *types.FieldType, capacity int) *Column {
return newColumn(getFixedLen(ft), capacity)
}
func newColumn(ts, capacity int) *Column {
var col *Column
if ts == varElemLen {
col = newVarLenColumn(capacity)
} else {
col = newFixedLenColumn(ts, capacity)
}
return col
}
// newFixedLenColumn creates a fixed length Column with elemLen and initial data capacity.
func newFixedLenColumn(elemLen, capacity int) *Column {
return &Column{
elemBuf: make([]byte, elemLen),
data: make([]byte, 0, capacity*elemLen),
nullBitmap: make([]byte, 0, (capacity+7)>>3),
}
}
// newVarLenColumn creates a variable length Column with initial data capacity.
func newVarLenColumn(capacity int) *Column {
estimatedElemLen := 8
// For varLenColumn (e.g. varchar), the accurate length of an element is unknown.
// Therefore, in the first executor.Next we use an experience value -- 8 (so it may make runtime.growslice)
return &Column{
offsets: make([]int64, 1, capacity+1),
data: make([]byte, 0, capacity*estimatedElemLen),
nullBitmap: make([]byte, 0, (capacity+7)>>3),
}
}
func (c *Column) typeSize() int {
if len(c.elemBuf) > 0 {
return len(c.elemBuf)
}
return varElemLen
}
func (c *Column) isFixed() bool {
return c.elemBuf != nil
}
// Reset resets this Column according to the EvalType.
// Different from reset, Reset will reset the elemBuf.
func (c *Column) Reset(eType types.EvalType) {
switch eType {
case types.ETInt:
c.ResizeInt64(0, false)
case types.ETReal:
c.ResizeFloat64(0, false)
case types.ETDecimal:
c.ResizeDecimal(0, false)
case types.ETString:
c.ReserveString(0)
case types.ETDatetime, types.ETTimestamp:
c.ResizeTime(0, false)
case types.ETDuration:
c.ResizeGoDuration(0, false)
case types.ETJson:
c.ReserveJSON(0)
default:
panic(fmt.Sprintf("invalid EvalType %v", eType))
}
}
// reset resets the underlying data of this Column but doesn't modify its data type.
func (c *Column) reset() {
c.length = 0
c.nullBitmap = c.nullBitmap[:0]
if len(c.offsets) > 0 {
// The first offset is always 0, it makes slicing the data easier, we need to keep it.
c.offsets = c.offsets[:1]
}
c.data = c.data[:0]
}
// 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
}
// CopyConstruct copies this Column to dst.
// If dst is nil, it creates a new Column and returns it.
func (c *Column) CopyConstruct(dst *Column) *Column {
if dst != nil {
dst.length = c.length
dst.nullBitmap = append(dst.nullBitmap[:0], c.nullBitmap...)
dst.offsets = append(dst.offsets[:0], c.offsets...)
dst.data = append(dst.data[:0], c.data...)
dst.elemBuf = append(dst.elemBuf[:0], c.elemBuf...)
return dst
}
newCol := &Column{length: c.length}
newCol.nullBitmap = append(newCol.nullBitmap, c.nullBitmap...)
newCol.offsets = append(newCol.offsets, c.offsets...)
newCol.data = append(newCol.data, c.data...)
newCol.elemBuf = append(newCol.elemBuf, c.elemBuf...)
return newCol
}
func (c *Column) appendNullBitmap(notNull bool) {
idx := c.length >> 3
if idx >= len(c.nullBitmap) {
c.nullBitmap = append(c.nullBitmap, 0)
}
if notNull {
pos := uint(c.length) & 7
c.nullBitmap[idx] |= byte(1 << pos)
}
}
// appendMultiSameNullBitmap appends multiple same bit value to `nullBitMap`.
// notNull means not null.
// num means the number of bits that should be appended.
func (c *Column) appendMultiSameNullBitmap(notNull bool, num int) {
numNewBytes := ((c.length + num + 7) >> 3) - len(c.nullBitmap)
b := byte(0)
if notNull {
b = 0xff
}
for i := 0; i < numNewBytes; i++ {
c.nullBitmap = append(c.nullBitmap, b)
}
if !notNull {
return
}
// 1. Set all the remaining bits in the last slot of old c.numBitMap to 1.
numRemainingBits := uint(c.length % 8)
bitMask := byte(^((1 << numRemainingBits) - 1))
c.nullBitmap[c.length/8] |= bitMask
// 2. Set all the redundant bits in the last slot of new c.numBitMap to 0.
numRedundantBits := uint(len(c.nullBitmap)*8 - c.length - num)
bitMask = byte(1<<(8-numRedundantBits)) - 1
c.nullBitmap[len(c.nullBitmap)-1] &= bitMask
}
// AppendNull appends a null value into this Column.
func (c *Column) AppendNull() {
c.appendNullBitmap(false)
if c.isFixed() {
c.data = append(c.data, c.elemBuf...)
} else {
c.offsets = append(c.offsets, c.offsets[c.length])
}
c.length++
}
func (c *Column) finishAppendFixed() {
c.data = append(c.data, c.elemBuf...)
c.appendNullBitmap(true)
c.length++
}
// AppendInt64 appends an int64 value into this Column.
func (c *Column) AppendInt64(i int64) {
*(*int64)(unsafe.Pointer(&c.elemBuf[0])) = i
c.finishAppendFixed()
}
// AppendUint64 appends a uint64 value into this Column.
func (c *Column) AppendUint64(u uint64) {
*(*uint64)(unsafe.Pointer(&c.elemBuf[0])) = u
c.finishAppendFixed()
}
// AppendFloat32 appends a float32 value into this Column.
func (c *Column) AppendFloat32(f float32) {
*(*float32)(unsafe.Pointer(&c.elemBuf[0])) = f
c.finishAppendFixed()
}
// AppendFloat64 appends a float64 value into this Column.
func (c *Column) AppendFloat64(f float64) {
*(*float64)(unsafe.Pointer(&c.elemBuf[0])) = f
c.finishAppendFixed()
}
func (c *Column) finishAppendVar() {
c.appendNullBitmap(true)
c.offsets = append(c.offsets, int64(len(c.data)))
c.length++
}
// AppendString appends a string value into this Column.
func (c *Column) AppendString(str string) {
c.data = append(c.data, str...)
c.finishAppendVar()
}
// AppendBytes appends a byte slice into this Column.
func (c *Column) AppendBytes(b []byte) {
c.data = append(c.data, b...)
c.finishAppendVar()
}
// AppendTime appends a time value into this Column.
func (c *Column) AppendTime(t types.Time) {
*(*types.Time)(unsafe.Pointer(&c.elemBuf[0])) = t
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)))
sizeFloat32 = int(unsafe.Sizeof(float32(0)))
sizeFloat64 = int(unsafe.Sizeof(float64(0)))
sizeMyDecimal = int(unsafe.Sizeof(types.MyDecimal{}))
sizeGoDuration = int(unsafe.Sizeof(time.Duration(0)))
sizeTime = int(unsafe.Sizeof(types.ZeroTime))
)
var (
emptyBuf = make([]byte, 4*1024)
)
// resize resizes the column so that it contains n elements, only valid for fixed-length types.
func (c *Column) resize(n, typeSize int, isNull bool) {
sizeData := n * typeSize
if cap(c.data) >= sizeData {
(*reflect.SliceHeader)(unsafe.Pointer(&c.data)).Len = sizeData
} else {
c.data = make([]byte, sizeData)
}
if !isNull {
for j := 0; j < sizeData; j += len(emptyBuf) {
copy(c.data[j:], emptyBuf)
}
}
newNulls := false
sizeNulls := (n + 7) >> 3
if cap(c.nullBitmap) >= sizeNulls {
(*reflect.SliceHeader)(unsafe.Pointer(&c.nullBitmap)).Len = sizeNulls
} else {
c.nullBitmap = make([]byte, sizeNulls)
newNulls = true
}
if !isNull || !newNulls {
var nullVal, lastByte byte
if !isNull {
nullVal = 0xFF
}
// Fill the null bitmap
for i := range c.nullBitmap {
c.nullBitmap[i] = nullVal
}
// Revise the last byte if necessary, when it's not divided by 8.
if x := (n % 8); x != 0 {
if !isNull {
lastByte = byte((1 << x) - 1)
if len(c.nullBitmap) > 0 {
c.nullBitmap[len(c.nullBitmap)-1] = lastByte
}
}
}
}
if cap(c.elemBuf) >= typeSize {
(*reflect.SliceHeader)(unsafe.Pointer(&c.elemBuf)).Len = typeSize
} else {
c.elemBuf = make([]byte, typeSize)
}
c.length = n
}
// reserve makes the column capacity be at least enough to contain n elements.
// this method is only valid for var-length types and estElemSize is the estimated size of this type.
func (c *Column) reserve(n, estElemSize int) {
sizeData := n * estElemSize
if cap(c.data) >= sizeData {
c.data = c.data[:0]
} else {
c.data = make([]byte, 0, sizeData)
}
sizeNulls := (n + 7) >> 3
if cap(c.nullBitmap) >= sizeNulls {
c.nullBitmap = c.nullBitmap[:0]
} else {
c.nullBitmap = make([]byte, 0, sizeNulls)
}
sizeOffs := n + 1
if cap(c.offsets) >= sizeOffs {
c.offsets = c.offsets[:1]
} else {
c.offsets = make([]int64, 1, sizeOffs)
}
c.elemBuf = nil
c.length = 0
}
// SetNull sets the rowIdx to null.
func (c *Column) SetNull(rowIdx int, isNull bool) {
if isNull {
c.nullBitmap[rowIdx>>3] &= ^(1 << uint(rowIdx&7))
} else {
c.nullBitmap[rowIdx>>3] |= 1 << uint(rowIdx&7)
}
}
// SetNulls sets rows in [begin, end) to null.
func (c *Column) SetNulls(begin, end int, isNull bool) {
i := ((begin + 7) >> 3) << 3
for ; begin < i && begin < end; begin++ {
c.SetNull(begin, isNull)
}
var v uint8
if !isNull {
v = (1 << 8) - 1
}
for ; begin+8 <= end; begin += 8 {
c.nullBitmap[begin>>3] = v
}
for ; begin < end; begin++ {
c.SetNull(begin, isNull)
}
}
// nullCount returns the number of nulls in this Column.
func (c *Column) nullCount() int {
var cnt, i int
for ; i+8 <= c.length; i += 8 {
// 0 is null and 1 is not null
cnt += 8 - bits.OnesCount8(c.nullBitmap[i>>3])
}
for ; i < c.length; i++ {
if c.IsNull(i) {
cnt++
}
}
return cnt
}
// ResizeInt64 resizes the column so that it contains n int64 elements.
func (c *Column) ResizeInt64(n int, isNull bool) {
c.resize(n, sizeInt64, isNull)
}
// ResizeUint64 resizes the column so that it contains n uint64 elements.
func (c *Column) ResizeUint64(n int, isNull bool) {
c.resize(n, sizeUint64, isNull)
}
// ResizeFloat32 resizes the column so that it contains n float32 elements.
func (c *Column) ResizeFloat32(n int, isNull bool) {
c.resize(n, sizeFloat32, isNull)
}
// ResizeFloat64 resizes the column so that it contains n float64 elements.
func (c *Column) ResizeFloat64(n int, isNull bool) {
c.resize(n, sizeFloat64, isNull)
}
// ResizeDecimal resizes the column so that it contains n decimal elements.
func (c *Column) ResizeDecimal(n int, isNull bool) {
c.resize(n, sizeMyDecimal, isNull)
}
// ResizeGoDuration resizes the column so that it contains n duration elements.
func (c *Column) ResizeGoDuration(n int, isNull bool) {
c.resize(n, sizeGoDuration, isNull)
}
// ResizeTime resizes the column so that it contains n Time elements.
func (c *Column) ResizeTime(n int, isNull bool) {
c.resize(n, sizeTime, isNull)
}
// ReserveString changes the column capacity to store n string elements and set the length to zero.
func (c *Column) ReserveString(n int) {
c.reserve(n, 8)
}
// ReserveBytes changes the column capacity to store n bytes elements and set the length to zero.
func (c *Column) ReserveBytes(n int) {
c.reserve(n, 8)
}
// ReserveJSON changes the column capacity to store n JSON elements and set the length to zero.
func (c *Column) ReserveJSON(n int) {
c.reserve(n, 8)
}
// ReserveSet changes the column capacity to store n set elements and set the length to zero.
func (c *Column) ReserveSet(n int) {
c.reserve(n, 8)
}
// ReserveEnum changes the column capacity to store n enum elements and set the length to zero.
func (c *Column) ReserveEnum(n int) {
c.reserve(n, 8)
}
func (c *Column) castSliceHeader(header *reflect.SliceHeader, typeSize int) {
header.Data = (*reflect.SliceHeader)(unsafe.Pointer(&c.data)).Data
header.Len = c.length
header.Cap = cap(c.data) / typeSize
}
// Int64s returns an int64 slice stored in this Column.
func (c *Column) Int64s() []int64 {
var res []int64
c.castSliceHeader((*reflect.SliceHeader)(unsafe.Pointer(&res)), sizeInt64)
return res
}
// Uint64s returns a uint64 slice stored in this Column.
func (c *Column) Uint64s() []uint64 {
var res []uint64
c.castSliceHeader((*reflect.SliceHeader)(unsafe.Pointer(&res)), sizeUint64)
return res
}
// Float32s returns a float32 slice stored in this Column.
func (c *Column) Float32s() []float32 {
var res []float32
c.castSliceHeader((*reflect.SliceHeader)(unsafe.Pointer(&res)), sizeFloat32)
return res
}
// Float64s returns a float64 slice stored in this Column.
func (c *Column) Float64s() []float64 {
var res []float64
c.castSliceHeader((*reflect.SliceHeader)(unsafe.Pointer(&res)), sizeFloat64)
return res
}
// GoDurations returns a Golang time.Duration slice stored in this Column.
// Different from the Row.GetDuration method, the argument Fsp is ignored, so the user should handle it outside.
func (c *Column) GoDurations() []time.Duration {
var res []time.Duration
c.castSliceHeader((*reflect.SliceHeader)(unsafe.Pointer(&res)), sizeGoDuration)
return res
}
// 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
}
// Times returns a Time slice stored in this Column.
func (c *Column) Times() []types.Time {
var res []types.Time
c.castSliceHeader((*reflect.SliceHeader)(unsafe.Pointer(&res)), sizeTime)
return res
}
// GetInt64 returns the int64 in the specific row.
func (c *Column) GetInt64(rowID int) int64 {
return *(*int64)(unsafe.Pointer(&c.data[rowID*8]))
}
// GetUint64 returns the uint64 in the specific row.
func (c *Column) GetUint64(rowID int) uint64 {
return *(*uint64)(unsafe.Pointer(&c.data[rowID*8]))
}
// GetFloat32 returns the float32 in the specific row.
func (c *Column) GetFloat32(rowID int) float32 {
return *(*float32)(unsafe.Pointer(&c.data[rowID*4]))
}
// GetFloat64 returns the float64 in the specific row.
func (c *Column) GetFloat64(rowID int) float64 {
return *(*float64)(unsafe.Pointer(&c.data[rowID*8]))
}
// GetDecimal returns the decimal in the specific row.
func (c *Column) GetDecimal(rowID int) *types.MyDecimal {
return (*types.MyDecimal)(unsafe.Pointer(&c.data[rowID*types.MyDecimalStructSize]))
}
// 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]]))
}
// GetJSON returns the JSON in the specific row.
func (c *Column) GetJSON(rowID int) types.BinaryJSON {
start := c.offsets[rowID]
return types.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}
}
// GetTime returns the Time in the specific row.
func (c *Column) GetTime(rowID int) types.Time {
return *(*types.Time)(unsafe.Pointer(&c.data[rowID*sizeTime]))
}
// 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}
}
func (c *Column) getNameValue(rowID int) (string, uint64) {
start, end := c.offsets[rowID], c.offsets[rowID+1]
if start == end {
return "", 0
}
var val uint64
copy((*[8]byte)(unsafe.Pointer(&val))[:], c.data[start:])
return string(hack.String(c.data[start+8 : end])), val
}
// GetRaw returns the underlying raw bytes in the specific row.
func (c *Column) GetRaw(rowID int) []byte {
var data []byte
if c.isFixed() {
elemLen := len(c.elemBuf)
data = c.data[rowID*elemLen : rowID*elemLen+elemLen]
} else {
data = c.data[c.offsets[rowID]:c.offsets[rowID+1]]
}
return data
}
// SetRaw sets the raw bytes for the rowIdx-th element.
// NOTE: Two conditions must be satisfied before calling this function:
// 1. The column should be stored with variable-length elements.
// 2. The length of the new element should be exactly the same as the old one.
func (c *Column) SetRaw(rowID int, bs []byte) {
copy(c.data[c.offsets[rowID]:c.offsets[rowID+1]], bs)
}
// reconstruct reconstructs this Column by removing all filtered rows in it according to sel.
func (c *Column) reconstruct(sel []int) {
if sel == nil {
return
}
if c.isFixed() {
elemLen := len(c.elemBuf)
for dst, src := range sel {
idx := dst >> 3
pos := uint16(dst & 7)
if c.IsNull(src) {
c.nullBitmap[idx] &= ^byte(1 << pos)
} else {
copy(c.data[dst*elemLen:dst*elemLen+elemLen], c.data[src*elemLen:src*elemLen+elemLen])
c.nullBitmap[idx] |= byte(1 << pos)
}
}
c.data = c.data[:len(sel)*elemLen]
} else {
tail := 0
for dst, src := range sel {
idx := dst >> 3
pos := uint(dst & 7)
if c.IsNull(src) {
c.nullBitmap[idx] &= ^byte(1 << pos)
c.offsets[dst+1] = int64(tail)
} else {
start, end := c.offsets[src], c.offsets[src+1]
copy(c.data[tail:], c.data[start:end])
tail += int(end - start)
c.offsets[dst+1] = int64(tail)
c.nullBitmap[idx] |= byte(1 << pos)
}
}
c.data = c.data[:tail]
c.offsets = c.offsets[:len(sel)+1]
}
c.length = len(sel)
// clean nullBitmap
c.nullBitmap = c.nullBitmap[:(len(sel)+7)>>3]
idx := len(sel) >> 3
if idx < len(c.nullBitmap) {
pos := uint16(len(sel) & 7)
c.nullBitmap[idx] &= byte((1 << pos) - 1)
}
}
// CopyReconstruct copies this Column to dst and removes unselected rows.
// If dst is nil, it creates a new Column and returns it.
func (c *Column) CopyReconstruct(sel []int, dst *Column) *Column {
if sel == nil {
return c.CopyConstruct(dst)
}
selLength := len(sel)
if selLength == c.length {
// The variable 'ascend' is used to check if the sel array is in ascending order
ascend := true
for i := 1; i < selLength; i++ {
if sel[i] < sel[i-1] {
ascend = false
break
}
}
if ascend {
return c.CopyConstruct(dst)
}
}
if dst == nil {
dst = newColumn(c.typeSize(), len(sel))
} else {
dst.reset()
}
if c.isFixed() {
elemLen := len(c.elemBuf)
dst.elemBuf = make([]byte, elemLen)
for _, i := range sel {
dst.appendNullBitmap(!c.IsNull(i))
dst.data = append(dst.data, c.data[i*elemLen:i*elemLen+elemLen]...)
dst.length++
}
} else {
dst.elemBuf = nil
if len(dst.offsets) == 0 {
dst.offsets = append(dst.offsets, 0)
}
for _, i := range sel {
dst.appendNullBitmap(!c.IsNull(i))
start, end := c.offsets[i], c.offsets[i+1]
dst.data = append(dst.data, c.data[start:end]...)
dst.offsets = append(dst.offsets, int64(len(dst.data)))
dst.length++
}
}
return dst
}
// MergeNulls merges these columns' null bitmaps.
// For a row, if any column of it is null, the result is null.
// It works like: if col1.IsNull || col2.IsNull || col3.IsNull.
// The caller should ensure that all these columns have the same
// length, and data stored in the result column is fixed-length type.
func (c *Column) MergeNulls(cols ...*Column) {
if !c.isFixed() {
panic("result column should be fixed-length type")
}
for _, col := range cols {
if c.length != col.length {
panic(fmt.Sprintf("should ensure all columns have the same length, expect %v, but got %v", c.length, col.length))
}
}
for _, col := range cols {
for i := range c.nullBitmap {
// bit 0 is null, 1 is not null, so do AND operations here.
c.nullBitmap[i] &= col.nullBitmap[i]
}
}
}
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