tidb func_count_distinct 源码
tidb func_count_distinct 代码
文件路径：/executor/aggfuncs/func_count_distinct.go
// Copyright 2020 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 aggfuncs
import (
"encoding/binary"
"math"
"unsafe"
"github.com/dgryski/go-farm"
"github.com/pingcap/errors"
"github.com/pingcap/tidb/expression"
"github.com/pingcap/tidb/sessionctx"
"github.com/pingcap/tidb/types"
"github.com/pingcap/tidb/util/chunk"
"github.com/pingcap/tidb/util/codec"
"github.com/pingcap/tidb/util/collate"
"github.com/pingcap/tidb/util/hack"
"github.com/pingcap/tidb/util/mathutil"
"github.com/pingcap/tidb/util/set"
"github.com/pingcap/tidb/util/stringutil"
)
const (
// DefPartialResult4CountDistinctIntSize is the size of partialResult4CountDistinctInt
DefPartialResult4CountDistinctIntSize = int64(unsafe.Sizeof(partialResult4CountDistinctInt{}))
// DefPartialResult4CountDistinctRealSize is the size of partialResult4CountDistinctReal
DefPartialResult4CountDistinctRealSize = int64(unsafe.Sizeof(partialResult4CountDistinctReal{}))
// DefPartialResult4CountDistinctDecimalSize is the size of partialResult4CountDistinctDecimal
DefPartialResult4CountDistinctDecimalSize = int64(unsafe.Sizeof(partialResult4CountDistinctDecimal{}))
// DefPartialResult4CountDistinctDurationSize is the size of partialResult4CountDistinctDuration
DefPartialResult4CountDistinctDurationSize = int64(unsafe.Sizeof(partialResult4CountDistinctDuration{}))
// DefPartialResult4CountDistinctStringSize is the size of partialResult4CountDistinctString
DefPartialResult4CountDistinctStringSize = int64(unsafe.Sizeof(partialResult4CountDistinctString{}))
// DefPartialResult4CountWithDistinctSize is the size of partialResult4CountWithDistinct
DefPartialResult4CountWithDistinctSize = int64(unsafe.Sizeof(partialResult4CountWithDistinct{}))
// DefPartialResult4ApproxCountDistinctSize is the size of partialResult4ApproxCountDistinct
DefPartialResult4ApproxCountDistinctSize = int64(unsafe.Sizeof(partialResult4ApproxCountDistinct{}))
)
type partialResult4CountDistinctInt struct {
valSet set.Int64SetWithMemoryUsage
}
type countOriginalWithDistinct4Int struct {
baseCount
}
func (e *countOriginalWithDistinct4Int) AllocPartialResult() (pr PartialResult, memDelta int64) {
valSet, setSize := set.NewInt64SetWithMemoryUsage()
return PartialResult(&partialResult4CountDistinctInt{
valSet: valSet,
}), DefPartialResult4CountDistinctIntSize + setSize
}
func (e *countOriginalWithDistinct4Int) ResetPartialResult(pr PartialResult) {
p := (*partialResult4CountDistinctInt)(pr)
p.valSet, _ = set.NewInt64SetWithMemoryUsage()
}
func (e *countOriginalWithDistinct4Int) AppendFinalResult2Chunk(sctx sessionctx.Context, pr PartialResult, chk *chunk.Chunk) error {
p := (*partialResult4CountDistinctInt)(pr)
chk.AppendInt64(e.ordinal, int64(p.valSet.Count()))
return nil
}
func (e *countOriginalWithDistinct4Int) UpdatePartialResult(sctx sessionctx.Context, rowsInGroup []chunk.Row, pr PartialResult) (memDelta int64, err error) {
p := (*partialResult4CountDistinctInt)(pr)
for _, row := range rowsInGroup {
input, isNull, err := e.args[0].EvalInt(sctx, row)
if err != nil {
return memDelta, err
}
if isNull {
continue
}
if p.valSet.Exist(input) {
continue
}
memDelta += p.valSet.Insert(input)
}
return memDelta, nil
}
type partialResult4CountDistinctReal struct {
valSet set.Float64SetWithMemoryUsage
}
type countOriginalWithDistinct4Real struct {
baseCount
}
func (e *countOriginalWithDistinct4Real) AllocPartialResult() (pr PartialResult, memDelta int64) {
valSet, setSize := set.NewFloat64SetWithMemoryUsage()
return PartialResult(&partialResult4CountDistinctReal{
valSet: valSet,
}), DefPartialResult4CountDistinctRealSize + setSize
}
func (e *countOriginalWithDistinct4Real) ResetPartialResult(pr PartialResult) {
p := (*partialResult4CountDistinctReal)(pr)
p.valSet, _ = set.NewFloat64SetWithMemoryUsage()
}
func (e *countOriginalWithDistinct4Real) AppendFinalResult2Chunk(sctx sessionctx.Context, pr PartialResult, chk *chunk.Chunk) error {
p := (*partialResult4CountDistinctReal)(pr)
chk.AppendInt64(e.ordinal, int64(p.valSet.Count()))
return nil
}
func (e *countOriginalWithDistinct4Real) UpdatePartialResult(sctx sessionctx.Context, rowsInGroup []chunk.Row, pr PartialResult) (memDelta int64, err error) {
p := (*partialResult4CountDistinctReal)(pr)
for _, row := range rowsInGroup {
input, isNull, err := e.args[0].EvalReal(sctx, row)
if err != nil {
return memDelta, err
}
if isNull {
continue
}
if p.valSet.Exist(input) {
continue
}
memDelta += p.valSet.Insert(input)
}
return memDelta, nil
}
type partialResult4CountDistinctDecimal struct {
valSet set.StringSetWithMemoryUsage
}
type countOriginalWithDistinct4Decimal struct {
baseCount
}
func (e *countOriginalWithDistinct4Decimal) AllocPartialResult() (pr PartialResult, memDelta int64) {
valSet, setSize := set.NewStringSetWithMemoryUsage()
return PartialResult(&partialResult4CountDistinctDecimal{
valSet: valSet,
}), DefPartialResult4CountDistinctDecimalSize + setSize
}
func (e *countOriginalWithDistinct4Decimal) ResetPartialResult(pr PartialResult) {
p := (*partialResult4CountDistinctDecimal)(pr)
p.valSet, _ = set.NewStringSetWithMemoryUsage()
}
func (e *countOriginalWithDistinct4Decimal) AppendFinalResult2Chunk(sctx sessionctx.Context, pr PartialResult, chk *chunk.Chunk) error {
p := (*partialResult4CountDistinctDecimal)(pr)
chk.AppendInt64(e.ordinal, int64(p.valSet.Count()))
return nil
}
func (e *countOriginalWithDistinct4Decimal) UpdatePartialResult(sctx sessionctx.Context, rowsInGroup []chunk.Row, pr PartialResult) (memDelta int64, err error) {
p := (*partialResult4CountDistinctDecimal)(pr)
for _, row := range rowsInGroup {
input, isNull, err := e.args[0].EvalDecimal(sctx, row)
if err != nil {
return memDelta, err
}
if isNull {
continue
}
hash, err := input.ToHashKey()
if err != nil {
return memDelta, err
}
decStr := string(hack.String(hash))
if p.valSet.Exist(decStr) {
continue
}
memDelta += p.valSet.Insert(decStr)
memDelta += int64(len(decStr))
}
return memDelta, nil
}
type partialResult4CountDistinctDuration struct {
valSet set.Int64SetWithMemoryUsage
}
type countOriginalWithDistinct4Duration struct {
baseCount
}
func (e *countOriginalWithDistinct4Duration) AllocPartialResult() (pr PartialResult, memDelta int64) {
valSet, setSize := set.NewInt64SetWithMemoryUsage()
return PartialResult(&partialResult4CountDistinctDuration{
valSet: valSet,
}), DefPartialResult4CountDistinctDurationSize + setSize
}
func (e *countOriginalWithDistinct4Duration) ResetPartialResult(pr PartialResult) {
p := (*partialResult4CountDistinctDuration)(pr)
p.valSet, _ = set.NewInt64SetWithMemoryUsage()
}
func (e *countOriginalWithDistinct4Duration) AppendFinalResult2Chunk(sctx sessionctx.Context, pr PartialResult, chk *chunk.Chunk) error {
p := (*partialResult4CountDistinctDuration)(pr)
chk.AppendInt64(e.ordinal, int64(p.valSet.Count()))
return nil
}
func (e *countOriginalWithDistinct4Duration) UpdatePartialResult(sctx sessionctx.Context, rowsInGroup []chunk.Row, pr PartialResult) (memDelta int64, err error) {
p := (*partialResult4CountDistinctDuration)(pr)
for _, row := range rowsInGroup {
input, isNull, err := e.args[0].EvalDuration(sctx, row)
if err != nil {
return memDelta, err
}
if isNull {
continue
}
if p.valSet.Exist(int64(input.Duration)) {
continue
}
memDelta += p.valSet.Insert(int64(input.Duration))
}
return memDelta, nil
}
type partialResult4CountDistinctString struct {
valSet set.StringSetWithMemoryUsage
}
type countOriginalWithDistinct4String struct {
baseCount
}
func (e *countOriginalWithDistinct4String) AllocPartialResult() (pr PartialResult, memDelta int64) {
valSet, setSize := set.NewStringSetWithMemoryUsage()
return PartialResult(&partialResult4CountDistinctString{
valSet: valSet,
}), DefPartialResult4CountDistinctStringSize + setSize
}
func (e *countOriginalWithDistinct4String) ResetPartialResult(pr PartialResult) {
p := (*partialResult4CountDistinctString)(pr)
p.valSet, _ = set.NewStringSetWithMemoryUsage()
}
func (e *countOriginalWithDistinct4String) AppendFinalResult2Chunk(sctx sessionctx.Context, pr PartialResult, chk *chunk.Chunk) error {
p := (*partialResult4CountDistinctString)(pr)
chk.AppendInt64(e.ordinal, int64(p.valSet.Count()))
return nil
}
func (e *countOriginalWithDistinct4String) UpdatePartialResult(sctx sessionctx.Context, rowsInGroup []chunk.Row, pr PartialResult) (memDelta int64, err error) {
p := (*partialResult4CountDistinctString)(pr)
collator := collate.GetCollator(e.args[0].GetType().GetCollate())
for _, row := range rowsInGroup {
input, isNull, err := e.args[0].EvalString(sctx, row)
if err != nil {
return memDelta, err
}
if isNull {
continue
}
input = string(collator.Key(input))
if p.valSet.Exist(input) {
continue
}
input = stringutil.Copy(input)
memDelta += p.valSet.Insert(input)
memDelta += int64(len(input))
}
return memDelta, nil
}
type countOriginalWithDistinct struct {
baseCount
}
type partialResult4CountWithDistinct struct {
valSet set.StringSetWithMemoryUsage
}
func (e *countOriginalWithDistinct) AllocPartialResult() (pr PartialResult, memDelta int64) {
valSet, setSize := set.NewStringSetWithMemoryUsage()
return PartialResult(&partialResult4CountWithDistinct{
valSet: valSet,
}), DefPartialResult4CountWithDistinctSize + setSize
}
func (e *countOriginalWithDistinct) ResetPartialResult(pr PartialResult) {
p := (*partialResult4CountWithDistinct)(pr)
p.valSet, _ = set.NewStringSetWithMemoryUsage()
}
func (e *countOriginalWithDistinct) AppendFinalResult2Chunk(sctx sessionctx.Context, pr PartialResult, chk *chunk.Chunk) error {
p := (*partialResult4CountWithDistinct)(pr)
chk.AppendInt64(e.ordinal, int64(p.valSet.Count()))
return nil
}
func (e *countOriginalWithDistinct) UpdatePartialResult(sctx sessionctx.Context, rowsInGroup []chunk.Row, pr PartialResult) (memDelta int64, err error) {
p := (*partialResult4CountWithDistinct)(pr)
encodedBytes := make([]byte, 0)
collators := make([]collate.Collator, 0, len(e.args))
for _, arg := range e.args {
collators = append(collators, collate.GetCollator(arg.GetType().GetCollate()))
}
// decimal struct is the biggest type we will use.
buf := make([]byte, types.MyDecimalStructSize)
for _, row := range rowsInGroup {
var err error
var hasNull, isNull bool
encodedBytes = encodedBytes[:0]
for i := 0; i < len(e.args) && !hasNull; i++ {
encodedBytes, isNull, err = evalAndEncode(sctx, e.args[i], collators[i], row, buf, encodedBytes)
if err != nil {
return memDelta, err
}
if isNull {
hasNull = true
break
}
}
encodedString := string(encodedBytes)
if hasNull || p.valSet.Exist(encodedString) {
continue
}
memDelta += p.valSet.Insert(encodedString)
memDelta += int64(len(encodedString))
}
return memDelta, nil
}
// evalAndEncode eval one row with an expression and encode value to bytes.
func evalAndEncode(
sctx sessionctx.Context, arg expression.Expression, collator collate.Collator,
row chunk.Row, buf, encodedBytes []byte,
) (_ []byte, isNull bool, err error) {
switch tp := arg.GetType().EvalType(); tp {
case types.ETInt:
var val int64
val, isNull, err = arg.EvalInt(sctx, row)
if err != nil || isNull {
break
}
encodedBytes = appendInt64(encodedBytes, buf, val)
case types.ETReal:
var val float64
val, isNull, err = arg.EvalReal(sctx, row)
if err != nil || isNull {
break
}
encodedBytes = appendFloat64(encodedBytes, buf, val)
case types.ETDecimal:
var val *types.MyDecimal
val, isNull, err = arg.EvalDecimal(sctx, row)
if err != nil || isNull {
break
}
encodedBytes, err = appendDecimal(encodedBytes, val)
case types.ETTimestamp, types.ETDatetime:
var val types.Time
val, isNull, err = arg.EvalTime(sctx, row)
if err != nil || isNull {
break
}
encodedBytes = appendTime(encodedBytes, buf, val)
case types.ETDuration:
var val types.Duration
val, isNull, err = arg.EvalDuration(sctx, row)
if err != nil || isNull {
break
}
encodedBytes = appendDuration(encodedBytes, buf, val)
case types.ETJson:
var val types.BinaryJSON
val, isNull, err = arg.EvalJSON(sctx, row)
if err != nil || isNull {
break
}
encodedBytes = appendJSON(encodedBytes, buf, val)
case types.ETString:
var val string
val, isNull, err = arg.EvalString(sctx, row)
if err != nil || isNull {
break
}
encodedBytes = codec.EncodeCompactBytes(encodedBytes, collator.Key(val))
default:
return nil, false, errors.Errorf("unsupported column type for encode %d", tp)
}
return encodedBytes, isNull, err
}
func appendInt64(encodedBytes, buf []byte, val int64) []byte {
*(*int64)(unsafe.Pointer(&buf[0])) = val
buf = buf[:8]
encodedBytes = append(encodedBytes, buf...)
return encodedBytes
}
func appendFloat64(encodedBytes, buf []byte, val float64) []byte {
*(*float64)(unsafe.Pointer(&buf[0])) = val
buf = buf[:8]
encodedBytes = append(encodedBytes, buf...)
return encodedBytes
}
func appendDecimal(encodedBytes []byte, val *types.MyDecimal) ([]byte, error) {
hash, err := val.ToHashKey()
encodedBytes = append(encodedBytes, hash...)
return encodedBytes, err
}
// WriteTime writes `t` into `buf`.
func WriteTime(buf []byte, t types.Time) {
binary.BigEndian.PutUint16(buf, uint16(t.Year()))
buf[2] = uint8(t.Month())
buf[3] = uint8(t.Day())
buf[4] = uint8(t.Hour())
buf[5] = uint8(t.Minute())
buf[6] = uint8(t.Second())
binary.BigEndian.PutUint32(buf[8:], uint32(t.Microsecond()))
buf[12] = t.Type()
buf[13] = uint8(t.Fsp())
buf[7], buf[14], buf[15] = uint8(0), uint8(0), uint8(0)
}
func appendTime(encodedBytes, buf []byte, val types.Time) []byte {
WriteTime(buf, val)
buf = buf[:16]
encodedBytes = append(encodedBytes, buf...)
return encodedBytes
}
func appendDuration(encodedBytes, buf []byte, val types.Duration) []byte {
*(*types.Duration)(unsafe.Pointer(&buf[0])) = val
buf = buf[:16]
encodedBytes = append(encodedBytes, buf...)
return encodedBytes
}
func appendJSON(encodedBytes, _ []byte, val types.BinaryJSON) []byte {
encodedBytes = append(encodedBytes, val.TypeCode)
encodedBytes = append(encodedBytes, val.Value...)
return encodedBytes
}
func intHash64(x uint64) uint64 {
x ^= x >> 33
x *= 0xff51afd7ed558ccd
x ^= x >> 33
x *= 0xc4ceb9fe1a85ec53
x ^= x >> 33
return x
}
type baseApproxCountDistinct struct {
baseAggFunc
}
const (
// The maximum degree of buffer size before the values are discarded
uniquesHashMaxSizeDegree uint8 = 17
// The maximum number of elements before the values are discarded
uniquesHashMaxSize = uint32(1) << (uniquesHashMaxSizeDegree - 1)
// Initial buffer size degree
uniquesHashSetInitialSizeDegree uint8 = 4
// The number of least significant bits used for thinning. The remaining high-order bits are used to determine the position in the hash table.
uniquesHashBitsForSkip = 32 - uniquesHashMaxSizeDegree
)
type approxCountDistinctHashValue uint32
// partialResult4ApproxCountDistinct use `BJKST` algorithm to compute approximate result of count distinct.
// According to an experimental survey http://www.vldb.org/pvldb/vol11/p499-harmouch.pdf, the error guarantee of BJKST
// was even better than the theoretical lower bounds.
// For the calculation state, it uses a sample of element hash values with a size up to uniquesHashMaxSize. Compared
// with the widely known HyperLogLog algorithm, this algorithm is less effective in terms of accuracy and
// memory consumption (even up to proportionality), but it is adaptive. This means that with fairly high accuracy, it
// consumes less memory during simultaneous computation of cardinality for a large number of data sets whose cardinality
// has power law distribution (i.e. in cases when most of the data sets are small).
// This algorithm is also very accurate for data sets with small cardinality and very efficient on CPU. If number of
// distinct element is more than 2^32, relative error may be high.
type partialResult4ApproxCountDistinct struct {
size uint32 // Number of elements.
sizeDegree uint8 // The size of the table as a power of 2.
skipDegree uint8 // Skip elements not divisible by 2 ^ skipDegree.
hasZero bool // The hash table contains an element with a hash value of 0.
buf []approxCountDistinctHashValue
}
// NewPartialResult4ApproxCountDistinct builds a partial result for agg function ApproxCountDistinct.
func NewPartialResult4ApproxCountDistinct() *partialResult4ApproxCountDistinct {
p := &partialResult4ApproxCountDistinct{}
p.reset()
return p
}
func (p *partialResult4ApproxCountDistinct) InsertHash64(x uint64) {
// no need to rehash, just cast into uint32
p.insertHash(approxCountDistinctHashValue(x))
}
func (p *partialResult4ApproxCountDistinct) MemUsage() int64 {
return int64(len(p.buf)) * DefUint32Size
}
func (p *partialResult4ApproxCountDistinct) alloc(newSizeDegree uint8) {
p.size = 0
p.skipDegree = 0
p.hasZero = false
p.buf = make([]approxCountDistinctHashValue, uint32(1)<<newSizeDegree)
p.sizeDegree = newSizeDegree
}
func (p *partialResult4ApproxCountDistinct) reset() {
p.alloc(uniquesHashSetInitialSizeDegree)
}
func (p *partialResult4ApproxCountDistinct) bufSize() uint32 {
return uint32(1) << p.sizeDegree
}
func (p *partialResult4ApproxCountDistinct) mask() uint32 {
return p.bufSize() - 1
}
func (p *partialResult4ApproxCountDistinct) place(x approxCountDistinctHashValue) uint32 {
return uint32(x>>uniquesHashBitsForSkip) & p.mask()
}
// Increase the size of the buffer 2 times or up to new size degree.
func (p *partialResult4ApproxCountDistinct) resize(newSizeDegree uint8) {
oldSize := p.bufSize()
oldBuf := p.buf
if 0 == newSizeDegree {
newSizeDegree = p.sizeDegree + 1
}
p.buf = make([]approxCountDistinctHashValue, uint32(1)<<newSizeDegree)
p.sizeDegree = newSizeDegree
// Move some items to new locations.
for i := uint32(0); i < oldSize; i++ {
x := oldBuf[i]
if x != 0 {
p.reinsertImpl(x)
}
}
}
func (p *partialResult4ApproxCountDistinct) readAndMerge(rb []byte) error {
rhsSkipDegree := rb[0]
rb = rb[1:]
if rhsSkipDegree > p.skipDegree {
p.skipDegree = rhsSkipDegree
p.rehash()
}
rb, rhsSize, err := codec.DecodeUvarint(rb)
if err != nil {
return err
}
if rhsSize > uint64(uniquesHashMaxSize) {
return errors.New("Cannot read partialResult4ApproxCountDistinct: too large size degree")
}
if p.bufSize() < uint32(rhsSize) {
newSizeDegree := mathutil.Max(uniquesHashSetInitialSizeDegree, uint8(math.Log2(float64(rhsSize-1)))+2)
p.resize(newSizeDegree)
}
for i := uint32(0); i < uint32(rhsSize); i++ {
x := *(*approxCountDistinctHashValue)(unsafe.Pointer(&rb[0]))
rb = rb[4:]
p.insertHash(x)
}
return err
}
// Correct system errors due to collisions during hashing in uint32.
func (p *partialResult4ApproxCountDistinct) fixedSize() uint64 {
if 0 == p.skipDegree {
return uint64(p.size)
}
res := uint64(p.size) * (uint64(1) << p.skipDegree)
// Pseudo-random remainder.
res += intHash64(uint64(p.size)) & ((uint64(1) << p.skipDegree) - 1)
// When different elements randomly scattered across 2^32 buckets, filled buckets with average of `res` obtained.
p32 := uint64(1) << 32
fixedRes := math.Round(float64(p32) * (math.Log(float64(p32)) - math.Log(float64(p32-res))))
return uint64(fixedRes)
}
func (p *partialResult4ApproxCountDistinct) insertHash(hashValue approxCountDistinctHashValue) {
if !p.good(hashValue) {
return
}
p.insertImpl(hashValue)
p.shrinkIfNeed()
}
// The value is divided by 2 ^ skip_degree
func (p *partialResult4ApproxCountDistinct) good(hash approxCountDistinctHashValue) bool {
return hash == ((hash >> p.skipDegree) << p.skipDegree)
}
// Insert a value
func (p *partialResult4ApproxCountDistinct) insertImpl(x approxCountDistinctHashValue) {
if x == 0 {
if !p.hasZero {
p.size += 1
}
p.hasZero = true
return
}
placeValue := p.place(x)
for p.buf[placeValue] != 0 && p.buf[placeValue] != x {
placeValue++
placeValue &= p.mask()
}
if p.buf[placeValue] == x {
return
}
p.buf[placeValue] = x
p.size++
}
// If the hash table is full enough, then do resize.
// If there are too many items, then throw half the pieces until they are small enough.
func (p *partialResult4ApproxCountDistinct) shrinkIfNeed() {
if p.size > p.maxFill() {
if p.size > uniquesHashMaxSize {
for p.size > uniquesHashMaxSize {
p.skipDegree++
p.rehash()
}
} else {
p.resize(0)
}
}
}
func (p *partialResult4ApproxCountDistinct) maxFill() uint32 {
return uint32(1) << (p.sizeDegree - 1)
}
// Delete all values whose hashes do not divide by 2 ^ skip_degree
func (p *partialResult4ApproxCountDistinct) rehash() {
for i := uint32(0); i < p.bufSize(); i++ {
if p.buf[i] != 0 && !p.good(p.buf[i]) {
p.buf[i] = 0
p.size--
}
}
for i := uint32(0); i < p.bufSize(); i++ {
if p.buf[i] != 0 && i != p.place(p.buf[i]) {
x := p.buf[i]
p.buf[i] = 0
p.reinsertImpl(x)
}
}
}
// Insert a value into the new buffer that was in the old buffer.
// Used when increasing the size of the buffer, as well as when reading from a file.
func (p *partialResult4ApproxCountDistinct) reinsertImpl(x approxCountDistinctHashValue) {
placeValue := p.place(x)
for p.buf[placeValue] != 0 {
placeValue++
placeValue &= p.mask()
}
p.buf[placeValue] = x
}
func (p *partialResult4ApproxCountDistinct) merge(tar *partialResult4ApproxCountDistinct) {
if tar.skipDegree > p.skipDegree {
p.skipDegree = tar.skipDegree
p.rehash()
}
if !p.hasZero && tar.hasZero {
p.hasZero = true
p.size++
p.shrinkIfNeed()
}
for i := uint32(0); i < tar.bufSize(); i++ {
if tar.buf[i] != 0 && p.good(tar.buf[i]) {
p.insertImpl(tar.buf[i])
p.shrinkIfNeed()
}
}
}
func (p *partialResult4ApproxCountDistinct) Serialize() []byte {
var buf [4]byte
res := make([]byte, 0, 1+binary.MaxVarintLen64+p.size*4)
res = append(res, p.skipDegree)
res = codec.EncodeUvarint(res, uint64(p.size))
if p.hasZero {
binary.LittleEndian.PutUint32(buf[:], 0)
res = append(res, buf[:]...)
}
for i := uint32(0); i < p.bufSize(); i++ {
if p.buf[i] != 0 {
binary.LittleEndian.PutUint32(buf[:], uint32(p.buf[i]))
res = append(res, buf[:]...)
}
}
return res
}
func (e *baseApproxCountDistinct) AppendFinalResult2Chunk(sctx sessionctx.Context, pr PartialResult, chk *chunk.Chunk) error {
p := (*partialResult4ApproxCountDistinct)(pr)
chk.AppendInt64(e.ordinal, int64(p.fixedSize()))
return nil
}
func (e *baseApproxCountDistinct) AllocPartialResult() (pr PartialResult, memDelta int64) {
return (PartialResult)(NewPartialResult4ApproxCountDistinct()), DefPartialResult4ApproxCountDistinctSize
}
func (e *baseApproxCountDistinct) ResetPartialResult(pr PartialResult) {
p := (*partialResult4ApproxCountDistinct)(pr)
p.reset()
}
func (e *baseApproxCountDistinct) MergePartialResult(sctx sessionctx.Context, src, dst PartialResult) (memDelta int64, err error) {
p1, p2 := (*partialResult4ApproxCountDistinct)(src), (*partialResult4ApproxCountDistinct)(dst)
p2.merge(p1)
return 0, nil
}
type approxCountDistinctOriginal struct {
baseApproxCountDistinct
}
func (e *approxCountDistinctOriginal) UpdatePartialResult(sctx sessionctx.Context, rowsInGroup []chunk.Row, pr PartialResult) (memDelta int64, err error) {
p := (*partialResult4ApproxCountDistinct)(pr)
encodedBytes := make([]byte, 0)
// decimal struct is the biggest type we will use.
buf := make([]byte, types.MyDecimalStructSize)
collators := make([]collate.Collator, 0, len(e.args))
for _, arg := range e.args {
collators = append(collators, collate.GetCollator(arg.GetType().GetCollate()))
}
for _, row := range rowsInGroup {
var err error
var hasNull, isNull bool
encodedBytes = encodedBytes[:0]
for i := 0; i < len(e.args) && !hasNull; i++ {
encodedBytes, isNull, err = evalAndEncode(sctx, e.args[i], collators[i], row, buf, encodedBytes)
if err != nil {
return memDelta, err
}
if isNull {
hasNull = true
break
}
}
if hasNull {
continue
}
oldMemUsage := p.MemUsage()
x := farm.Hash64(encodedBytes)
p.InsertHash64(x)
newMemUsage := p.MemUsage()
memDelta += newMemUsage - oldMemUsage
}
return memDelta, nil
}
type approxCountDistinctPartial1 struct {
approxCountDistinctOriginal
}
func (e *approxCountDistinctPartial1) AppendFinalResult2Chunk(sctx sessionctx.Context, pr PartialResult, chk *chunk.Chunk) error {
p := (*partialResult4ApproxCountDistinct)(pr)
chk.AppendBytes(e.ordinal, p.Serialize())
return nil
}
type approxCountDistinctPartial2 struct {
approxCountDistinctPartial1
}
func (e *approxCountDistinctPartial2) UpdatePartialResult(sctx sessionctx.Context, rowsInGroup []chunk.Row, pr PartialResult) (memDelta int64, err error) {
p := (*partialResult4ApproxCountDistinct)(pr)
for _, row := range rowsInGroup {
input, isNull, err := e.args[0].EvalString(sctx, row)
if err != nil {
return memDelta, err
}
if isNull {
continue
}
oldMemUsage := p.MemUsage()
err = p.readAndMerge(hack.Slice(input))
if err != nil {
return memDelta, err
}
newMemUsage := p.MemUsage()
memDelta += newMemUsage - oldMemUsage
}
return memDelta, nil
}
type approxCountDistinctFinal struct {
approxCountDistinctPartial2
}
func (e *approxCountDistinctFinal) AppendFinalResult2Chunk(sctx sessionctx.Context, pr PartialResult, chk *chunk.Chunk) error {
return e.baseApproxCountDistinct.AppendFinalResult2Chunk(sctx, pr, chk)
}
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