419 lines
12 KiB
Go
419 lines
12 KiB
Go
// Copyright 2019 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,
|
|
// See the License for the specific language governing permissions and
|
|
// limitations under the License.
|
|
|
|
package executor
|
|
|
|
import (
|
|
"context"
|
|
|
|
"github.com/cznic/mathutil"
|
|
"github.com/pingcap/errors"
|
|
"github.com/pingcap/parser/ast"
|
|
"github.com/pingcap/tidb/executor/aggfuncs"
|
|
"github.com/pingcap/tidb/expression"
|
|
"github.com/pingcap/tidb/planner/core"
|
|
"github.com/pingcap/tidb/sessionctx"
|
|
"github.com/pingcap/tidb/util/chunk"
|
|
)
|
|
|
|
// WindowExec is the executor for window functions.
|
|
type WindowExec struct {
|
|
baseExecutor
|
|
|
|
groupChecker *groupChecker
|
|
// inputIter is the iterator of child chunks
|
|
inputIter *chunk.Iterator4Chunk
|
|
// executed indicates the child executor is drained or something unexpected happened.
|
|
executed bool
|
|
// resultChunks stores the chunks to return
|
|
resultChunks []*chunk.Chunk
|
|
// remainingRowsInChunk indicates how many rows the resultChunks[i] is not prepared.
|
|
remainingRowsInChunk []int
|
|
|
|
numWindowFuncs int
|
|
processor windowProcessor
|
|
}
|
|
|
|
// Close implements the Executor Close interface.
|
|
func (e *WindowExec) Close() error {
|
|
return errors.Trace(e.baseExecutor.Close())
|
|
}
|
|
|
|
// Next implements the Executor Next interface.
|
|
func (e *WindowExec) Next(ctx context.Context, chk *chunk.Chunk) error {
|
|
chk.Reset()
|
|
for !e.executed && !e.preparedChunkAvailable() {
|
|
err := e.consumeOneGroup(ctx)
|
|
if err != nil {
|
|
e.executed = true
|
|
return err
|
|
}
|
|
}
|
|
if len(e.resultChunks) > 0 {
|
|
chk.SwapColumns(e.resultChunks[0])
|
|
e.resultChunks[0] = nil // GC it. TODO: Reuse it.
|
|
e.resultChunks = e.resultChunks[1:]
|
|
e.remainingRowsInChunk = e.remainingRowsInChunk[1:]
|
|
}
|
|
return nil
|
|
}
|
|
|
|
func (e *WindowExec) preparedChunkAvailable() bool {
|
|
return len(e.resultChunks) > 0 && e.remainingRowsInChunk[0] == 0
|
|
}
|
|
|
|
func (e *WindowExec) consumeOneGroup(ctx context.Context) error {
|
|
var groupRows []chunk.Row
|
|
for {
|
|
eof, err := e.fetchChildIfNecessary(ctx)
|
|
if err != nil {
|
|
return errors.Trace(err)
|
|
}
|
|
if eof {
|
|
e.executed = true
|
|
return e.consumeGroupRows(groupRows)
|
|
}
|
|
for inputRow := e.inputIter.Current(); inputRow != e.inputIter.End(); inputRow = e.inputIter.Next() {
|
|
meetNewGroup, err := e.groupChecker.meetNewGroup(inputRow)
|
|
if err != nil {
|
|
return errors.Trace(err)
|
|
}
|
|
if meetNewGroup {
|
|
return e.consumeGroupRows(groupRows)
|
|
}
|
|
groupRows = append(groupRows, inputRow)
|
|
}
|
|
}
|
|
}
|
|
|
|
func (e *WindowExec) consumeGroupRows(groupRows []chunk.Row) (err error) {
|
|
remainingRowsInGroup := len(groupRows)
|
|
if remainingRowsInGroup == 0 {
|
|
return nil
|
|
}
|
|
for i := 0; i < len(e.resultChunks); i++ {
|
|
remained := mathutil.Min(e.remainingRowsInChunk[i], remainingRowsInGroup)
|
|
e.remainingRowsInChunk[i] -= remained
|
|
remainingRowsInGroup -= remained
|
|
|
|
// TODO: Combine these three methods.
|
|
// The old implementation needs the processor has these three methods
|
|
// but now it does not have to.
|
|
groupRows, err = e.processor.consumeGroupRows(e.ctx, groupRows)
|
|
if err != nil {
|
|
return errors.Trace(err)
|
|
}
|
|
_, err = e.processor.appendResult2Chunk(e.ctx, groupRows, e.resultChunks[i], remained)
|
|
if err != nil {
|
|
return errors.Trace(err)
|
|
}
|
|
if remainingRowsInGroup == 0 {
|
|
e.processor.resetPartialResult()
|
|
break
|
|
}
|
|
}
|
|
return nil
|
|
}
|
|
|
|
func (e *WindowExec) fetchChildIfNecessary(ctx context.Context) (EOF bool, err error) {
|
|
if e.inputIter != nil && e.inputIter.Current() != e.inputIter.End() {
|
|
return false, nil
|
|
}
|
|
|
|
childResult := newFirstChunk(e.children[0])
|
|
err = Next(ctx, e.children[0], childResult)
|
|
if err != nil {
|
|
return false, errors.Trace(err)
|
|
}
|
|
// No more data.
|
|
numRows := childResult.NumRows()
|
|
if numRows == 0 {
|
|
return true, nil
|
|
}
|
|
|
|
resultChk := chunk.New(e.retFieldTypes, 0, numRows)
|
|
err = e.copyChk(childResult, resultChk)
|
|
if err != nil {
|
|
return false, err
|
|
}
|
|
e.resultChunks = append(e.resultChunks, resultChk)
|
|
e.remainingRowsInChunk = append(e.remainingRowsInChunk, numRows)
|
|
|
|
e.inputIter = chunk.NewIterator4Chunk(childResult)
|
|
e.inputIter.Begin()
|
|
return false, nil
|
|
}
|
|
|
|
func (e *WindowExec) copyChk(src, dst *chunk.Chunk) error {
|
|
columns := e.Schema().Columns[:len(e.Schema().Columns)-e.numWindowFuncs]
|
|
for i, col := range columns {
|
|
if err := dst.MakeRefTo(i, src, col.Index); err != nil {
|
|
return err
|
|
}
|
|
}
|
|
return nil
|
|
}
|
|
|
|
// windowProcessor is the interface for processing different kinds of windows.
|
|
type windowProcessor interface {
|
|
// consumeGroupRows updates the result for an window function using the input rows
|
|
// which belong to the same partition.
|
|
consumeGroupRows(ctx sessionctx.Context, rows []chunk.Row) ([]chunk.Row, error)
|
|
// appendResult2Chunk appends the final results to chunk.
|
|
// It is called when there are no more rows in current partition.
|
|
appendResult2Chunk(ctx sessionctx.Context, rows []chunk.Row, chk *chunk.Chunk, remained int) ([]chunk.Row, error)
|
|
// resetPartialResult resets the partial result to the original state for a specific window function.
|
|
resetPartialResult()
|
|
}
|
|
|
|
type aggWindowProcessor struct {
|
|
windowFuncs []aggfuncs.AggFunc
|
|
partialResults []aggfuncs.PartialResult
|
|
}
|
|
|
|
func (p *aggWindowProcessor) consumeGroupRows(ctx sessionctx.Context, rows []chunk.Row) ([]chunk.Row, error) {
|
|
for i, windowFunc := range p.windowFuncs {
|
|
err := windowFunc.UpdatePartialResult(ctx, rows, p.partialResults[i])
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
}
|
|
rows = rows[:0]
|
|
return rows, nil
|
|
}
|
|
|
|
func (p *aggWindowProcessor) appendResult2Chunk(ctx sessionctx.Context, rows []chunk.Row, chk *chunk.Chunk, remained int) ([]chunk.Row, error) {
|
|
for remained > 0 {
|
|
for i, windowFunc := range p.windowFuncs {
|
|
// TODO: We can extend the agg func interface to avoid the `for` loop here.
|
|
err := windowFunc.AppendFinalResult2Chunk(ctx, p.partialResults[i], chk)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
}
|
|
remained--
|
|
}
|
|
return rows, nil
|
|
}
|
|
|
|
func (p *aggWindowProcessor) resetPartialResult() {
|
|
for i, windowFunc := range p.windowFuncs {
|
|
windowFunc.ResetPartialResult(p.partialResults[i])
|
|
}
|
|
}
|
|
|
|
type rowFrameWindowProcessor struct {
|
|
windowFuncs []aggfuncs.AggFunc
|
|
partialResults []aggfuncs.PartialResult
|
|
start *core.FrameBound
|
|
end *core.FrameBound
|
|
curRowIdx uint64
|
|
}
|
|
|
|
func (p *rowFrameWindowProcessor) getStartOffset(numRows uint64) uint64 {
|
|
if p.start.UnBounded {
|
|
return 0
|
|
}
|
|
switch p.start.Type {
|
|
case ast.Preceding:
|
|
if p.curRowIdx >= p.start.Num {
|
|
return p.curRowIdx - p.start.Num
|
|
}
|
|
return 0
|
|
case ast.Following:
|
|
offset := p.curRowIdx + p.start.Num
|
|
if offset >= numRows {
|
|
return numRows
|
|
}
|
|
return offset
|
|
case ast.CurrentRow:
|
|
return p.curRowIdx
|
|
}
|
|
// It will never reach here.
|
|
return 0
|
|
}
|
|
|
|
func (p *rowFrameWindowProcessor) getEndOffset(numRows uint64) uint64 {
|
|
if p.end.UnBounded {
|
|
return numRows
|
|
}
|
|
switch p.end.Type {
|
|
case ast.Preceding:
|
|
if p.curRowIdx >= p.end.Num {
|
|
return p.curRowIdx - p.end.Num + 1
|
|
}
|
|
return 0
|
|
case ast.Following:
|
|
offset := p.curRowIdx + p.end.Num
|
|
if offset >= numRows {
|
|
return numRows
|
|
}
|
|
return offset + 1
|
|
case ast.CurrentRow:
|
|
return p.curRowIdx + 1
|
|
}
|
|
// It will never reach here.
|
|
return 0
|
|
}
|
|
|
|
func (p *rowFrameWindowProcessor) consumeGroupRows(ctx sessionctx.Context, rows []chunk.Row) ([]chunk.Row, error) {
|
|
return rows, nil
|
|
}
|
|
|
|
// TODO: We can optimize it using sliding window algorithm.
|
|
func (p *rowFrameWindowProcessor) appendResult2Chunk(ctx sessionctx.Context, rows []chunk.Row, chk *chunk.Chunk, remained int) ([]chunk.Row, error) {
|
|
numRows := uint64(len(rows))
|
|
for remained > 0 {
|
|
start := p.getStartOffset(numRows)
|
|
end := p.getEndOffset(numRows)
|
|
p.curRowIdx++
|
|
remained--
|
|
if start >= end {
|
|
for i, windowFunc := range p.windowFuncs {
|
|
err := windowFunc.AppendFinalResult2Chunk(ctx, p.partialResults[i], chk)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
}
|
|
continue
|
|
}
|
|
for i, windowFunc := range p.windowFuncs {
|
|
err := windowFunc.UpdatePartialResult(ctx, rows[start:end], p.partialResults[i])
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
err = windowFunc.AppendFinalResult2Chunk(ctx, p.partialResults[i], chk)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
windowFunc.ResetPartialResult(p.partialResults[i])
|
|
}
|
|
}
|
|
return rows, nil
|
|
}
|
|
|
|
func (p *rowFrameWindowProcessor) resetPartialResult() {
|
|
p.curRowIdx = 0
|
|
}
|
|
|
|
type rangeFrameWindowProcessor struct {
|
|
windowFuncs []aggfuncs.AggFunc
|
|
partialResults []aggfuncs.PartialResult
|
|
start *core.FrameBound
|
|
end *core.FrameBound
|
|
curRowIdx uint64
|
|
lastStartOffset uint64
|
|
lastEndOffset uint64
|
|
orderByCols []*expression.Column
|
|
// expectedCmpResult is used to decide if one value is included in the frame.
|
|
expectedCmpResult int64
|
|
}
|
|
|
|
func (p *rangeFrameWindowProcessor) getStartOffset(ctx sessionctx.Context, rows []chunk.Row) (uint64, error) {
|
|
if p.start.UnBounded {
|
|
return 0, nil
|
|
}
|
|
numRows := uint64(len(rows))
|
|
for ; p.lastStartOffset < numRows; p.lastStartOffset++ {
|
|
var res int64
|
|
var err error
|
|
for i := range p.orderByCols {
|
|
res, _, err = p.start.CmpFuncs[i](ctx, p.orderByCols[i], p.start.CalcFuncs[i], rows[p.lastStartOffset], rows[p.curRowIdx])
|
|
if err != nil {
|
|
return 0, err
|
|
}
|
|
if res != 0 {
|
|
break
|
|
}
|
|
}
|
|
// For asc, break when the current value is greater or equal to the calculated result;
|
|
// For desc, break when the current value is less or equal to the calculated result.
|
|
if res != p.expectedCmpResult {
|
|
break
|
|
}
|
|
}
|
|
return p.lastStartOffset, nil
|
|
}
|
|
|
|
func (p *rangeFrameWindowProcessor) getEndOffset(ctx sessionctx.Context, rows []chunk.Row) (uint64, error) {
|
|
numRows := uint64(len(rows))
|
|
if p.end.UnBounded {
|
|
return numRows, nil
|
|
}
|
|
for ; p.lastEndOffset < numRows; p.lastEndOffset++ {
|
|
var res int64
|
|
var err error
|
|
for i := range p.orderByCols {
|
|
res, _, err = p.end.CmpFuncs[i](ctx, p.end.CalcFuncs[i], p.orderByCols[i], rows[p.curRowIdx], rows[p.lastEndOffset])
|
|
if err != nil {
|
|
return 0, err
|
|
}
|
|
if res != 0 {
|
|
break
|
|
}
|
|
}
|
|
// For asc, break when the calculated result is greater than the current value.
|
|
// For desc, break when the calculated result is less than the current value.
|
|
if res == p.expectedCmpResult {
|
|
break
|
|
}
|
|
}
|
|
return p.lastEndOffset, nil
|
|
}
|
|
|
|
func (p *rangeFrameWindowProcessor) appendResult2Chunk(ctx sessionctx.Context, rows []chunk.Row, chk *chunk.Chunk, remained int) ([]chunk.Row, error) {
|
|
for remained > 0 {
|
|
start, err := p.getStartOffset(ctx, rows)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
end, err := p.getEndOffset(ctx, rows)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
p.curRowIdx++
|
|
remained--
|
|
if start >= end {
|
|
for i, windowFunc := range p.windowFuncs {
|
|
err := windowFunc.AppendFinalResult2Chunk(ctx, p.partialResults[i], chk)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
}
|
|
continue
|
|
}
|
|
for i, windowFunc := range p.windowFuncs {
|
|
err := windowFunc.UpdatePartialResult(ctx, rows[start:end], p.partialResults[i])
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
err = windowFunc.AppendFinalResult2Chunk(ctx, p.partialResults[i], chk)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
windowFunc.ResetPartialResult(p.partialResults[i])
|
|
}
|
|
}
|
|
return rows, nil
|
|
}
|
|
|
|
func (p *rangeFrameWindowProcessor) consumeGroupRows(ctx sessionctx.Context, rows []chunk.Row) ([]chunk.Row, error) {
|
|
return rows, nil
|
|
}
|
|
|
|
func (p *rangeFrameWindowProcessor) resetPartialResult() {
|
|
p.curRowIdx = 0
|
|
p.lastStartOffset = 0
|
|
p.lastEndOffset = 0
|
|
}
|