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aggfuncs: partially implement "AVG" #6951
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Original file line number | Diff line number | Diff line change |
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@@ -16,6 +16,7 @@ package aggfuncs | |
import ( | ||
"github.com/pingcap/tidb/ast" | ||
"github.com/pingcap/tidb/expression/aggregation" | ||
"github.com/pingcap/tidb/mysql" | ||
) | ||
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// Build is used to build a specific AggFunc implementation according to the | ||
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@@ -58,6 +59,42 @@ func buildSum(aggFuncDesc *aggregation.AggFuncDesc, ordinal int) AggFunc { | |
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// buildCount builds the AggFunc implementation for function "AVG". | ||
There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more.
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func buildAvg(aggFuncDesc *aggregation.AggFuncDesc, ordinal int) AggFunc { | ||
base := baseAggFunc{ | ||
args: aggFuncDesc.Args, | ||
ordinal: ordinal, | ||
} | ||
switch aggFuncDesc.Mode { | ||
// Build avg functions which consume the original data and remove the | ||
// duplicated input of the same group. | ||
case aggregation.DedupMode: | ||
return nil // not implemented yet. | ||
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// Build avg functions which consume the original data and update their | ||
// partial results. | ||
case aggregation.CompleteMode, aggregation.Partial1Mode: | ||
switch aggFuncDesc.Args[0].GetType().Tp { | ||
case mysql.TypeNewDecimal: | ||
if aggFuncDesc.HasDistinct { | ||
There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. Can we check it at the beginning of this function? There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. No, we only need to check this when the aggregate function is on |
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return nil // not implemented yet. | ||
} | ||
return &avgOriginal4Decimal{baseAvgDecimal{base}} | ||
case mysql.TypeFloat, mysql.TypeDouble: | ||
if aggFuncDesc.HasDistinct { | ||
return nil // not implemented yet. | ||
} | ||
return &avgOriginal4Float64{baseAvgFloat64{base}} | ||
} | ||
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// Build avg functions which consume the partial result of other avg | ||
// functions and update their partial results. | ||
case aggregation.Partial2Mode, aggregation.FinalMode: | ||
switch aggFuncDesc.Args[1].GetType().Tp { | ||
case mysql.TypeNewDecimal: | ||
return &avgPartial4Decimal{baseAvgDecimal{base}} | ||
case mysql.TypeDouble: | ||
return &avgPartial4Float64{baseAvgFloat64{base}} | ||
} | ||
} | ||
return nil | ||
} | ||
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Original file line number | Diff line number | Diff line change |
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@@ -0,0 +1,207 @@ | ||
// 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, | ||
// See the License for the specific language governing permissions and | ||
// limitations under the License. | ||
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package aggfuncs | ||
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import ( | ||
"github.com/juju/errors" | ||
"github.com/pingcap/tidb/sessionctx" | ||
"github.com/pingcap/tidb/types" | ||
"github.com/pingcap/tidb/util/chunk" | ||
) | ||
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// All the following avg function implementations return the decimal result, | ||
// which store the partial results in "partialResult4AvgDecimal". | ||
// | ||
// "baseAvgDecimal" is wrapped by: | ||
// - "avgOriginal4Decimal" | ||
// - "avgPartial4Decimal" | ||
type baseAvgDecimal struct { | ||
baseAggFunc | ||
} | ||
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type partialResult4AvgDecimal struct { | ||
sum types.MyDecimal | ||
count int64 | ||
} | ||
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func (e *baseAvgDecimal) AllocPartialResult() PartialResult { | ||
return PartialResult(&partialResult4AvgDecimal{}) | ||
} | ||
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func (e *baseAvgDecimal) ResetPartialResult(pr PartialResult) { | ||
p := (*partialResult4AvgDecimal)(pr) | ||
p.sum = *types.NewDecFromInt(0) | ||
p.count = int64(0) | ||
} | ||
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func (e *baseAvgDecimal) AppendFinalResult2Chunk(sctx sessionctx.Context, pr PartialResult, chk *chunk.Chunk) error { | ||
p := (*partialResult4AvgDecimal)(pr) | ||
if p.count == 0 { | ||
chk.AppendNull(e.ordinal) | ||
return nil | ||
} | ||
decimalCount := types.NewDecFromInt(p.count) | ||
finalResult := new(types.MyDecimal) | ||
err := types.DecimalDiv(&p.sum, decimalCount, finalResult, types.DivFracIncr) | ||
if err != nil { | ||
return errors.Trace(err) | ||
} | ||
chk.AppendMyDecimal(e.ordinal, finalResult) | ||
return nil | ||
} | ||
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type avgOriginal4Decimal struct { | ||
baseAvgDecimal | ||
} | ||
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func (e *avgOriginal4Decimal) UpdatePartialResult(sctx sessionctx.Context, rowsInGroup []chunk.Row, pr PartialResult) error { | ||
p := (*partialResult4AvgDecimal)(pr) | ||
newSum := new(types.MyDecimal) | ||
for _, row := range rowsInGroup { | ||
input, isNull, err := e.args[0].EvalDecimal(sctx, row) | ||
if err != nil { | ||
return errors.Trace(err) | ||
} | ||
if isNull { | ||
continue | ||
} | ||
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err = types.DecimalAdd(&p.sum, input, newSum) | ||
if err != nil { | ||
return errors.Trace(err) | ||
} | ||
p.sum = *newSum | ||
p.count++ | ||
} | ||
return nil | ||
} | ||
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type avgPartial4Decimal struct { | ||
baseAvgDecimal | ||
} | ||
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func (e *avgPartial4Decimal) UpdatePartialResult(sctx sessionctx.Context, rowsInGroup []chunk.Row, pr PartialResult) error { | ||
p := (*partialResult4AvgDecimal)(pr) | ||
newSum := new(types.MyDecimal) | ||
for _, row := range rowsInGroup { | ||
inputSum, isNull, err := e.args[1].EvalDecimal(sctx, row) | ||
if err != nil { | ||
return errors.Trace(err) | ||
} | ||
if isNull { | ||
continue | ||
} | ||
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inputCount, isNull, err := e.args[0].EvalInt(sctx, row) | ||
if err != nil { | ||
return errors.Trace(err) | ||
} | ||
if isNull { | ||
continue | ||
} | ||
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err = types.DecimalAdd(&p.sum, inputSum, newSum) | ||
if err != nil { | ||
return errors.Trace(err) | ||
} | ||
p.sum = *newSum | ||
p.count += inputCount | ||
} | ||
return nil | ||
} | ||
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// All the following avg function implementations return the float64 result, | ||
// which store the partial results in "partialResult4AvgFloat64". | ||
// | ||
// "baseAvgFloat64" is wrapped by: | ||
// - "avgOriginal4Float64" | ||
// - "avgPartial4Float64" | ||
type baseAvgFloat64 struct { | ||
baseAggFunc | ||
} | ||
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type partialResult4AvgFloat64 struct { | ||
sum float64 | ||
count int64 | ||
} | ||
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func (e *baseAvgFloat64) AllocPartialResult() PartialResult { | ||
return (PartialResult)(&partialResult4AvgFloat64{}) | ||
} | ||
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func (e *baseAvgFloat64) ResetPartialResult(pr PartialResult) { | ||
p := (*partialResult4AvgFloat64)(pr) | ||
p.sum = 0 | ||
p.count = 0 | ||
} | ||
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func (e *baseAvgFloat64) AppendFinalResult2Chunk(sctx sessionctx.Context, pr PartialResult, chk *chunk.Chunk) error { | ||
p := (*partialResult4AvgFloat64)(pr) | ||
if p.count == 0 { | ||
chk.AppendNull(e.ordinal) | ||
} else { | ||
chk.AppendFloat64(e.ordinal, p.sum/float64(p.count)) | ||
} | ||
return nil | ||
} | ||
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type avgOriginal4Float64 struct { | ||
baseAvgFloat64 | ||
} | ||
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func (e *avgOriginal4Float64) UpdatePartialResult(sctx sessionctx.Context, rowsInGroup []chunk.Row, pr PartialResult) error { | ||
p := (*partialResult4AvgFloat64)(pr) | ||
for _, row := range rowsInGroup { | ||
input, isNull, err := e.args[0].EvalReal(sctx, row) | ||
if err != nil { | ||
return errors.Trace(err) | ||
} | ||
if isNull { | ||
continue | ||
} | ||
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p.sum += input | ||
p.count++ | ||
} | ||
return nil | ||
} | ||
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type avgPartial4Float64 struct { | ||
baseAvgFloat64 | ||
} | ||
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func (e *avgPartial4Float64) UpdatePartialResult(sctx sessionctx.Context, rowsInGroup []chunk.Row, pr PartialResult) error { | ||
p := (*partialResult4AvgFloat64)(pr) | ||
for _, row := range rowsInGroup { | ||
inputSum, isNull, err := e.args[1].EvalReal(sctx, row) | ||
if err != nil { | ||
return errors.Trace(err) | ||
} | ||
if isNull { | ||
continue | ||
} | ||
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inputCount, isNull, err := e.args[0].EvalInt(sctx, row) | ||
if err != nil { | ||
return errors.Trace(err) | ||
} | ||
if isNull { | ||
continue | ||
} | ||
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p.sum += inputSum | ||
p.count += inputCount | ||
} | ||
return nil | ||
} |
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Why name it Original?
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means this aggregate function is in the
partial 1
orcomplete
mode and it's input is the data from the child of logical aggregate operator, not the partial result of other aggregate function.There was a problem hiding this comment.
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How about
avg4Decimal
?There was a problem hiding this comment.
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avg4Decimal
maybe confusing withavgPartial4Decimal
, I prefer the old name.