executor: introduce a new execution framework for aggregate functions

executor/aggfuncs/aggfuncs.go

@@ -0,0 +1,61 @@
+// 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.
+
+package aggfuncs
+
+import (
+	"github.com/pingcap/tidb/expression"
+	"github.com/pingcap/tidb/sessionctx"
+	"github.com/pingcap/tidb/util/chunk"
+)
+
+// All the AggFunc implementations are listed here for navigation.
+var (
+	// All the AggFunc implementations for "COUNT".
+	// All the AggFunc implementations for "SUM".
+	// All the AggFunc implementations for "AVG".
+	_ AggFunc = (*avgDedup4Decimal)(nil)
+	_ AggFunc = (*avgOriginal4Decimal)(nil)
+	_ AggFunc = (*avgPartial4Decimal)(nil)
+
+	_ AggFunc = (*avgDedup4Float64)(nil)
+	_ AggFunc = (*avgOriginal4Float64)(nil)
+	_ AggFunc = (*avgPartial4Float64)(nil)
+
+	_ AggFunc = (*avgDedup4Float32)(nil)
+	_ AggFunc = (*avgOriginal4Float32)(nil)
+	_ AggFunc = (*avgPartial4Float32)(nil)
+
+	// All the AggFunc implementations for "FIRSTROW".
+	// All the AggFunc implementations for "MAX".
+	// All the AggFunc implementations for "MIN".
+	// All the AggFunc implementations for "GROUP_CONCAT".
+	// All the AggFunc implementations for "BIT_OR".
+	// All the AggFunc implementations for "BIT_XOR".
+	// All the AggFunc implementations for "BIT_AND".
+)
+
+// AggFunc is the interface to evaluate aggregate functions.
+type AggFunc interface {
+	AllocPartialResult() []byte
+	ResetPartialResult(partialBytes []byte)
+	UpdatePartialResult(sctx sessionctx.Context, rowsInGroup []chunk.Row, partialBytes []byte) error
+
+	AppendPartialResult2Chunk(sctx sessionctx.Context, partialBytes []byte, chk *chunk.Chunk) error
+	AppendFinalResult2Chunk(sctx sessionctx.Context, partialBytes []byte, chk *chunk.Chunk) error
+}
+
+type baseAggFunc struct {
+	input  []expression.Expression
+	output []int
+}

executor/aggfuncs/builder.go

@@ -0,0 +1,141 @@
+// 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.
+
+package aggfuncs
+
+import (
+	"github.com/pingcap/tidb/ast"
+	"github.com/pingcap/tidb/expression/aggregation"
+	"github.com/pingcap/tidb/mysql"
+	"github.com/pingcap/tidb/types"
+)
+
+// Build is used to build AggFunc according to the aggFuncDesc
+func Build(aggFuncDesc *aggregation.AggFuncDesc, output []int) AggFunc {
+	switch aggFuncDesc.Name {
+	case ast.AggFuncCount:
+		return buildCount(aggFuncDesc, output)
+	case ast.AggFuncSum:
+		return buildSum(aggFuncDesc, output)
+	case ast.AggFuncAvg:
+		return buildAvg(aggFuncDesc, output)
+	case ast.AggFuncFirstRow:
+		return buildFirstRow(aggFuncDesc, output)
+	case ast.AggFuncMax:
+		return buildMax(aggFuncDesc, output)
+	case ast.AggFuncMin:
+		return buildMin(aggFuncDesc, output)
+	case ast.AggFuncGroupConcat:
+		return buildGroupConcat(aggFuncDesc, output)
+	case ast.AggFuncBitOr:
+		return buildBitOr(aggFuncDesc, output)
+	case ast.AggFuncBitXor:
+		return buildBitXor(aggFuncDesc, output)
+	case ast.AggFuncBitAnd:
+		return buildBitAnd(aggFuncDesc, output)
+	}
+	return nil
+}
+
+func buildCount(aggFuncDesc *aggregation.AggFuncDesc, output []int) AggFunc {
+	return nil
+}
+
+func buildSum(aggFuncDesc *aggregation.AggFuncDesc, output []int) AggFunc {
+	return nil
+}
+
+func buildAvg(aggFuncDesc *aggregation.AggFuncDesc, output []int) AggFunc {
+	base := baseAggFunc{
+		input:  aggFuncDesc.Args,
+		output: output,
+	}
+
+	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
+		// TODO: implement UpdatePartialResult for the following structs.
+		// switch aggFuncDesc.Args[0].GetType().Tp {
+		// case mysql.TypeDecimal:
+		// 	return &avgDedup4Decimal{baseAvgDecimal{base}}
+		// case mysql.TypeFloat:
+		// 	return &avgDedup4Float32{baseAvgFloat32{base}}
+		// case mysql.TypeDouble:
+		// 	return &avgDedup4Float64{baseAvgFloat64{base}}
+		// }
+
+	// 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 {
+				return &avgOriginal4Decimal{baseAvgDecimal{base}, make(map[types.MyDecimal]bool)}
+			}
+			return &avgOriginal4Decimal{baseAvgDecimal{base}, nil}
+		case mysql.TypeFloat:
+			if aggFuncDesc.HasDistinct {
+				return &avgOriginal4Float32{baseAvgFloat32{base}, make(map[float32]bool)}
+			}
+			return &avgOriginal4Float32{baseAvgFloat32{base}, nil}
+		case mysql.TypeDouble:
+			if aggFuncDesc.HasDistinct {
+				return &avgOriginal4Float64{baseAvgFloat64{base}, make(map[float64]bool)}
+			}
+			return &avgOriginal4Float64{baseAvgFloat64{base}, nil}
+		}
+
+	// Build avg functions which consume the partial result of other agg
+	// 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.TypeFloat:
+			return &avgPartial4Float32{baseAvgFloat32{base}}
+		case mysql.TypeDouble:
+			return &avgPartial4Float64{baseAvgFloat64{base}}
+		}
+	}
+	return nil
+}
+
+func buildFirstRow(aggFuncDesc *aggregation.AggFuncDesc, output []int) AggFunc {
+	return nil
+}
+
+func buildMax(aggFuncDesc *aggregation.AggFuncDesc, output []int) AggFunc {
+	return nil
+}
+
+func buildMin(aggFuncDesc *aggregation.AggFuncDesc, output []int) AggFunc {
+	return nil
+}
+
+func buildGroupConcat(aggFuncDesc *aggregation.AggFuncDesc, output []int) AggFunc {
+	return nil
+}
+
+func buildBitOr(aggFuncDesc *aggregation.AggFuncDesc, output []int) AggFunc {
+	return nil
+}
+
+func buildBitXor(aggFuncDesc *aggregation.AggFuncDesc, output []int) AggFunc {
+	return nil
+}
+
+func buildBitAnd(aggFuncDesc *aggregation.AggFuncDesc, output []int) AggFunc {
+	return nil
+}