agg_to_pb.go

// Copyright 2017 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 aggregation

import (
	"strconv"

	"github.com/pingcap/errors"
	"github.com/pingcap/tidb/expression"
	"github.com/pingcap/tidb/kv"
	"github.com/pingcap/tidb/parser/ast"
	"github.com/pingcap/tidb/sessionctx"
	"github.com/pingcap/tidb/sessionctx/variable"
	"github.com/pingcap/tidb/types"
	"github.com/pingcap/tidb/util/codec"
	"github.com/pingcap/tipb/go-tipb"
)

// GetTiPBExpr return the TiPB ExprType of desc.
func (desc *baseFuncDesc) GetTiPBExpr(tryWindowDesc bool) (tp tipb.ExprType) {
	switch desc.Name {
	case ast.AggFuncCount:
		tp = tipb.ExprType_Count
	case ast.AggFuncApproxCountDistinct:
		tp = tipb.ExprType_ApproxCountDistinct
	case ast.AggFuncFirstRow:
		tp = tipb.ExprType_First
	case ast.AggFuncGroupConcat:
		tp = tipb.ExprType_GroupConcat
	case ast.AggFuncMax:
		tp = tipb.ExprType_Max
	case ast.AggFuncMin:
		tp = tipb.ExprType_Min
	case ast.AggFuncSum:
		tp = tipb.ExprType_Sum
	case ast.AggFuncAvg:
		tp = tipb.ExprType_Avg
	case ast.AggFuncBitOr:
		tp = tipb.ExprType_Agg_BitOr
	case ast.AggFuncBitXor:
		tp = tipb.ExprType_Agg_BitXor
	case ast.AggFuncBitAnd:
		tp = tipb.ExprType_Agg_BitAnd
	case ast.AggFuncVarPop:
		tp = tipb.ExprType_VarPop
	case ast.AggFuncJsonArrayagg:
		tp = tipb.ExprType_JsonArrayAgg
	case ast.AggFuncJsonObjectAgg:
		tp = tipb.ExprType_JsonObjectAgg
	case ast.AggFuncStddevPop:
		tp = tipb.ExprType_StddevPop
	case ast.AggFuncVarSamp:
		tp = tipb.ExprType_VarSamp
	case ast.AggFuncStddevSamp:
		tp = tipb.ExprType_StddevSamp
	}

	if tp != tipb.ExprType_Null || !tryWindowDesc {
		return
	}

	switch desc.Name {
	case ast.WindowFuncRowNumber:
		tp = tipb.ExprType_RowNumber
	case ast.WindowFuncRank:
		tp = tipb.ExprType_Rank
	case ast.WindowFuncDenseRank:
		tp = tipb.ExprType_DenseRank
	case ast.WindowFuncCumeDist:
		tp = tipb.ExprType_CumeDist
	case ast.WindowFuncPercentRank:
		tp = tipb.ExprType_PercentRank
	case ast.WindowFuncNtile:
		tp = tipb.ExprType_Ntile
	case ast.WindowFuncLead:
		tp = tipb.ExprType_Lead
	case ast.WindowFuncLag:
		tp = tipb.ExprType_Lag
	case ast.WindowFuncFirstValue:
		tp = tipb.ExprType_FirstValue
	case ast.WindowFuncLastValue:
		tp = tipb.ExprType_LastValue
	case ast.WindowFuncNthValue:
		tp = tipb.ExprType_NthValue
	}
	return tp
}

// AggFuncToPBExpr converts aggregate function to pb.
func AggFuncToPBExpr(sctx sessionctx.Context, client kv.Client, aggFunc *AggFuncDesc, storeType kv.StoreType) (*tipb.Expr, error) {
	pc := expression.NewPBConverter(client, sctx.GetSessionVars().StmtCtx)
	tp := aggFunc.GetTiPBExpr(false)
	if !client.IsRequestTypeSupported(kv.ReqTypeSelect, int64(tp)) {
		return nil, errors.New("select request is not supported by client")
	}

	children := make([]*tipb.Expr, 0, len(aggFunc.Args))
	for _, arg := range aggFunc.Args {
		pbArg := pc.ExprToPB(arg)
		if pbArg == nil {
			return nil, errors.New(aggFunc.String() + " can't be converted to PB.")
		}
		children = append(children, pbArg)
	}
	retType, err := expression.ToPBFieldTypeWithCheck(aggFunc.RetTp, storeType)
	if err != nil {
		return nil, errors.Trace(err)
	}

	if tp == tipb.ExprType_GroupConcat {
		orderBy := make([]*tipb.ByItem, 0, len(aggFunc.OrderByItems))
		sc := sctx.GetSessionVars().StmtCtx
		for _, arg := range aggFunc.OrderByItems {
			pbArg := expression.SortByItemToPB(sc, client, arg.Expr, arg.Desc)
			if pbArg == nil {
				return nil, errors.New(aggFunc.String() + " can't be converted to PB.")
			}
			orderBy = append(orderBy, pbArg)
		}
		// encode GroupConcatMaxLen
		GCMaxLen, err := sctx.GetSessionVars().GetSessionOrGlobalSystemVar(variable.GroupConcatMaxLen)
		if err != nil {
			return nil, errors.Errorf("Error happened when buildGroupConcat: no system variable named '%s'", variable.GroupConcatMaxLen)
		}
		maxLen, err := strconv.ParseUint(GCMaxLen, 10, 64)
		// Should never happen
		if err != nil {
			return nil, errors.Errorf("Error happened when buildGroupConcat: %s", err.Error())
		}
		return &tipb.Expr{Tp: tp, Val: codec.EncodeUint(nil, maxLen), Children: children, FieldType: retType, HasDistinct: aggFunc.HasDistinct, OrderBy: orderBy, AggFuncMode: AggFunctionModeToPB(aggFunc.Mode)}, nil
	}
	return &tipb.Expr{Tp: tp, Children: children, FieldType: retType, HasDistinct: aggFunc.HasDistinct, AggFuncMode: AggFunctionModeToPB(aggFunc.Mode)}, nil
}

// AggFunctionModeToPB converts aggregate function mode to PB.
func AggFunctionModeToPB(mode AggFunctionMode) (pbMode *tipb.AggFunctionMode) {
	pbMode = new(tipb.AggFunctionMode)
	switch mode {
	case CompleteMode:
		*pbMode = tipb.AggFunctionMode_CompleteMode
	case FinalMode:
		*pbMode = tipb.AggFunctionMode_FinalMode
	case Partial1Mode:
		*pbMode = tipb.AggFunctionMode_Partial1Mode
	case Partial2Mode:
		*pbMode = tipb.AggFunctionMode_Partial2Mode
	case DedupMode:
		*pbMode = tipb.AggFunctionMode_DedupMode
	}
	return pbMode
}

// PBAggFuncModeToAggFuncMode converts pb to aggregate function mode.
func PBAggFuncModeToAggFuncMode(pbMode *tipb.AggFunctionMode) (mode AggFunctionMode) {
	// Default mode of the aggregate function is PartialMode.
	mode = Partial1Mode
	if pbMode != nil {
		switch *pbMode {
		case tipb.AggFunctionMode_CompleteMode:
			mode = CompleteMode
		case tipb.AggFunctionMode_FinalMode:
			mode = FinalMode
		case tipb.AggFunctionMode_Partial1Mode:
			mode = Partial1Mode
		case tipb.AggFunctionMode_Partial2Mode:
			mode = Partial2Mode
		case tipb.AggFunctionMode_DedupMode:
			mode = DedupMode
		}
	}
	return mode
}

// PBExprToAggFuncDesc converts pb to aggregate function.
func PBExprToAggFuncDesc(ctx sessionctx.Context, aggFunc *tipb.Expr, fieldTps []*types.FieldType) (*AggFuncDesc, error) {
	var name string
	switch aggFunc.Tp {
	case tipb.ExprType_Count:
		name = ast.AggFuncCount
	case tipb.ExprType_ApproxCountDistinct:
		name = ast.AggFuncApproxCountDistinct
	case tipb.ExprType_First:
		name = ast.AggFuncFirstRow
	case tipb.ExprType_GroupConcat:
		name = ast.AggFuncGroupConcat
	case tipb.ExprType_Max:
		name = ast.AggFuncMax
	case tipb.ExprType_Min:
		name = ast.AggFuncMin
	case tipb.ExprType_Sum:
		name = ast.AggFuncSum
	case tipb.ExprType_Avg:
		name = ast.AggFuncAvg
	case tipb.ExprType_Agg_BitOr:
		name = ast.AggFuncBitOr
	case tipb.ExprType_Agg_BitXor:
		name = ast.AggFuncBitXor
	case tipb.ExprType_Agg_BitAnd:
		name = ast.AggFuncBitAnd
	default:
		return nil, errors.Errorf("unknown aggregation function type: %v", aggFunc.Tp)
	}

	args, err := expression.PBToExprs(aggFunc.Children, fieldTps, ctx.GetSessionVars().StmtCtx)
	if err != nil {
		return nil, err
	}
	base := baseFuncDesc{
		Name:  name,
		Args:  args,
		RetTp: expression.FieldTypeFromPB(aggFunc.FieldType),
	}
	base.WrapCastForAggArgs(ctx)
	return &AggFuncDesc{
		baseFuncDesc: base,
		Mode:         PBAggFuncModeToAggFuncMode(aggFunc.AggFuncMode),
		HasDistinct:  false,
	}, nil
}