func (e *XSelectIndexExec) doIndexRequest() (*xapi.SelectResult, error) {
	txn, err := e.ctx.GetTxn(false)
	if err != nil {
		return nil, errors.Trace(err)
	}
	selIdxReq := new(tipb.SelectRequest)
	startTs := txn.StartTS()
	selIdxReq.StartTs = &startTs
	selIdxReq.IndexInfo = xapi.IndexToProto(e.table.Meta(), e.indexPlan.Index)
	if len(e.indexPlan.FilterConditions) == 0 {
		// Push limit to index request only if there is not filter conditions.
		selIdxReq.Limit = e.indexPlan.LimitCount
	}
	if e.indexPlan.Desc {
		selIdxReq.OrderBy = append(selIdxReq.OrderBy, &tipb.ByItem{Desc: &e.indexPlan.Desc})
	}
	fieldTypes := make([]*types.FieldType, len(e.indexPlan.Index.Columns))
	for i, v := range e.indexPlan.Index.Columns {
		fieldTypes[i] = &(e.table.Cols()[v.Offset].FieldType)
	}
	selIdxReq.Ranges, err = indexRangesToPBRanges(e.indexPlan.Ranges, fieldTypes)
	if err != nil {
		return nil, errors.Trace(err)
	}
	concurrency := 1
	if e.indexPlan.OutOfOrder {
		concurrency = 10
	}
	return xapi.Select(txn.GetClient(), selIdxReq, concurrency)
}

func (e *NewXSelectTableExec) doRequest() error {
	txn, err := e.ctx.GetTxn(false)
	if err != nil {
		return errors.Trace(err)
	}
	selReq := new(tipb.SelectRequest)
	startTs := txn.StartTS()
	selReq.StartTs = &startTs
	selReq.Where = e.where
	selReq.Ranges = tableRangesToPBRanges(e.ranges)
	columns := e.Columns
	selReq.TableInfo = &tipb.TableInfo{
		TableId: proto.Int64(e.tableInfo.ID),
	}
	if e.supportDesc && e.desc {
		selReq.OrderBy = append(selReq.OrderBy, &tipb.ByItem{Desc: &e.desc})
	}
	selReq.Limit = e.limitCount
	selReq.TableInfo.Columns = xapi.ColumnsToProto(columns, e.tableInfo.PKIsHandle)
	// Aggregate Info
	selReq.Aggregates = e.aggFuncs
	selReq.GroupBy = e.byItems
	e.result, err = xapi.Select(txn.GetClient(), selReq, defaultConcurrency)
	if err != nil {
		return errors.Trace(err)
	}
	//if len(selReq.Aggregates) > 0 || len(selReq.GroupBy) > 0 {
	if e.aggregate {
		// The returned rows should be aggregate partial result.
		e.result.SetFields(e.aggFields)
	}
	return nil
}

func (e *NewXSelectIndexExec) doTableRequest(handles []int64) (*xapi.SelectResult, error) {
	txn, err := e.ctx.GetTxn(false)
	if err != nil {
		return nil, errors.Trace(err)
	}
	// The handles are not in original index order, so we can't push limit here.
	selTableReq := new(tipb.SelectRequest)
	startTs := txn.StartTS()
	selTableReq.StartTs = &startTs
	selTableReq.TableInfo = &tipb.TableInfo{
		TableId: proto.Int64(e.table.Meta().ID),
	}
	selTableReq.TableInfo.Columns = xapi.ColumnsToProto(e.indexPlan.Columns, e.table.Meta().PKIsHandle)
	for _, h := range handles {
		if h == math.MaxInt64 {
			// We can't convert MaxInt64 into an left closed, right open range.
			continue
		}
		pbRange := new(tipb.KeyRange)
		pbRange.Low = codec.EncodeInt(nil, h)
		pbRange.High = kv.Key(pbRange.Low).PrefixNext()
		selTableReq.Ranges = append(selTableReq.Ranges, pbRange)
	}
	selTableReq.Where = e.where
	// Aggregate Info
	resp, err := xapi.Select(txn.GetClient(), selTableReq, defaultConcurrency)
	if err != nil {
		return nil, errors.Trace(err)
	}
	return resp, nil
}

func (e *XSelectIndexExec) doIndexRequest() (xapi.SelectResult, error) {
	selIdxReq := new(tipb.SelectRequest)
	selIdxReq.StartTs = e.txn.StartTS()
	selIdxReq.IndexInfo = xapi.IndexToProto(e.table.Meta(), e.indexPlan.Index)
	if e.indexPlan.Desc {
		selIdxReq.OrderBy = append(selIdxReq.OrderBy, &tipb.ByItem{Desc: e.indexPlan.Desc})
	}
	fieldTypes := make([]*types.FieldType, len(e.indexPlan.Index.Columns))
	for i, v := range e.indexPlan.Index.Columns {
		fieldTypes[i] = &(e.table.Cols()[v.Offset].FieldType)
	}
	if !e.indexPlan.DoubleRead || e.where == nil {
		// TODO: when where condition is all index columns limit can be pushed too.
		selIdxReq.Limit = e.indexPlan.LimitCount
	}
	concurrency := 1
	if !e.indexPlan.DoubleRead {
		concurrency = defaultConcurrency
		selIdxReq.Aggregates = e.aggFuncs
		selIdxReq.GroupBy = e.byItems
		selIdxReq.Where = e.where
	} else if e.indexPlan.OutOfOrder {
		concurrency = defaultConcurrency
	}
	keyRanges, err := indexRangesToKVRanges(e.table.Meta().ID, e.indexPlan.Index.ID, e.indexPlan.Ranges, fieldTypes)
	if err != nil {
		return nil, errors.Trace(err)
	}
	return xapi.Select(e.txn.GetClient(), selIdxReq, keyRanges, concurrency, !e.indexPlan.OutOfOrder)
}

func (e *XSelectTableExec) doRequest() error {
	var err error
	selReq := new(tipb.SelectRequest)
	selReq.StartTs = e.txn.StartTS()
	selReq.Where = e.where
	columns := e.Columns
	selReq.TableInfo = &tipb.TableInfo{
		TableId: e.tableInfo.ID,
	}
	if e.supportDesc && e.desc {
		selReq.OrderBy = append(selReq.OrderBy, &tipb.ByItem{Desc: e.desc})
	}
	selReq.Limit = e.limitCount
	selReq.TableInfo.Columns = xapi.ColumnsToProto(columns, e.tableInfo.PKIsHandle)
	// Aggregate Info
	selReq.Aggregates = e.aggFuncs
	selReq.GroupBy = e.byItems

	kvRanges := tableRangesToKVRanges(e.table.Meta().ID, e.ranges)
	e.result, err = xapi.Select(e.txn.GetClient(), selReq, kvRanges, defaultConcurrency, e.keepOrder)
	if err != nil {
		return errors.Trace(err)
	}
	//if len(selReq.Aggregates) > 0 || len(selReq.GroupBy) > 0 {
	if e.aggregate {
		// The returned rows should be aggregate partial result.
		e.result.SetFields(e.aggFields)
	}
	e.result.Fetch()
	return nil
}

func (e *XSelectIndexExec) doTableRequest(handles []int64) (xapi.SelectResult, error) {
	// The handles are not in original index order, so we can't push limit here.
	selTableReq := new(tipb.SelectRequest)
	if e.indexPlan.OutOfOrder {
		selTableReq.Limit = e.indexPlan.LimitCount
	}
	selTableReq.StartTs = e.txn.StartTS()
	selTableReq.TableInfo = &tipb.TableInfo{
		TableId: e.table.Meta().ID,
	}
	selTableReq.TableInfo.Columns = xapi.ColumnsToProto(e.indexPlan.Columns, e.table.Meta().PKIsHandle)
	selTableReq.Where = e.where
	// Aggregate Info
	selTableReq.Aggregates = e.aggFuncs
	selTableReq.GroupBy = e.byItems
	keyRanges := tableHandlesToKVRanges(e.table.Meta().ID, handles)
	resp, err := xapi.Select(e.txn.GetClient(), selTableReq, keyRanges, defaultConcurrency, false)
	if err != nil {
		return nil, errors.Trace(err)
	}
	if e.aggregate {
		// The returned rows should be aggregate partial result.
		resp.SetFields(e.aggFields)
	}
	resp.Fetch()
	return resp, nil
}

func (e *NewXSelectIndexExec) doTableRequest(handles []int64) (xapi.SelectResult, error) {
	// The handles are not in original index order, so we can't push limit here.
	selTableReq := new(tipb.SelectRequest)
	selTableReq.StartTs = e.txn.StartTS()
	selTableReq.TableInfo = &tipb.TableInfo{
		TableId: e.table.Meta().ID,
	}
	selTableReq.TableInfo.Columns = xapi.ColumnsToProto(e.indexPlan.Columns, e.table.Meta().PKIsHandle)
	for _, h := range handles {
		if h == math.MaxInt64 {
			// We can't convert MaxInt64 into an left closed, right open range.
			continue
		}
		pbRange := new(tipb.KeyRange)
		pbRange.Low = codec.EncodeInt(nil, h)
		pbRange.High = kv.Key(pbRange.Low).PrefixNext()
		selTableReq.Ranges = append(selTableReq.Ranges, pbRange)
	}
	selTableReq.Where = e.where
	// Aggregate Info
	selTableReq.Aggregates = e.aggFuncs
	selTableReq.GroupBy = e.byItems
	// Aggregate Info
	resp, err := xapi.Select(e.txn.GetClient(), selTableReq, defaultConcurrency, false)
	if err != nil {
		return nil, errors.Trace(err)
	}
	if e.aggregate {
		// The returned rows should be aggregate partial result.
		resp.SetFields(e.aggFields)
	}
	resp.Fetch()
	return resp, nil
}

func (e *XSelectIndexExec) doIndexRequest(txn kv.Transaction) (*xapi.SelectResult, error) {
	selIdxReq := new(tipb.SelectRequest)
	startTs := txn.StartTS()
	selIdxReq.StartTs = &startTs
	selIdxReq.IndexInfo = tablecodec.IndexToProto(e.table.Meta(), e.indexPlan.Index)
	var err error
	selIdxReq.Ranges, err = indexRangesToPBRanges(e.indexPlan.Ranges)
	if err != nil {
		return nil, errors.Trace(err)
	}
	return xapi.Select(txn.GetClient(), selIdxReq, 1)
}

func (e *XSelectTableExec) doRequest() error {
	txn, err := e.ctx.GetTxn(false)
	if err != nil {
		return errors.Trace(err)
	}
	selReq := new(tipb.SelectRequest)
	startTs := txn.StartTS()
	selReq.StartTs = &startTs
	selReq.Fields = resultFieldsToPBExpression(e.tablePlan.Fields())
	selReq.Where = conditionsToPBExpression(e.tablePlan.FilterConditions...)
	selReq.Ranges = tableRangesToPBRanges(e.tablePlan.Ranges)
	selReq.TableInfo = tablecodec.TableToProto(e.tablePlan.Table)
	e.result, err = xapi.Select(txn.GetClient(), selReq, 1)
	if err != nil {
		return errors.Trace(err)
	}
	return nil
}

func (e *XSelectIndexExec) doTableRequest(handles []int64) (*xapi.SelectResult, error) {
	txn, err := e.ctx.GetTxn(false)
	if err != nil {
		return nil, errors.Trace(err)
	}
	// The handles are not in original index order, so we can't push limit here.
	selTableReq := new(tipb.SelectRequest)
	startTs := txn.StartTS()
	selTableReq.StartTs = &startTs
	columns := make([]*model.ColumnInfo, 0, len(e.indexPlan.Fields()))
	for _, v := range e.indexPlan.Fields() {
		if v.Referenced {
			columns = append(columns, v.Column)
		}
	}
	selTableReq.TableInfo = &tipb.TableInfo{
		TableId: proto.Int64(e.table.Meta().ID),
	}
	selTableReq.TableInfo.Columns = xapi.ColumnsToProto(columns, e.table.Meta().PKIsHandle)
	selTableReq.Fields = resultFieldsToPBExpression(e.indexPlan.Fields())
	for _, h := range handles {
		if h == math.MaxInt64 {
			// We can't convert MaxInt64 into an left closed, right open range.
			continue
		}
		pbRange := new(tipb.KeyRange)
		pbRange.Low = codec.EncodeInt(nil, h)
		pbRange.High = kv.Key(pbRange.Low).PrefixNext()
		selTableReq.Ranges = append(selTableReq.Ranges, pbRange)
	}
	selTableReq.Where = e.where
	// Aggregate Info
	selTableReq.Aggregates = e.aggFuncs
	selTableReq.GroupBy = e.byItems
	resp, err := xapi.Select(txn.GetClient(), selTableReq, defaultConcurrency)
	if err != nil {
		return nil, errors.Trace(err)
	}
	if e.aggregate {
		// The returned rows should be aggregate partial result.
		resp.SetFields(e.aggFields)
	}
	return resp, nil
}

func (e *XSelectTableExec) doRequest() error {
	txn, err := e.ctx.GetTxn(false)
	if err != nil {
		return errors.Trace(err)
	}
	selReq := new(tipb.SelectRequest)
	startTs := txn.StartTS()
	selReq.StartTs = &startTs
	selReq.Fields = resultFieldsToPBExpression(e.tablePlan.Fields())
	selReq.Where = e.where
	selReq.Ranges = tableRangesToPBRanges(e.tablePlan.Ranges)
	if e.supportDesc {
		if e.tablePlan.Desc {
			selReq.OrderBy = append(selReq.OrderBy, &tipb.ByItem{Desc: &e.tablePlan.Desc})
		}
		// Limit can be pushed only if desc is supported.
		if e.allFiltersPushed {
			selReq.Limit = e.tablePlan.LimitCount
		}
	}
	columns := make([]*model.ColumnInfo, 0, len(e.tablePlan.Fields()))
	for _, v := range e.tablePlan.Fields() {
		if v.Referenced {
			columns = append(columns, v.Column)
		}
	}
	selReq.TableInfo = &tipb.TableInfo{
		TableId: proto.Int64(e.table.Meta().ID),
	}
	selReq.TableInfo.Columns = xapi.ColumnsToProto(columns, e.table.Meta().PKIsHandle)
	// Aggregate Info
	selReq.Aggregates = e.aggFuncs
	selReq.GroupBy = e.byItems
	e.result, err = xapi.Select(txn.GetClient(), selReq, defaultConcurrency)
	if err != nil {
		return errors.Trace(err)
	}
	if len(selReq.Aggregates) > 0 || len(selReq.GroupBy) > 0 {
		// The returned rows should be aggregate partial result.
		e.result.SetFields(e.aggFields)
	}
	return nil
}

func (e *XSelectIndexExec) doTableRequest(txn kv.Transaction, handles []int64) (*xapi.SelectResult, error) {
	selTableReq := new(tipb.SelectRequest)
	startTs := txn.StartTS()
	selTableReq.StartTs = &startTs
	selTableReq.TableInfo = tablecodec.TableToProto(e.indexPlan.Table)
	selTableReq.Fields = resultFieldsToPBExpression(e.indexPlan.Fields())
	for _, h := range handles {
		if h == math.MaxInt64 {
			// We can't convert MaxInt64 into an left closed, right open range.
			continue
		}
		pbRange := new(tipb.KeyRange)
		pbRange.Low = codec.EncodeInt(nil, h)
		pbRange.High = codec.EncodeInt(nil, h)
		selTableReq.Ranges = append(selTableReq.Ranges, pbRange)
	}
	selTableReq.Where = conditionsToPBExpression(e.indexPlan.FilterConditions...)
	return xapi.Select(txn.GetClient(), selTableReq, 10)
}

func (e *NewTableScanExec) doRequest() error {
	txn, err := e.ctx.GetTxn(false)
	if err != nil {
		return errors.Trace(err)
	}
	selReq := new(tipb.SelectRequest)
	startTs := txn.StartTS()
	selReq.StartTs = &startTs
	selReq.Where = e.where
	selReq.Ranges = tableRangesToPBRanges(e.ranges)
	columns := e.Columns
	selReq.TableInfo = &tipb.TableInfo{
		TableId: proto.Int64(e.tableInfo.ID),
	}
	selReq.TableInfo.Columns = tablecodec.ColumnsToProto(columns, e.tableInfo.PKIsHandle)
	e.result, err = xapi.Select(txn.GetClient(), selReq, defaultConcurrency)
	if err != nil {
		return errors.Trace(err)
	}
	return nil
}