diff --git a/go/vt/vtgate/engine/cached_size.go b/go/vt/vtgate/engine/cached_size.go
index e348cfb7a41..7fc342d4513 100644
--- a/go/vt/vtgate/engine/cached_size.go
+++ b/go/vt/vtgate/engine/cached_size.go
@@ -395,9 +395,9 @@ func (cached *OrderedAggregate) CachedSize(alloc bool) int64 {
 			size += elem.CachedSize(false)
 		}
 	}
-	// field Keys []int
+	// field GroupByKeys []vitess.io/vitess/go/vt/vtgate/engine.GroupbyParams
 	{
-		size += int64(cap(cached.Keys)) * int64(8)
+		size += int64(cap(cached.GroupByKeys)) * int64(24)
 	}
 	// field Input vitess.io/vitess/go/vt/vtgate/engine.Primitive
 	if cc, ok := cached.Input.(cachedObject); ok {
diff --git a/go/vt/vtgate/engine/ordered_aggregate.go b/go/vt/vtgate/engine/ordered_aggregate.go
index ca59f16a981..c24968dfb49 100644
--- a/go/vt/vtgate/engine/ordered_aggregate.go
+++ b/go/vt/vtgate/engine/ordered_aggregate.go
@@ -45,9 +45,9 @@ type OrderedAggregate struct {
 	// aggregation function: function opcode and input column number.
 	Aggregates []AggregateParams
 
-	// Keys specifies the input values that must be used for
+	// GroupByKeys specifies the input values that must be used for
 	// the aggregation key.
-	Keys []int
+	GroupByKeys []GroupbyParams
 
 	// TruncateColumnCount specifies the number of columns to return
 	// in the final result. Rest of the columns are truncated
@@ -58,6 +58,17 @@ type OrderedAggregate struct {
 	Input Primitive
 }
 
+// GroupbyParams specify the grouping key to be used.
+type GroupbyParams struct {
+	Col             int
+	WeightStringCol int
+	KeyCol          int
+}
+
+func (gbp GroupbyParams) String() string {
+	return strconv.Itoa(gbp.KeyCol)
+}
+
 // AggregateParams specify the parameters for each aggregation.
 // It contains the opcode and input column number.
 type AggregateParams struct {
@@ -201,7 +212,7 @@ func (oa *OrderedAggregate) execute(vcursor VCursor, bindVars map[string]*queryp
 		current, curDistinct = oa.convertRow(row)
 	}
 
-	if len(result.Rows) == 0 && len(oa.Keys) == 0 {
+	if len(result.Rows) == 0 && len(oa.GroupByKeys) == 0 {
 		// When doing aggregation without grouping keys, we need to produce a single row containing zero-value for the
 		// different aggregation functions
 		row, err := oa.createEmptyRow()
@@ -350,10 +361,18 @@ func (oa *OrderedAggregate) NeedsTransaction() bool {
 }
 
 func (oa *OrderedAggregate) keysEqual(row1, row2 []sqltypes.Value) (bool, error) {
-	for _, key := range oa.Keys {
-		cmp, err := evalengine.NullsafeCompare(row1[key], row2[key])
+	for _, key := range oa.GroupByKeys {
+		cmp, err := evalengine.NullsafeCompare(row1[key.KeyCol], row2[key.KeyCol])
 		if err != nil {
-			return false, err
+			_, isComparisonErr := err.(evalengine.UnsupportedComparisonError)
+			if !(isComparisonErr && key.WeightStringCol != -1) {
+				return false, err
+			}
+			key.KeyCol = key.WeightStringCol
+			cmp, err = evalengine.NullsafeCompare(row1[key.WeightStringCol], row2[key.WeightStringCol])
+			if err != nil {
+				return false, err
+			}
 		}
 		if cmp != 0 {
 			return false, nil
@@ -450,13 +469,13 @@ func aggregateParamsToString(in interface{}) string {
 	return in.(AggregateParams).String()
 }
 
-func intToString(i interface{}) string {
-	return strconv.Itoa(i.(int))
+func groupByParamsToString(i interface{}) string {
+	return i.(GroupbyParams).String()
 }
 
 func (oa *OrderedAggregate) description() PrimitiveDescription {
 	aggregates := GenericJoin(oa.Aggregates, aggregateParamsToString)
-	groupBy := GenericJoin(oa.Keys, intToString)
+	groupBy := GenericJoin(oa.GroupByKeys, groupByParamsToString)
 	other := map[string]interface{}{
 		"Aggregates": aggregates,
 		"GroupBy":    groupBy,
diff --git a/go/vt/vtgate/engine/ordered_aggregate_test.go b/go/vt/vtgate/engine/ordered_aggregate_test.go
index 045291e0e43..45290eceeeb 100644
--- a/go/vt/vtgate/engine/ordered_aggregate_test.go
+++ b/go/vt/vtgate/engine/ordered_aggregate_test.go
@@ -53,8 +53,8 @@ func TestOrderedAggregateExecute(t *testing.T) {
 			Opcode: AggregateCount,
 			Col:    1,
 		}},
-		Keys:  []int{0},
-		Input: fp,
+		GroupByKeys: []GroupbyParams{{KeyCol: 0}},
+		Input:       fp,
 	}
 
 	result, err := oa.Execute(nil, nil, false)
@@ -90,7 +90,7 @@ func TestOrderedAggregateExecuteTruncate(t *testing.T) {
 			Opcode: AggregateCount,
 			Col:    1,
 		}},
-		Keys:                []int{2},
+		GroupByKeys:         []GroupbyParams{{KeyCol: 2}},
 		TruncateColumnCount: 2,
 		Input:               fp,
 	}
@@ -132,8 +132,8 @@ func TestOrderedAggregateStreamExecute(t *testing.T) {
 			Opcode: AggregateCount,
 			Col:    1,
 		}},
-		Keys:  []int{0},
-		Input: fp,
+		GroupByKeys: []GroupbyParams{{KeyCol: 0}},
+		Input:       fp,
 	}
 
 	var results []*sqltypes.Result
@@ -175,7 +175,7 @@ func TestOrderedAggregateStreamExecuteTruncate(t *testing.T) {
 			Opcode: AggregateCount,
 			Col:    1,
 		}},
-		Keys:                []int{2},
+		GroupByKeys:         []GroupbyParams{{KeyCol: 2}},
 		TruncateColumnCount: 2,
 		Input:               fp,
 	}
@@ -316,8 +316,8 @@ func TestOrderedAggregateExecuteCountDistinct(t *testing.T) {
 			Opcode: AggregateCount,
 			Col:    2,
 		}},
-		Keys:  []int{0},
-		Input: fp,
+		GroupByKeys: []GroupbyParams{{KeyCol: 0}},
+		Input:       fp,
 	}
 
 	result, err := oa.Execute(nil, nil, false)
@@ -392,8 +392,8 @@ func TestOrderedAggregateStreamCountDistinct(t *testing.T) {
 			Opcode: AggregateCount,
 			Col:    2,
 		}},
-		Keys:  []int{0},
-		Input: fp,
+		GroupByKeys: []GroupbyParams{{KeyCol: 0}},
+		Input:       fp,
 	}
 
 	var results []*sqltypes.Result
@@ -480,8 +480,8 @@ func TestOrderedAggregateSumDistinctGood(t *testing.T) {
 			Opcode: AggregateSum,
 			Col:    2,
 		}},
-		Keys:  []int{0},
-		Input: fp,
+		GroupByKeys: []GroupbyParams{{KeyCol: 0}},
+		Input:       fp,
 	}
 
 	result, err := oa.Execute(nil, nil, false)
@@ -525,8 +525,8 @@ func TestOrderedAggregateSumDistinctTolerateError(t *testing.T) {
 			Col:    1,
 			Alias:  "sum(distinct col2)",
 		}},
-		Keys:  []int{0},
-		Input: fp,
+		GroupByKeys: []GroupbyParams{{KeyCol: 0}},
+		Input:       fp,
 	}
 
 	result, err := oa.Execute(nil, nil, false)
@@ -560,8 +560,8 @@ func TestOrderedAggregateKeysFail(t *testing.T) {
 			Opcode: AggregateCount,
 			Col:    1,
 		}},
-		Keys:  []int{0},
-		Input: fp,
+		GroupByKeys: []GroupbyParams{{KeyCol: 0}},
+		Input:       fp,
 	}
 
 	want := "types are not comparable: VARCHAR vs VARCHAR"
@@ -593,8 +593,8 @@ func TestOrderedAggregateMergeFail(t *testing.T) {
 			Opcode: AggregateCount,
 			Col:    1,
 		}},
-		Keys:  []int{0},
-		Input: fp,
+		GroupByKeys: []GroupbyParams{{KeyCol: 0}},
+		Input:       fp,
 	}
 
 	result := &sqltypes.Result{
@@ -721,8 +721,8 @@ func TestNoInputAndNoGroupingKeys(outer *testing.T) {
 					Col:    0,
 					Alias:  test.name,
 				}},
-				Keys:  []int{},
-				Input: fp,
+				GroupByKeys: []GroupbyParams{},
+				Input:       fp,
 			}
 
 			result, err := oa.Execute(nil, nil, false)
diff --git a/go/vt/vtgate/planbuilder/grouping.go b/go/vt/vtgate/planbuilder/grouping.go
index fec8ad38411..d81f3e52d25 100644
--- a/go/vt/vtgate/planbuilder/grouping.go
+++ b/go/vt/vtgate/planbuilder/grouping.go
@@ -20,6 +20,7 @@ import (
 	vtrpcpb "vitess.io/vitess/go/vt/proto/vtrpc"
 	"vitess.io/vitess/go/vt/sqlparser"
 	"vitess.io/vitess/go/vt/vterrors"
+	"vitess.io/vitess/go/vt/vtgate/engine"
 )
 
 func planGroupBy(pb *primitiveBuilder, input logicalPlan, groupBy sqlparser.GroupBy) (logicalPlan, error) {
@@ -76,7 +77,7 @@ func planGroupBy(pb *primitiveBuilder, input logicalPlan, groupBy sqlparser.Grou
 			default:
 				return nil, vterrors.New(vtrpcpb.Code_UNIMPLEMENTED, "unsupported: in scatter query: only simple references allowed")
 			}
-			node.eaggr.Keys = append(node.eaggr.Keys, colNumber)
+			node.eaggr.GroupByKeys = append(node.eaggr.GroupByKeys, engine.GroupbyParams{Col: colNumber, KeyCol: colNumber, WeightStringCol: -1})
 		}
 		// Append the distinct aggregate if any.
 		if node.extraDistinct != nil {
@@ -109,7 +110,7 @@ func planDistinct(input logicalPlan) (logicalPlan, error) {
 			if rc.column.Origin() == node {
 				return newDistinct(node), nil
 			}
-			node.eaggr.Keys = append(node.eaggr.Keys, i)
+			node.eaggr.GroupByKeys = append(node.eaggr.GroupByKeys, engine.GroupbyParams{Col: i, KeyCol: i, WeightStringCol: -1})
 		}
 		newInput, err := planDistinct(node.input)
 		if err != nil {
diff --git a/go/vt/vtgate/planbuilder/ordered_aggregate.go b/go/vt/vtgate/planbuilder/ordered_aggregate.go
index e3a82a08f47..60e5eea65a4 100644
--- a/go/vt/vtgate/planbuilder/ordered_aggregate.go
+++ b/go/vt/vtgate/planbuilder/ordered_aggregate.go
@@ -331,14 +331,15 @@ func (oa *orderedAggregate) needDistinctHandling(pb *primitiveBuilder, funcExpr
 // compare those instead. This is because we currently don't have the
 // ability to mimic mysql's collation behavior.
 func (oa *orderedAggregate) Wireup(plan logicalPlan, jt *jointab) error {
-	for i, colNumber := range oa.eaggr.Keys {
-		rc := oa.resultColumns[colNumber]
+	for i, gbk := range oa.eaggr.GroupByKeys {
+		rc := oa.resultColumns[gbk.Col]
 		if sqltypes.IsText(rc.column.typ) {
 			if weightcolNumber, ok := oa.weightStrings[rc]; ok {
-				oa.eaggr.Keys[i] = weightcolNumber
+				oa.eaggr.GroupByKeys[i].WeightStringCol = weightcolNumber
+				oa.eaggr.GroupByKeys[i].KeyCol = weightcolNumber
 				continue
 			}
-			weightcolNumber, err := oa.input.SupplyWeightString(colNumber)
+			weightcolNumber, err := oa.input.SupplyWeightString(gbk.Col)
 			if err != nil {
 				_, isUnsupportedErr := err.(UnsupportedSupplyWeightString)
 				if isUnsupportedErr {
@@ -347,7 +348,8 @@ func (oa *orderedAggregate) Wireup(plan logicalPlan, jt *jointab) error {
 				return err
 			}
 			oa.weightStrings[rc] = weightcolNumber
-			oa.eaggr.Keys[i] = weightcolNumber
+			oa.eaggr.GroupByKeys[i].WeightStringCol = weightcolNumber
+			oa.eaggr.GroupByKeys[i].KeyCol = weightcolNumber
 			oa.eaggr.TruncateColumnCount = len(oa.resultColumns)
 		}
 	}
diff --git a/go/vt/vtgate/planbuilder/ordering.go b/go/vt/vtgate/planbuilder/ordering.go
index d3d53f4d720..1a80d00b8b0 100644
--- a/go/vt/vtgate/planbuilder/ordering.go
+++ b/go/vt/vtgate/planbuilder/ordering.go
@@ -76,7 +76,7 @@ func planOAOrdering(pb *primitiveBuilder, orderBy sqlparser.OrderBy, oa *ordered
 	}
 
 	// referenced tracks the keys referenced by the order by clause.
-	referenced := make([]bool, len(oa.eaggr.Keys))
+	referenced := make([]bool, len(oa.eaggr.GroupByKeys))
 	postSort := false
 	selOrderBy := make(sqlparser.OrderBy, 0, len(orderBy))
 	for _, order := range orderBy {
@@ -103,8 +103,8 @@ func planOAOrdering(pb *primitiveBuilder, orderBy sqlparser.OrderBy, oa *ordered
 
 		// Match orderByCol against the group by columns.
 		found := false
-		for j, key := range oa.eaggr.Keys {
-			if oa.resultColumns[key].column != orderByCol {
+		for j, key := range oa.eaggr.GroupByKeys {
+			if oa.resultColumns[key.Col].column != orderByCol {
 				continue
 			}
 
@@ -119,12 +119,12 @@ func planOAOrdering(pb *primitiveBuilder, orderBy sqlparser.OrderBy, oa *ordered
 	}
 
 	// Append any unreferenced keys at the end of the order by.
-	for i, key := range oa.eaggr.Keys {
+	for i, key := range oa.eaggr.GroupByKeys {
 		if referenced[i] {
 			continue
 		}
 		// Build a brand new reference for the key.
-		col, err := BuildColName(oa.input.ResultColumns(), key)
+		col, err := BuildColName(oa.input.ResultColumns(), key.Col)
 		if err != nil {
 			return nil, vterrors.Wrapf(err, "generating order by clause")
 		}
diff --git a/go/vt/vtgate/planbuilder/selectGen4.go b/go/vt/vtgate/planbuilder/selectGen4.go
index 4edd6cf6d1c..6a519acf9c6 100644
--- a/go/vt/vtgate/planbuilder/selectGen4.go
+++ b/go/vt/vtgate/planbuilder/selectGen4.go
@@ -164,15 +164,11 @@ func planGroupByGen4(groupExpr abstract.GroupBy, plan logicalPlan, semTable *sem
 		sel.GroupBy = append(sel.GroupBy, groupExpr.Inner)
 		return false, nil
 	case *orderedAggregate:
-		offset, weightStringOffset, colAdded, err := funcName(groupExpr.Inner, groupExpr.WeightStrExpr, node.input, semTable)
+		offset, weightStringOffset, colAdded, err := wrapAndPushExpr(groupExpr.Inner, groupExpr.WeightStrExpr, node.input, semTable)
 		if err != nil {
 			return false, err
 		}
-		if weightStringOffset == -1 {
-			node.eaggr.Keys = append(node.eaggr.Keys, offset)
-		} else {
-			node.eaggr.Keys = append(node.eaggr.Keys, weightStringOffset)
-		}
+		node.eaggr.GroupByKeys = append(node.eaggr.GroupByKeys, engine.GroupbyParams{KeyCol: offset, Col: offset, WeightStringCol: weightStringOffset})
 		colAddedRecursively, err := planGroupByGen4(groupExpr, node.input, semTable)
 		if err != nil {
 			return false, err
@@ -228,7 +224,7 @@ func planOrderBy(qp *abstract.QueryProjection, orderExprs []abstract.OrderBy, pl
 func planOrderByForRoute(orderExprs []abstract.OrderBy, plan *route, semTable *semantics.SemTable) (logicalPlan, bool, error) {
 	origColCount := plan.Select.GetColumnCount()
 	for _, order := range orderExprs {
-		offset, weightStringOffset, _, err := funcName(order.Inner.Expr, order.WeightStrExpr, plan, semTable)
+		offset, weightStringOffset, _, err := wrapAndPushExpr(order.Inner.Expr, order.WeightStrExpr, plan, semTable)
 		if err != nil {
 			return nil, false, err
 		}
@@ -243,7 +239,7 @@ func planOrderByForRoute(orderExprs []abstract.OrderBy, plan *route, semTable *s
 	return plan, origColCount != plan.Select.GetColumnCount(), nil
 }
 
-func funcName(expr sqlparser.Expr, weightStrExpr sqlparser.Expr, plan logicalPlan, semTable *semantics.SemTable) (int, int, bool, error) {
+func wrapAndPushExpr(expr sqlparser.Expr, weightStrExpr sqlparser.Expr, plan logicalPlan, semTable *semantics.SemTable) (int, int, bool, error) {
 	offset, added, err := pushProjection(&sqlparser.AliasedExpr{Expr: expr}, plan, semTable, true, true)
 	if err != nil {
 		return 0, 0, false, err
@@ -314,7 +310,7 @@ func planOrderByForJoin(qp *abstract.QueryProjection, orderExprs []abstract.Orde
 
 	var colAdded bool
 	for _, order := range orderExprs {
-		offset, weightStringOffset, added, err := funcName(order.Inner.Expr, order.WeightStrExpr, plan, semTable)
+		offset, weightStringOffset, added, err := wrapAndPushExpr(order.Inner.Expr, order.WeightStrExpr, plan, semTable)
 		if err != nil {
 			return nil, false, err
 		}
diff --git a/go/vt/wrangler/vdiff.go b/go/vt/wrangler/vdiff.go
index 98dc89c3aeb..c4071eb6fee 100644
--- a/go/vt/wrangler/vdiff.go
+++ b/go/vt/wrangler/vdiff.go
@@ -529,15 +529,23 @@ func (df *vdiff) buildTablePlan(table *tabletmanagerdatapb.TableDefinition, quer
 	// the results, which engine.OrderedAggregate can do.
 	if len(aggregates) != 0 {
 		td.sourcePrimitive = &engine.OrderedAggregate{
-			Aggregates: aggregates,
-			Keys:       td.pkCols,
-			Input:      td.sourcePrimitive,
+			Aggregates:  aggregates,
+			GroupByKeys: pkColsToGroupByParams(td.pkCols),
+			Input:       td.sourcePrimitive,
 		}
 	}
 
 	return td, nil
 }
 
+func pkColsToGroupByParams(pkCols []int) []engine.GroupbyParams {
+	var res []engine.GroupbyParams
+	for _, col := range pkCols {
+		res = append(res, engine.GroupbyParams{Col: col, KeyCol: col, WeightStringCol: -1})
+	}
+	return res
+}
+
 // newMergeSorter creates an engine.MergeSort based on the shard streamers and pk columns.
 func newMergeSorter(participants map[string]*shardStreamer, comparePKs []compareColInfo) *engine.MergeSort {
 	prims := make([]engine.StreamExecutor, 0, len(participants))
diff --git a/go/vt/wrangler/vdiff_test.go b/go/vt/wrangler/vdiff_test.go
index 5d6e2b3ef46..c995d4b06e1 100644
--- a/go/vt/wrangler/vdiff_test.go
+++ b/go/vt/wrangler/vdiff_test.go
@@ -394,8 +394,8 @@ func TestVDiffPlanSuccess(t *testing.T) {
 					Opcode: engine.AggregateSum,
 					Col:    3,
 				}},
-				Keys:  []int{0},
-				Input: newMergeSorter(nil, []compareColInfo{{0, 0, true}}),
+				GroupByKeys: []engine.GroupbyParams{{Col: 0, KeyCol: 0, WeightStringCol: -1}},
+				Input:       newMergeSorter(nil, []compareColInfo{{0, 0, true}}),
 			},
 			targetPrimitive: newMergeSorter(nil, []compareColInfo{{0, 0, true}}),
 		},