diff --git a/runtime/vam/expr/agg/avg.go b/runtime/vam/expr/agg/avg.go
index 214215f776..7c17bd589f 100644
--- a/runtime/vam/expr/agg/avg.go
+++ b/runtime/vam/expr/agg/avg.go
@@ -43,13 +43,15 @@ func (a *avg) ConsumeAsPartial(partial vector.Any) {
 	if !ok1 || !ok2 {
 		panic("avg: invalid partial")
 	}
-	sumVal, ok1 := rec.Fields[si].(*vector.Const)
-	countVal, ok2 := rec.Fields[ci].(*vector.Const)
-	if !ok1 || !ok2 || sumVal.Type() != super.TypeFloat64 || countVal.Type() != super.TypeUint64 {
+	sumVal := rec.Fields[si]
+	countVal := rec.Fields[ci]
+	if sumVal.Type() != super.TypeFloat64 || countVal.Type() != super.TypeUint64 {
 		panic("avg: invalid partial")
 	}
-	a.sum += sumVal.Value().Float()
-	a.count += countVal.Value().Uint()
+	sum, _ := vector.FloatValue(sumVal, 0)
+	count, _ := vector.UintValue(countVal, 0)
+	a.sum += sum
+	a.count += count
 }
 
 func (a *avg) ResultAsPartial(zctx *super.Context) super.Value {
diff --git a/runtime/vam/expr/agg/count.go b/runtime/vam/expr/agg/count.go
index 9272efabc7..d25f9d4fbb 100644
--- a/runtime/vam/expr/agg/count.go
+++ b/runtime/vam/expr/agg/count.go
@@ -37,11 +37,11 @@ func (a *count) Result(*super.Context) super.Value {
 }
 
 func (a *count) ConsumeAsPartial(partial vector.Any) {
-	c, ok := partial.(*vector.Const)
-	if !ok || c.Len() != 1 || partial.Type() != super.TypeUint64 {
+	if partial.Len() != 1 || partial.Type() != super.TypeUint64 {
 		panic("count: bad partial")
 	}
-	a.count += c.Value().Uint()
+	count, _ := vector.UintValue(partial, 0)
+	a.count += count
 }
 
 func (a *count) ResultAsPartial(*super.Context) super.Value {
diff --git a/runtime/vam/op/summarize/agg.go b/runtime/vam/op/summarize/agg.go
index a3fa2a2b20..f592e72dae 100644
--- a/runtime/vam/op/summarize/agg.go
+++ b/runtime/vam/op/summarize/agg.go
@@ -24,7 +24,8 @@ type superTable struct {
 	builder     *vector.RecordBuilder
 	partialsIn  bool
 	partialsOut bool
-	table       map[string]aggRow
+	table       map[string]int
+	rows        []aggRow
 	zctx        *super.Context
 }
 
@@ -52,11 +53,13 @@ func (s *superTable) update(keys []vector.Any, args []vector.Any) {
 		m[string(keyBytes)] = append(m[string(keyBytes)], slot)
 	}
 	for rowKey, index := range m {
-		row, ok := s.table[rowKey]
+		id, ok := s.table[rowKey]
 		if !ok {
-			row = s.newRow(keys, index)
-			s.table[rowKey] = row
+			id = len(s.rows)
+			s.table[rowKey] = id
+			s.rows = append(s.rows, s.newRow(keys, index))
 		}
+		row := s.rows[id]
 		for i, arg := range args {
 			if len(m) > 1 {
 				arg = vector.NewView(arg, index)
@@ -85,32 +88,40 @@ func (s *superTable) newRow(keys []vector.Any, index []uint32) aggRow {
 }
 
 func (s *superTable) materialize() vector.Any {
+	if len(s.rows) == 0 {
+		return vector.NewConst(super.Null, 0, nil)
+	}
 	var vecs []vector.Any
-	var tags []uint32
-	// XXX This should reasonably concat all materialize rows together instead
-	// of this crazy Dynamic hack.
-	for _, row := range s.table {
-		tags = append(tags, uint32(len(tags)))
-		vecs = append(vecs, s.materializeRow(row))
+	for i := range s.rows[0].keys {
+		vecs = append(vecs, s.materializeKey(i))
+	}
+	for i := range s.rows[0].funcs {
+		vecs = append(vecs, s.materializeAgg(i))
 	}
-	return vector.NewDynamic(tags, vecs)
+	// Since aggs can return dynamic values need to do apply to create record.
+	return vector.Apply(false, func(vecs ...vector.Any) vector.Any {
+		return s.builder.New(vecs)
+	}, vecs...)
 }
 
-func (s *superTable) materializeRow(row aggRow) vector.Any {
-	var vecs []vector.Any
-	for _, key := range row.keys {
-		vecs = append(vecs, vector.NewConst(key, 1, nil))
+func (s *superTable) materializeKey(i int) vector.Any {
+	b := vector.NewBuilder(s.rows[0].keys[i].Type())
+	for _, row := range s.rows {
+		b.Write(row.keys[i].Bytes())
 	}
-	for _, fn := range row.funcs {
-		var val super.Value
+	return b.Build()
+}
+
+func (s *superTable) materializeAgg(i int) vector.Any {
+	b := vector.NewDynamicBuilder()
+	for _, row := range s.rows {
 		if s.partialsOut {
-			val = fn.ResultAsPartial(s.zctx)
+			b.Write(row.funcs[i].ResultAsPartial(s.zctx))
 		} else {
-			val = fn.Result(s.zctx)
+			b.Write(row.funcs[i].Result(s.zctx))
 		}
-		vecs = append(vecs, vector.NewConst(val, 1, nil))
 	}
-	return s.builder.New(vecs)
+	return b.Build()
 }
 
 type countByString struct {
diff --git a/runtime/vam/op/summarize/summarize.go b/runtime/vam/op/summarize/summarize.go
index 62d3d42204..0f85009da9 100644
--- a/runtime/vam/op/summarize/summarize.go
+++ b/runtime/vam/op/summarize/summarize.go
@@ -111,7 +111,7 @@ func (s *Summarize) newAggTable(keyTypes []super.Type) aggTable {
 		builder:     s.builder,
 		partialsIn:  s.partialsIn,
 		partialsOut: s.partialsOut,
-		table:       make(map[string]aggRow),
+		table:       make(map[string]int),
 		zctx:        s.zctx,
 	}
 }
diff --git a/vector/builder.go b/vector/builder.go
index a65c2f9d50..a9b7847937 100644
--- a/vector/builder.go
+++ b/vector/builder.go
@@ -14,6 +14,41 @@ type Builder interface {
 	Build() Any
 }
 
+type DynamicBuilder struct {
+	tags   []uint32
+	values []Builder
+	which  map[super.Type]int
+}
+
+func NewDynamicBuilder() *DynamicBuilder {
+	return &DynamicBuilder{
+		which: make(map[super.Type]int),
+	}
+}
+
+func (d *DynamicBuilder) Write(val super.Value) {
+	typ := val.Type()
+	tag, ok := d.which[typ]
+	if !ok {
+		tag = len(d.values)
+		d.values = append(d.values, NewBuilder(typ))
+		d.which[typ] = tag
+	}
+	d.tags = append(d.tags, uint32(tag))
+	d.values[tag].Write(val.Bytes())
+}
+
+func (d *DynamicBuilder) Build() Any {
+	var vecs []Any
+	for _, b := range d.values {
+		vecs = append(vecs, b.Build())
+	}
+	if len(vecs) == 1 {
+		return vecs[0]
+	}
+	return NewDynamic(d.tags, vecs)
+}
+
 func NewBuilder(typ super.Type) Builder {
 	var b Builder
 	switch typ := typ.(type) {