diff --git a/pkg/sql/colexec/colexecjoin/mergejoiner.go b/pkg/sql/colexec/colexecjoin/mergejoiner.go
index 353a2afc4d9b..79e492b64df3 100644
--- a/pkg/sql/colexec/colexecjoin/mergejoiner.go
+++ b/pkg/sql/colexec/colexecjoin/mergejoiner.go
@@ -12,7 +12,6 @@ package colexecjoin
 
 import (
 	"context"
-	"math"
 	"unsafe"
 
 	"github.com/cockroachdb/cockroach/pkg/col/coldata"
@@ -92,9 +91,8 @@ type mjBufferedGroupState struct {
 	// rightFirstTuple is the first tuple of the right buffered group. It is set
 	//only in case the right buffered group spans more than one input batch.
 	rightFirstTuple []coldata.Vec
-	// rightScratchBatch is a scratch space for copying the tuples out of the
-	// right input batches before enqueueing them into the spilling queue.
-	rightScratchBatch coldata.Batch
+	// scratchSel is a scratch selection vector initialized only when needed.
+	scratchSel []int
 
 	// helper is the building facility for the cross join of the buffered group.
 	helper *crossJoinerBase
@@ -605,29 +603,56 @@ func (o *mergeJoinBase) appendToRightBufferedGroup(sel []int, groupStartIdx int,
 		return
 	}
 
-	// We don't impose any memory limits on the scratch batch because we rely on
-	// the inputs to the merge joiner to produce reasonably sized batches.
-	const maxBatchMemSize = math.MaxInt64
-	o.bufferedGroup.rightScratchBatch, _ = o.unlimitedAllocator.ResetMaybeReallocate(
-		sourceTypes, o.bufferedGroup.rightScratchBatch, groupLength, maxBatchMemSize,
-	)
-	// TODO(yuzefovich): SpillingQueue.Enqueue deep-copies the batch too. Think
-	// through whether the copy here can be avoided altogether.
-	o.unlimitedAllocator.PerformOperation(o.bufferedGroup.rightScratchBatch.ColVecs(), func() {
-		for colIdx := range sourceTypes {
-			o.bufferedGroup.rightScratchBatch.ColVec(colIdx).Copy(
-				coldata.SliceArgs{
-					Src:         o.proberState.rBatch.ColVec(colIdx),
-					Sel:         sel,
-					DestIdx:     0,
-					SrcStartIdx: groupStartIdx,
-					SrcEndIdx:   groupStartIdx + groupLength,
-				},
+	// Update the selection on the probing batch to only include tuples from the
+	// buffered group.
+	rBatch, rLength := o.proberState.rBatch, o.proberState.rLength
+	rSel := rBatch.Selection()
+	rBatchHasSel := rSel != nil
+	// No need to modify the batch if the whole batch is part of the buffered
+	// group.
+	needToModify := groupStartIdx != 0 || groupLength != rLength
+	if needToModify {
+		if rBatchHasSel {
+			// Since rBatch already has a selection vector which we'll be
+			// modifying, we need to copy the original.
+			o.bufferedGroup.scratchSel = colexecutils.EnsureSelectionVectorLength(o.bufferedGroup.scratchSel, rLength)
+			copy(o.bufferedGroup.scratchSel, rSel)
+			// Now we need to shift elements in range
+			// [groupStartIdx; groupStartIdx+groupLength) to the beginning of
+			// the selection vector and then update the length of the batch
+			// accordingly.
+			copy(rSel[:groupLength], rSel[groupStartIdx:groupStartIdx+groupLength])
+			rBatch.SetLength(groupLength)
+		} else {
+			// Since rBatch doesn't have a selection vector, we will set the
+			// selection vector to include tuples in range
+			// [groupStartIdx; groupStartIdx+groupLength).
+			colexecutils.UpdateBatchState(
+				rBatch, groupLength, true, /* usesSel */
+				defaultSelectionVector[groupStartIdx:groupStartIdx+groupLength],
 			)
 		}
-		o.bufferedGroup.rightScratchBatch.SetLength(groupLength)
-	})
-	bufferedTuples.Enqueue(o.Ctx, o.bufferedGroup.rightScratchBatch)
+	}
+
+	bufferedTuples.Enqueue(o.Ctx, rBatch)
+
+	// If we had to modify the batch, then restore the original state now.
+	if needToModify {
+		colexecutils.UpdateBatchState(
+			rBatch, rLength, rBatchHasSel, o.bufferedGroup.scratchSel,
+		)
+	}
+}
+
+// defaultSelectionVector contains all integers in [0, coldata.MaxBatchSize)
+// range.
+var defaultSelectionVector []int
+
+func init() {
+	defaultSelectionVector = make([]int, coldata.MaxBatchSize)
+	for i := range defaultSelectionVector {
+		defaultSelectionVector[i] = i
+	}
 }
 
 // sourceFinished returns true if either of input sources has no more rows.