diff --git a/internal/e2e/transaction_cases_test.go b/internal/e2e/transaction_cases_test.go
index 9f925a902..08cebd458 100644
--- a/internal/e2e/transaction_cases_test.go
+++ b/internal/e2e/transaction_cases_test.go
@@ -62,6 +62,25 @@ func runTransactionCases(c transactClient, m *namespaceTestManager) func(*testin
 			assert.Len(t, resp.RelationTuples, 0)
 		})
 
+		t.Run("case=duplicate string representations", func(t *testing.T) {
+			n := &namespace.Namespace{Name: t.Name()}
+			m.add(t, n)
+			c.transactTuples(t, []*ketoapi.RelationTuple{
+				{
+					Namespace: n.Name,
+					Object:    "o",
+					Relation:  "rel",
+					SubjectID: pointerx.Ptr("sid"),
+				},
+				{
+					Namespace: n.Name,
+					Object:    "o",
+					Relation:  "rel",
+					SubjectID: pointerx.Ptr("sid"),
+				},
+			}, nil)
+		})
+
 		t.Run("case=large inserts and deletes", func(t *testing.T) {
 			if !testing.Short() {
 				t.Skip("This test is fairly expensive, especially the deletion.")
diff --git a/internal/persistence/sql/relationtuples.go b/internal/persistence/sql/relationtuples.go
index b6f40f781..4daf6ecfc 100644
--- a/internal/persistence/sql/relationtuples.go
+++ b/internal/persistence/sql/relationtuples.go
@@ -175,14 +175,14 @@ func buildDelete(nid uuid.UUID, rs []*relationtuple.RelationTuple) (query string
 }
 
 func (p *Persister) DeleteRelationTuples(ctx context.Context, rs ...*relationtuple.RelationTuple) (err error) {
-	ctx, span := p.d.Tracer(ctx).Tracer().Start(ctx, "persistence.sql.DeleteRelationTuples",
-		trace.WithAttributes(attribute.Int("count", len(rs))))
-	defer otelx.End(span, &err)
-
 	if len(rs) == 0 {
 		return nil
 	}
 
+	ctx, span := p.d.Tracer(ctx).Tracer().Start(ctx, "persistence.sql.DeleteRelationTuples",
+		trace.WithAttributes(attribute.Int("count", len(rs))))
+	defer otelx.End(span, &err)
+
 	return p.Transaction(ctx, func(ctx context.Context) error {
 		for chunk := range slices.Chunk(rs, chunkSizeDeleteTuple) {
 			q, args, err := buildDelete(p.NetworkID(ctx), chunk)
@@ -310,14 +310,14 @@ func buildInsert(commitTime time.Time, nid uuid.UUID, rs []*relationtuple.Relati
 }
 
 func (p *Persister) WriteRelationTuples(ctx context.Context, rs ...*relationtuple.RelationTuple) (err error) {
-	ctx, span := p.d.Tracer(ctx).Tracer().Start(ctx, "persistence.sql.WriteRelationTuples",
-		trace.WithAttributes(attribute.Int("count", len(rs))))
-	defer otelx.End(span, &err)
-
 	if len(rs) == 0 {
 		return nil
 	}
 
+	ctx, span := p.d.Tracer(ctx).Tracer().Start(ctx, "persistence.sql.WriteRelationTuples",
+		trace.WithAttributes(attribute.Int("count", len(rs))))
+	defer otelx.End(span, &err)
+
 	commitTime := time.Now()
 
 	return p.Transaction(ctx, func(ctx context.Context) error {
diff --git a/internal/persistence/sql/uuid_mapping.go b/internal/persistence/sql/uuid_mapping.go
index 4cd429a41..633b8db19 100644
--- a/internal/persistence/sql/uuid_mapping.go
+++ b/internal/persistence/sql/uuid_mapping.go
@@ -4,6 +4,7 @@
 package sql
 
 import (
+	"bytes"
 	"context"
 	"iter"
 	"maps"
@@ -13,6 +14,8 @@ import (
 	"github.com/gofrs/uuid"
 	"github.com/ory/x/otelx"
 	"github.com/ory/x/sqlcon"
+	"go.opentelemetry.io/otel/attribute"
+	"go.opentelemetry.io/otel/trace"
 
 	"github.com/ory/keto/internal/x"
 )
@@ -89,13 +92,14 @@ func (p *Persister) batchFromUUIDs(ctx context.Context, ids []uuid.UUID, opts ..
 }
 
 func (p *Persister) MapStringsToUUIDs(ctx context.Context, values ...string) (uuids []uuid.UUID, err error) {
-	ctx, span := p.d.Tracer(ctx).Tracer().Start(ctx, "persistence.sql.MapStringsToUUIDs")
-	defer otelx.End(span, &err)
-
 	if len(values) == 0 {
 		return
 	}
 
+	ctx, span := p.d.Tracer(ctx).Tracer().Start(ctx, "persistence.sql.MapStringsToUUIDs",
+		trace.WithAttributes(attribute.Int("num_values", len(values))))
+	defer otelx.End(span, &err)
+
 	uuids, err = p.MapStringsToUUIDsReadOnly(ctx, values...)
 	if err != nil {
 		return nil, err
@@ -110,6 +114,14 @@ func (p *Persister) MapStringsToUUIDs(ctx context.Context, values ...string) (uu
 			StringRepresentation: values[i],
 		}
 	}
+	slices.SortFunc(mappings, func(a, b UUIDMapping) int {
+		return bytes.Compare(a.ID[:], b.ID[:])
+	})
+	mappings = slices.CompactFunc(mappings, func(a, b UUIDMapping) bool {
+		return a.ID == b.ID
+	})
+
+	span.SetAttributes(attribute.Int("num_mappings", len(mappings)))
 
 	err = p.Transaction(ctx, func(ctx context.Context) error {
 		for chunk := range slices.Chunk(mappings, chunkSizeInsertUUIDMappings) {