diff --git a/badger/count.go b/badger/count.go
index c2d79e2..3012437 100644
--- a/badger/count.go
+++ b/badger/count.go
@@ -10,7 +10,7 @@ import (
 	"github.com/nbd-wtf/go-nostr"
 )
 
-func (b BadgerBackend) CountEvents(ctx context.Context, filter nostr.Filter) (int64, error) {
+func (b *BadgerBackend) CountEvents(ctx context.Context, filter nostr.Filter) (int64, error) {
 	var count int64 = 0
 
 	queries, extraFilter, since, err := prepareQueries(filter)
diff --git a/badger/helpers.go b/badger/helpers.go
index b77f641..a5f0fef 100644
--- a/badger/helpers.go
+++ b/badger/helpers.go
@@ -43,7 +43,7 @@ func getTagIndexPrefix(tagValue string) ([]byte, int) {
 	return k, offset
 }
 
-func (b BadgerBackend) getIndexKeysForEvent(evt *nostr.Event, idx []byte) iter.Seq[[]byte] {
+func (b *BadgerBackend) getIndexKeysForEvent(evt *nostr.Event, idx []byte) iter.Seq[[]byte] {
 	return func(yield func([]byte) bool) {
 		{
 			// ~ by id
diff --git a/badger/query.go b/badger/query.go
index 8aa45b9..5fc2346 100644
--- a/badger/query.go
+++ b/badger/query.go
@@ -21,7 +21,7 @@ type iterEvent struct {
 
 var BatchFilled = errors.New("batch-filled")
 
-func (b BadgerBackend) QueryEvents(ctx context.Context, filter nostr.Filter) (chan *nostr.Event, error) {
+func (b *BadgerBackend) QueryEvents(ctx context.Context, filter nostr.Filter) (chan *nostr.Event, error) {
 	ch := make(chan *nostr.Event)
 
 	if filter.Search != "" {
diff --git a/badger/replace.go.bak b/badger/replace.go.bak
new file mode 100644
index 0000000..a5d3300
--- /dev/null
+++ b/badger/replace.go.bak
@@ -0,0 +1,68 @@
+package badger
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/nbd-wtf/go-nostr"
+)
+
+func (b *BadgerBackend) ReplaceEvent(ctx context.Context, matcher nostr.Filter, newEvent *nostr.Event) error {
+	if 20000 <= evt.Kind && evt.Kind < 30000 {
+		// do not store ephemeral events
+		return nil
+	} else if evt.Kind == 0 || evt.Kind == 3 || (10000 <= evt.Kind && evt.Kind < 20000) {
+		// replaceable event, delete before storing
+		ch, err := w.Store.QueryEvents(ctx, nostr.Filter{Authors: []string{evt.PubKey}, Kinds: []int{evt.Kind}})
+		if err != nil {
+			return fmt.Errorf("failed to query before replacing: %w", err)
+		}
+		isNewer := true
+		for previous := range ch {
+			if previous == nil {
+				continue
+			}
+			if isOlder(previous, &evt) {
+				if err := w.Store.DeleteEvent(ctx, previous); err != nil {
+					return fmt.Errorf("failed to delete event for replacing: %w", err)
+				}
+			} else {
+				// already, newer event is stored.
+				isNewer = false
+				break
+			}
+		}
+		if !isNewer {
+			return nil
+		}
+	} else if 30000 <= evt.Kind && evt.Kind < 40000 {
+		// parameterized replaceable event, delete before storing
+		d := evt.Tags.GetFirst([]string{"d", ""})
+		if d == nil {
+			return fmt.Errorf("failed to add event missing d tag for parameterized replacing")
+		}
+		ch, err := w.Store.QueryEvents(ctx, nostr.Filter{Authors: []string{evt.PubKey}, Kinds: []int{evt.Kind}, Tags: nostr.TagMap{"d": []string{d.Value()}}})
+		if err != nil {
+			return fmt.Errorf("failed to query before parameterized replacing: %w", err)
+		}
+		isNewer := true
+		for previous := range ch {
+			if previous == nil {
+				continue
+			}
+
+			if !isOlder(previous, &evt) {
+				if err := w.Store.DeleteEvent(ctx, previous); err != nil {
+					return fmt.Errorf("failed to delete event for parameterized replacing: %w", err)
+				}
+			} else {
+				// already, newer event is stored.
+				isNewer = false
+				break
+			}
+		}
+		if !isNewer {
+			return nil
+		}
+	}
+}