refactor: remove dead code in cacheMergeIterator Domain() (cosmos#13433)

CHANGELOG.md

@@ -77,6 +77,7 @@ Ref: https://keepachangelog.com/en/1.0.0/
 * [#13168](https://github.com/cosmos/cosmos-sdk/pull/13168) Migrate tendermintdev/proto-builder to ghcr.io. New image `ghcr.io/cosmos/proto-builder:0.8`
 * [#13178](https://github.com/cosmos/cosmos-sdk/pull/13178) Add `cosmos.msg.v1.service` protobuf annotation to allow tooling to distinguish between Msg and Query services via reflection. 
 * [#13236](https://github.com/cosmos/cosmos-sdk/pull/13236) Integrate Filter Logging
+* [#13433](https://github.com/cosmos/cosmos-sdk/pull/13433) Remove dead code in cacheMergeIterator `Domain()`.
 
 ### State Machine Breaking
 

store/cachekv/memiterator.go

@@ -19,8 +19,10 @@ type memIterator struct {
 }
 
 func newMemIterator(start, end []byte, items *dbm.MemDB, deleted map[string]struct{}, ascending bool) *memIterator {
-	var iter types.Iterator
-	var err error
+	var (
+		iter types.Iterator
+		err  error
+	)
 
 	if ascending {
 		iter, err = items.Iterator(start, end)
@@ -34,9 +36,8 @@ func newMemIterator(start, end []byte, items *dbm.MemDB, deleted map[string]stru
 
 	return &memIterator{
 		Iterator: iter,
-
-		lastKey: nil,
-		deleted: deleted,
+		lastKey:  nil,
+		deleted:  deleted,
 	}
 }
 

store/cachekv/mergeiterator.go

@@ -33,24 +33,9 @@ func newCacheMergeIterator(parent, cache types.Iterator, ascending bool) *cacheM
 }
 
 // Domain implements Iterator.
-// If the domains are different, returns the union.
+// Returns parent domain because cache and parent domains are the same.
 func (iter *cacheMergeIterator) Domain() (start, end []byte) {
-	startP, endP := iter.parent.Domain()
-	startC, endC := iter.cache.Domain()
-
-	if iter.compare(startP, startC) < 0 {
-		start = startP
-	} else {
-		start = startC
-	}
-
-	if iter.compare(endP, endC) < 0 {
-		end = endC
-	} else {
-		end = endP
-	}
-
-	return start, end
+	return iter.parent.Domain()
 }
 
 // Valid implements Iterator.