diff --git a/pebble.go b/pebble.go
index 946c23b..2321735 100644
--- a/pebble.go
+++ b/pebble.go
@@ -1,6 +1,3 @@
-//go:build pebbledb
-// +build pebbledb
-
 package db
 
 import (
@@ -32,6 +29,10 @@ func NewPebbleDB(name string, dir string) (*PebbleDB, error) {
 }
 
 func NewPebbleDBWithOpts(name string, dir string, opts *pebble.Options) (*PebbleDB, error) {
+	// configure pebble
+	opts.MemTableSize = 256 << 20           // 256 MB
+	opts.Cache = pebble.NewCache(256 << 20) // 256 MB
+	opts.LBaseMaxBytes = 64 << 20           // 64 MB
 	dbPath := filepath.Join(dir, name+".db")
 	opts.EnsureDefaults()
 	p, err := pebble.Open(dbPath, opts)
@@ -121,13 +122,13 @@ func (db *PebbleDB) Delete(key []byte) error {
 }
 
 // DeleteSync implements DB.
-func (db PebbleDB) DeleteSync(key []byte) error {
+func (db *PebbleDB) DeleteSync(key []byte) error {
 	if len(key) == 0 {
 		return errKeyEmpty
 	}
 	err := db.db.Delete(key, pebble.Sync)
 	if err != nil {
-		return nil
+		return err
 	}
 	return nil
 }
@@ -161,7 +162,7 @@ func (db *PebbleDB) Compact(start, end []byte) (err error) {
 		end = append(end, iter.Key()...)
 	}
 	err = db.db.Compact(start, end, true)
-	return
+	return err
 }
 
 // Close implements DB.
@@ -186,8 +187,27 @@ func (db *PebbleDB) Print() error {
 }
 
 // Stats implements DB.
-func (*PebbleDB) Stats() map[string]string {
-	return nil
+func (db *PebbleDB) Stats() map[string]string {
+	stats := make(map[string]string)
+	metrics := db.db.Metrics()
+
+	// Convert metrics to a map of strings
+	stats["BlockCacheSize"] = fmt.Sprintf("%d", metrics.BlockCache.Size)
+	stats["BlockCacheCount"] = fmt.Sprintf("%d", metrics.BlockCache.Count)
+	stats["BlockCacheHits"] = fmt.Sprintf("%d", metrics.BlockCache.Hits)
+	stats["BlockCacheMisses"] = fmt.Sprintf("%d", metrics.BlockCache.Misses)
+
+	stats["MemTableSize"] = fmt.Sprintf("%d", metrics.MemTable.Size)
+	stats["MemTableCount"] = fmt.Sprintf("%d", metrics.MemTable.Count)
+
+	stats["TableCacheSize"] = fmt.Sprintf("%d", metrics.TableCache.Size)
+	stats["TableCacheCount"] = fmt.Sprintf("%d", metrics.TableCache.Count)
+	stats["TableCacheHits"] = fmt.Sprintf("%d", metrics.TableCache.Hits)
+	stats["TableCacheMisses"] = fmt.Sprintf("%d", metrics.TableCache.Misses)
+
+	// Add more metrics as needed
+
+	return stats
 }
 
 // NewBatch implements DB.
@@ -352,6 +372,8 @@ func (itr *pebbleDBIterator) Domain() ([]byte, []byte) {
 	return itr.start, itr.end
 }
 
+// Valid implements Iterator.
+
 // Valid implements Iterator.
 func (itr *pebbleDBIterator) Valid() bool {
 	// Once invalid, forever invalid.
@@ -362,31 +384,25 @@ func (itr *pebbleDBIterator) Valid() bool {
 	// If source has error, invalid.
 	if err := itr.source.Error(); err != nil {
 		itr.isInvalid = true
-
 		return false
 	}
 
 	// If source is invalid, invalid.
 	if !itr.source.Valid() {
 		itr.isInvalid = true
-
 		return false
 	}
 
-	// If key is end or past it, invalid.
-	start := itr.start
-	end := itr.end
+	// If key is out of bounds, invalid.
 	key := itr.source.Key()
 	if itr.isReverse {
-		if start != nil && bytes.Compare(key, start) < 0 {
+		if itr.start != nil && bytes.Compare(key, itr.start) < 0 {
 			itr.isInvalid = true
-
 			return false
 		}
 	} else {
-		if end != nil && bytes.Compare(end, key) <= 0 {
+		if itr.end != nil && bytes.Compare(itr.end, key) <= 0 {
 			itr.isInvalid = true
-
 			return false
 		}
 	}
@@ -412,13 +428,22 @@ func (itr *pebbleDBIterator) Value() []byte {
 }
 
 // Next implements Iterator.
-func (itr pebbleDBIterator) Next() {
-	itr.assertIsValid()
+func (itr *pebbleDBIterator) Next() {
+	// Before moving the iterator, we need to check if it's valid.
+	if !itr.Valid() {
+		panic("iterator is invalid")
+	}
+
 	if itr.isReverse {
 		itr.source.Prev()
 	} else {
 		itr.source.Next()
 	}
+
+	// After moving the iterator, we need to check if it's still valid.
+	if !itr.source.Valid() {
+		itr.isInvalid = true
+	}
 }
 
 // Error implements Iterator.