update table options.
diff --git a/protos/engine/manifest.proto b/protos/engine/manifest.proto
index fe9c0f2..a41d5cd 100644
--- a/protos/engine/manifest.proto
+++ b/protos/engine/manifest.proto
@@ -134,6 +134,8 @@
   // is still unknown.
   bool sampling_segment_duration = 11;
   StorageFormatHint storage_format_hint = 12;
+  MemtableType memtable_type = 13;
+  LayeredMemtableOptions layered_memtable_options = 14;
 }
 
 enum UpdateMode {
@@ -188,3 +190,12 @@
   SNAPPY = 2;
   ZSTD = 3;
 }
+
+enum MemtableType {
+  SkipList = 0;
+  Column = 1;
+}
+
+message LayeredMemtableOptions {
+  uint64 mutable_segment_switch_threshold = 1;
+}