feat: update table options (#123)

diff --git a/protos/engine/manifest.proto b/protos/engine/manifest.proto
index afd9ab2..7429316 100644
--- a/protos/engine/manifest.proto
+++ b/protos/engine/manifest.proto
@@ -117,6 +117,7 @@
   // is still unknown.
   bool sampling_segment_duration = 11;
   StorageFormatHint storage_format_hint = 12;
+  LayeredMemtableOptions layered_memtable_options = 13;
 }
 
 enum UpdateMode {
@@ -171,3 +172,8 @@
   SNAPPY = 2;
   ZSTD = 3;
 }
+
+message LayeredMemtableOptions {
+  // Layered memtable will be disable when threshold is 0.
+  uint64 mutable_segment_switch_threshold = 1;
+}