Add missing DB functions to DocumentDB

utilities/document/document_db.cc

@@ -1000,6 +1000,10 @@ class DocumentDBImpl : public DocumentDB {
                      std::string* value) override {
     return Status::NotSupported("");
   }
+  virtual Status Get(const ReadOptions& options, const Slice& key,
+                     std::string* value) override {
+    return Status::NotSupported("");
+  }
   virtual Status Write(const WriteOptions& options,
                        WriteBatch* updates) override {
     return Status::NotSupported("");
@@ -1008,6 +1012,9 @@ class DocumentDBImpl : public DocumentDB {
                                 ColumnFamilyHandle* column_family) override {
     return nullptr;
   }
+  virtual Iterator* NewIterator(const ReadOptions& options) override {
+    return nullptr;
+  }
 
  private:
   Cursor* ConstructFilterCursor(ReadOptions read_options, Cursor* cursor,