From ab9a7be45ad647e7be832a61f31f03ae90ff9a40 Mon Sep 17 00:00:00 2001
From: alexey-milovidov <milovidov@yandex-team.ru>
Date: Sun, 22 Sep 2019 05:09:40 +0300
Subject: [PATCH] Comments are the must.

---
 dbms/src/Dictionaries/HashedDictionary.h | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/dbms/src/Dictionaries/HashedDictionary.h b/dbms/src/Dictionaries/HashedDictionary.h
index 5cd31ba3e80..fac7bddbb6e 100644
--- a/dbms/src/Dictionaries/HashedDictionary.h
+++ b/dbms/src/Dictionaries/HashedDictionary.h
@@ -13,6 +13,10 @@
 #include "IDictionary.h"
 #include "IDictionarySource.h"
 
+/** This dictionary stores all content in a hash table in memory
+  * (a separate Key -> Value map for each attribute)
+  * Two variants of hash table is supported: a fast HashMap and memory efficient sparse_hash_map.
+  */
 
 namespace DB
 {