From 4ebde2ac7e1951f97f685bdbc36466ab5d7a0786 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=D0=9F=D0=B0=D0=B2=D0=B5=D0=BB=20=D0=9B=D0=B8=D1=82=D0=B2?=
 =?UTF-8?q?=D0=B8=D0=BD=D0=B5=D0=BD=D0=BA=D0=BE?= <digitaldistortion@ya.ru>
Date: Sun, 4 Feb 2018 17:00:43 +0300
Subject: [PATCH] allow nulls in string field

---
 dbms/src/Dictionaries/MongoDBBlockInputStream.cpp | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/dbms/src/Dictionaries/MongoDBBlockInputStream.cpp b/dbms/src/Dictionaries/MongoDBBlockInputStream.cpp
index 162e3c14f18..3b822a5ed2e 100644
--- a/dbms/src/Dictionaries/MongoDBBlockInputStream.cpp
+++ b/dbms/src/Dictionaries/MongoDBBlockInputStream.cpp
@@ -105,6 +105,11 @@ namespace
                     static_cast<ColumnString &>(column).insertDataWithTerminatingZero(string_id.data(), string_id.size() + 1);
                     break;
                 }
+                else if (value.type() == Poco::MongoDB::ElementTraits<Poco::MongoDB::NullValue>::TypeId)
+                {
+                    static_cast<ColumnVector<String> &>(column).getData().emplace_back();
+                    break;
+                }
                 else if (value.type() == Poco::MongoDB::ElementTraits<String>::TypeId)
                 {
                     String string = static_cast<const Poco::MongoDB::ConcreteElement<String> &>(value).value();