diff --git a/dbms/src/Common/Exception.cpp b/dbms/src/Common/Exception.cpp
index 24e91b6c7a325269f3d9452b42b96c69f092d31f..3a50dc19ea49bf48101f70fa7a43c6f93c2fa938 100644
--- a/dbms/src/Common/Exception.cpp
+++ b/dbms/src/Common/Exception.cpp
@@ -259,7 +259,7 @@ std::string ExecutionStatus::serializeText() const
     std::string res;
     {
         WriteBufferFromString wb(res);
-        wb << code << "\n" << message;
+        wb << code << "\n" << escape << message;
     }
     return res;
 }
@@ -267,7 +267,7 @@ std::string ExecutionStatus::serializeText() const
 void ExecutionStatus::deserializeText(const std::string & data)
 {
     ReadBufferFromString rb(data);
-    rb >> code >> "\n" >> message;
+    rb >> code >> "\n" >> escape >> message;
 }
 
 ExecutionStatus ExecutionStatus::fromCurrentException(const std::string & start_of_message)
diff --git a/dbms/src/Common/Exception.h b/dbms/src/Common/Exception.h
index 7296b1640f724cc04426b0717611afc0517e4076..4465a407ddc8067a0ef3f71cac34691614b7681d 100644
--- a/dbms/src/Common/Exception.h
+++ b/dbms/src/Common/Exception.h
@@ -91,7 +91,7 @@ std::string getCurrentExceptionMessage(bool with_stacktrace, bool check_embedded
 int getCurrentExceptionCode();
 
 
-/// An execution status of any piece of code
+/// An execution status of any piece of code, contains return code and optional error
 struct ExecutionStatus
 {
     int code = 0;
diff --git a/dbms/src/Interpreters/DDLWorker.cpp b/dbms/src/Interpreters/DDLWorker.cpp
index 25a03ea9bfee51833614b7652c497fb4e915ec6c..ff44d19d13b53b77f5777d93fee768b276f5dff2 100644
--- a/dbms/src/Interpreters/DDLWorker.cpp
+++ b/dbms/src/Interpreters/DDLWorker.cpp
@@ -50,6 +50,10 @@ namespace ErrorCodes
 }
 
 
+const size_t DDLWorker::node_max_lifetime_seconds = 7 * 24 * 60 * 60; // week
+const size_t DDLWorker::cleanup_min_period_seconds = 60; // minute
+
+
 struct DDLLogEntry
 {
     String query;
@@ -65,7 +69,7 @@ struct DDLLogEntry
             WriteBufferFromString wb(res);
 
             wb << "version: " << CURRENT_VERSION << "\n";
-            wb << "query: " << query << "\n";
+            wb << "query: " << escape << query << "\n";
             wb << "hosts: " << hosts << "\n";
             wb << "initiator: " << initiator << "\n";
         }
@@ -83,7 +87,7 @@ struct DDLLogEntry
         if (version != CURRENT_VERSION)
             throw Exception("Unknown DDLLogEntry format version: " + version, ErrorCodes::UNKNOWN_FORMAT_VERSION);
 
-        rb >> "query: " >> query >> "\n";
+        rb >> "query: " >> escape >> query >> "\n";
         rb >> "hosts: " >> hosts >> "\n";
 
         if (!rb.eof())
@@ -128,7 +132,7 @@ static bool isSupportedAlterType(int type)
 
 
 DDLWorker::DDLWorker(const std::string & zk_root_dir, Context & context_)
-    : context(context_), stop_flag(false)
+    : context(context_)
 {
     queue_dir = zk_root_dir;
     if (queue_dir.back() == '/')
@@ -169,7 +173,9 @@ void DDLWorker::processTasks()
 
     for (auto it = begin_node; it != queue_nodes.end(); ++it)
     {
-        String node_data, node_name = *it, node_path = queue_dir + "/" + node_name;
+        const String & node_name = *it;
+        String node_path = queue_dir + "/" + node_name;
+        String node_data;
 
         if (!zookeeper->tryGet(node_path, node_data))
         {
diff --git a/dbms/src/Interpreters/DDLWorker.h b/dbms/src/Interpreters/DDLWorker.h
index fa232daa0eb9121de9b29ea2aa45d6768081f363..d2fe5edbdd75895967f70ac6b6f9708c4eebd00c 100644
--- a/dbms/src/Interpreters/DDLWorker.h
+++ b/dbms/src/Interpreters/DDLWorker.h
@@ -65,7 +65,7 @@ private:
     std::string queue_dir;      /// dir with queue of queries
     std::string master_dir;     /// dir with queries was initiated by the server
 
-    /// Used to omit already processed nodes;
+    /// Used to omit already processed nodes. Maybe usage of set is more obvious.
     std::string last_processed_node_name;
 
     std::shared_ptr<zkutil::ZooKeeper> zookeeper;
@@ -76,12 +76,15 @@ private:
     ExecutionStatus current_node_execution_status;
 
     std::shared_ptr<Poco::Event> event_queue_updated;
-    std::atomic<bool> stop_flag;
+    std::atomic<bool> stop_flag{false};
     std::thread thread;
 
     size_t last_cleanup_time_seconds = 0;
-    static constexpr size_t node_max_lifetime_seconds = 60; // 7 * 24 * 60 * 60;
-    static constexpr size_t cleanup_min_period_seconds = 60;
+
+    /// Delete node if its age is greater than that
+    static const size_t node_max_lifetime_seconds;
+    /// Cleaning starts after new node event is received if the last cleaning wasn't made sooner than N seconds ago
+    static const size_t cleanup_min_period_seconds;
 
     friend class DDLQueryStatusInputSream;
 };
diff --git a/dbms/src/Parsers/IAST.h b/dbms/src/Parsers/IAST.h
index 5b3ee192a32734149d2aca8b94e322103ce5b780..0cc861e6571aed07e62f50ad2e1df83d1df599e9 100644
--- a/dbms/src/Parsers/IAST.h
+++ b/dbms/src/Parsers/IAST.h
@@ -177,11 +177,7 @@ private:
 };
 
 
-<<<<<<< HEAD
-/// Quota the identifier with backquotes, if required.
-=======
 /// Surrounds an identifier by back quotes if it is necessary.
->>>>>>> Parsers refactoring. [#CLICKHOUSE-5]
 String backQuoteIfNeed(const String & x);