diff --git a/src/Interpreters/MetricLog.cpp b/src/Interpreters/MetricLog.cpp
index 96fe55c26e6..437d91e3743 100644
--- a/src/Interpreters/MetricLog.cpp
+++ b/src/Interpreters/MetricLog.cpp
@@ -35,10 +35,8 @@ Block MetricLogElement::createBlock()
 }
 
 
-void MetricLogElement::appendToBlock(Block & block) const
+void MetricLogElement::appendToBlock(MutableColumns & columns) const
 {
-    MutableColumns columns = block.mutateColumns();
-
     size_t column_idx = 0;
 
     columns[column_idx++]->insert(DateLUT::instance().toDayNum(event_time));
@@ -50,8 +48,6 @@ void MetricLogElement::appendToBlock(Block & block) const
 
     for (size_t i = 0, end = CurrentMetrics::end(); i < end; ++i)
         columns[column_idx++]->insert(current_metrics[i]);
-
-    block.setColumns(std::move(columns));
 }
 
 
diff --git a/src/Interpreters/MetricLog.h b/src/Interpreters/MetricLog.h
index a90ce923494..7774a45d7e1 100644
--- a/src/Interpreters/MetricLog.h
+++ b/src/Interpreters/MetricLog.h
@@ -25,7 +25,7 @@ struct MetricLogElement
 
     static std::string name() { return "MetricLog"; }
     static Block createBlock();
-    void appendToBlock(Block & block) const;
+    void appendToBlock(MutableColumns & columns) const;
 };
 
 
diff --git a/src/Interpreters/PartLog.cpp b/src/Interpreters/PartLog.cpp
index ab22e73a0ca..cc3a4e3de34 100644
--- a/src/Interpreters/PartLog.cpp
+++ b/src/Interpreters/PartLog.cpp
@@ -59,10 +59,8 @@ Block PartLogElement::createBlock()
     };
 }
 
-void PartLogElement::appendToBlock(Block & block) const
+void PartLogElement::appendToBlock(MutableColumns & columns) const
 {
-    MutableColumns columns = block.mutateColumns();
-
     size_t i = 0;
 
     columns[i++]->insert(event_type);
@@ -93,8 +91,6 @@ void PartLogElement::appendToBlock(Block & block) const
 
     columns[i++]->insert(error);
     columns[i++]->insert(exception);
-
-    block.setColumns(std::move(columns));
 }
 
 
diff --git a/src/Interpreters/PartLog.h b/src/Interpreters/PartLog.h
index b84138159a2..9c8bf414099 100644
--- a/src/Interpreters/PartLog.h
+++ b/src/Interpreters/PartLog.h
@@ -50,7 +50,7 @@ struct PartLogElement
     static std::string name() { return "PartLog"; }
 
     static Block createBlock();
-    void appendToBlock(Block & block) const;
+    void appendToBlock(MutableColumns & columns) const;
 };
 
 class IMergeTreeDataPart;
diff --git a/src/Interpreters/QueryLog.cpp b/src/Interpreters/QueryLog.cpp
index 1b104fe1a6c..007a118b4ce 100644
--- a/src/Interpreters/QueryLog.cpp
+++ b/src/Interpreters/QueryLog.cpp
@@ -85,10 +85,8 @@ Block QueryLogElement::createBlock()
 }
 
 
-void QueryLogElement::appendToBlock(Block & block) const
+void QueryLogElement::appendToBlock(MutableColumns & columns) const
 {
-    MutableColumns columns = block.mutateColumns();
-
     size_t i = 0;
 
     columns[i++]->insert(type);
@@ -146,8 +144,6 @@ void QueryLogElement::appendToBlock(Block & block) const
         columns[i++]->insertDefault();
         columns[i++]->insertDefault();
     }
-
-    block.setColumns(std::move(columns));
 }
 
 void QueryLogElement::appendClientInfo(const ClientInfo & client_info, MutableColumns & columns, size_t & i)
diff --git a/src/Interpreters/QueryLog.h b/src/Interpreters/QueryLog.h
index e503b417638..cbbe0156184 100644
--- a/src/Interpreters/QueryLog.h
+++ b/src/Interpreters/QueryLog.h
@@ -63,7 +63,7 @@ struct QueryLogElement
     static std::string name() { return "QueryLog"; }
 
     static Block createBlock();
-    void appendToBlock(Block & block) const;
+    void appendToBlock(MutableColumns & columns) const;
 
     static void appendClientInfo(const ClientInfo & client_info, MutableColumns & columns, size_t & i);
 };
diff --git a/src/Interpreters/QueryThreadLog.cpp b/src/Interpreters/QueryThreadLog.cpp
index f539a720449..97d35659d48 100644
--- a/src/Interpreters/QueryThreadLog.cpp
+++ b/src/Interpreters/QueryThreadLog.cpp
@@ -67,10 +67,8 @@ Block QueryThreadLogElement::createBlock()
     };
 }
 
-void QueryThreadLogElement::appendToBlock(Block & block) const
+void QueryThreadLogElement::appendToBlock(MutableColumns & columns) const
 {
-    MutableColumns columns = block.mutateColumns();
-
     size_t i = 0;
 
     columns[i++]->insert(DateLUT::instance().toDayNum(event_time));
@@ -107,8 +105,6 @@ void QueryThreadLogElement::appendToBlock(Block & block) const
         columns[i++]->insertDefault();
         columns[i++]->insertDefault();
     }
-
-    block.setColumns(std::move(columns));
 }
 
 }
diff --git a/src/Interpreters/QueryThreadLog.h b/src/Interpreters/QueryThreadLog.h
index e2c082eb54c..b43a3a49c95 100644
--- a/src/Interpreters/QueryThreadLog.h
+++ b/src/Interpreters/QueryThreadLog.h
@@ -44,7 +44,7 @@ struct QueryThreadLogElement
     static std::string name() { return "QueryThreadLog"; }
 
     static Block createBlock();
-    void appendToBlock(Block & block) const;
+    void appendToBlock(MutableColumns & columns) const;
 };
 
 
diff --git a/src/Interpreters/SystemLog.h b/src/Interpreters/SystemLog.h
index 218555bebbc..b49fef53eff 100644
--- a/src/Interpreters/SystemLog.h
+++ b/src/Interpreters/SystemLog.h
@@ -51,7 +51,7 @@ namespace DB
 
         static std::string name();
         static Block createBlock();
-        void appendToBlock(Block & block) const;
+        void appendToBlock(MutableColumns & columns) const;
     };
     */
 
@@ -345,9 +345,8 @@ void SystemLog<LogElement>::savingThreadFunction()
             uint64_t to_flush_end = 0;
 
             {
-                LOG_TRACE(log, "Sleeping");
                 std::unique_lock lock(mutex);
-                const bool predicate = flush_event.wait_for(lock,
+                flush_event.wait_for(lock,
                     std::chrono::milliseconds(flush_interval_milliseconds),
                     [&] ()
                     {
@@ -364,13 +363,6 @@ void SystemLog<LogElement>::savingThreadFunction()
                 queue.swap(to_flush);
 
                 exit_this_thread = is_shutdown;
-
-                LOG_TRACE(log, "Woke up"
-                    << (predicate ? " by condition" : " by timeout ("
-                            + toString(flush_interval_milliseconds) + " ms)")
-                    << ", " << to_flush.size() << " elements to flush"
-                    << " up to " << to_flush_end
-                    << (is_shutdown ? ", shutdown requested" : ""));
             }
 
             if (to_flush.empty())
@@ -404,8 +396,10 @@ void SystemLog<LogElement>::flushImpl(const std::vector<LogElement> & to_flush,
         prepareTable();
 
         Block block = LogElement::createBlock();
+        MutableColumns columns = block.mutateColumns();
         for (const auto & elem : to_flush)
-            elem.appendToBlock(block);
+            elem.appendToBlock(columns);
+        block.setColumns(std::move(columns));
 
         /// We write to table indirectly, using InterpreterInsertQuery.
         /// This is needed to support DEFAULT-columns in table.
diff --git a/src/Interpreters/TextLog.cpp b/src/Interpreters/TextLog.cpp
index 35e027616f6..d166b24ef4f 100644
--- a/src/Interpreters/TextLog.cpp
+++ b/src/Interpreters/TextLog.cpp
@@ -46,10 +46,8 @@ Block TextLogElement::createBlock()
     };
 }
 
-void TextLogElement::appendToBlock(Block & block) const
+void TextLogElement::appendToBlock(MutableColumns & columns) const
 {
-    MutableColumns columns = block.mutateColumns();
-
     size_t i = 0;
 
     columns[i++]->insert(DateLUT::instance().toDayNum(event_time));
@@ -68,8 +66,6 @@ void TextLogElement::appendToBlock(Block & block) const
 
     columns[i++]->insert(source_file);
     columns[i++]->insert(source_line);
-
-    block.setColumns(std::move(columns));
 }
 
 TextLog::TextLog(Context & context_, const String & database_name_,
diff --git a/src/Interpreters/TextLog.h b/src/Interpreters/TextLog.h
index 73c38429662..d5d1610dfb5 100644
--- a/src/Interpreters/TextLog.h
+++ b/src/Interpreters/TextLog.h
@@ -25,7 +25,7 @@ struct TextLogElement
 
     static std::string name() { return "TextLog"; }
     static Block createBlock();
-    void appendToBlock(Block & block) const;
+    void appendToBlock(MutableColumns & columns) const;
 };
 
 class TextLog : public SystemLog<TextLogElement>
diff --git a/src/Interpreters/TraceLog.cpp b/src/Interpreters/TraceLog.cpp
index 2367cc56ac0..3df182a61ca 100644
--- a/src/Interpreters/TraceLog.cpp
+++ b/src/Interpreters/TraceLog.cpp
@@ -35,10 +35,8 @@ Block TraceLogElement::createBlock()
     };
 }
 
-void TraceLogElement::appendToBlock(Block & block) const
+void TraceLogElement::appendToBlock(MutableColumns & columns) const
 {
-    MutableColumns columns = block.mutateColumns();
-
     size_t i = 0;
 
     columns[i++]->insert(DateLUT::instance().toDayNum(event_time));
@@ -50,6 +48,4 @@ void TraceLogElement::appendToBlock(Block & block) const
     columns[i++]->insertData(query_id.data(), query_id.size());
     columns[i++]->insert(trace);
     columns[i++]->insert(size);
-
-    block.setColumns(std::move(columns));
 }
diff --git a/src/Interpreters/TraceLog.h b/src/Interpreters/TraceLog.h
index c882ae69420..f97cdaaec40 100644
--- a/src/Interpreters/TraceLog.h
+++ b/src/Interpreters/TraceLog.h
@@ -24,7 +24,7 @@ struct TraceLogElement
 
     static std::string name() { return "TraceLog"; }
     static Block createBlock();
-    void appendToBlock(Block & block) const;
+    void appendToBlock(MutableColumns & columns) const;
 };
 
 class TraceLog : public SystemLog<TraceLogElement>