diff --git a/dbms/CMakeLists.txt b/dbms/CMakeLists.txt
index 4bb59a8186d..93d85c720dc 100644
--- a/dbms/CMakeLists.txt
+++ b/dbms/CMakeLists.txt
@@ -18,6 +18,8 @@ get_property (BUILD_INCLUDE_DIRECTORIES DIRECTORY ${ClickHouse_SOURCE_DIR} PROPE
 string (TIMESTAMP BUILD_DATE "%Y-%m-%d" UTC)
 configure_file (${CMAKE_CURRENT_SOURCE_DIR}/src/Common/config_build.cpp.in ${CONFIG_BUILD})
 
+#set (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wextra")
+
 if (NOT NO_WERROR)
     set (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Werror")
     set (CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Werror")
diff --git a/dbms/src/Columns/ColumnFixedString.h b/dbms/src/Columns/ColumnFixedString.h
index d1aced191e6..962684bc9ee 100644
--- a/dbms/src/Columns/ColumnFixedString.h
+++ b/dbms/src/Columns/ColumnFixedString.h
@@ -99,7 +99,7 @@ public:
 
     void updateHashWithValue(size_t index, SipHash & hash) const override;
 
-    int compareAt(size_t p1, size_t p2, const IColumn & rhs_, int nan_direction_hint) const override
+    int compareAt(size_t p1, size_t p2, const IColumn & rhs_, int /*nan_direction_hint*/) const override
     {
         const ColumnFixedString & rhs = static_cast<const ColumnFixedString &>(rhs_);
         return memcmp(&chars[p1 * n], &rhs.chars[p2 * n], n);
diff --git a/dbms/src/Columns/ColumnVector.h b/dbms/src/Columns/ColumnVector.h
index b49c31b7319..a9fa02282e3 100644
--- a/dbms/src/Columns/ColumnVector.h
+++ b/dbms/src/Columns/ColumnVector.h
@@ -16,8 +16,8 @@ namespace DB
 template <typename T>
 struct CompareHelper
 {
-    static bool less(T a, T b, int nan_direction_hint) { return a < b; }
-    static bool greater(T a, T b, int nan_direction_hint) { return a > b; }
+    static bool less(T a, T b, int /*nan_direction_hint*/) { return a < b; }
+    static bool greater(T a, T b, int /*nan_direction_hint*/) { return a > b; }
 
     /** Compares two numbers. Returns a number less than zero, equal to zero, or greater than zero if a < b, a == b, a > b, respectively.
       * If one of the values is NaN, then
@@ -25,7 +25,7 @@ struct CompareHelper
       * - if nan_direction_hint == 1 - NaN are considered to be larger than all numbers;
       * Essentially: nan_direction_hint == -1 says that the comparison is for sorting in descending order.
       */
-    static int compare(T a, T b, int nan_direction_hint)
+    static int compare(T a, T b, int /*nan_direction_hint*/)
     {
         return a > b ? 1 : (a < b ? -1 : 0);
     }
@@ -156,7 +156,7 @@ public:
         data.push_back(static_cast<const Self &>(src).getData()[n]);
     }
 
-    void insertData(const char * pos, size_t length) override
+    void insertData(const char * pos, size_t /*length*/) override
     {
         data.push_back(*reinterpret_cast<const T *>(pos));
     }
diff --git a/dbms/src/Columns/IColumn.h b/dbms/src/Columns/IColumn.h
index ff27021e584..3cdb843fad0 100644
--- a/dbms/src/Columns/IColumn.h
+++ b/dbms/src/Columns/IColumn.h
@@ -77,7 +77,7 @@ public:
     /// Creates column with the same type and specified size.
     /// If size is less current size, then data is cut.
     /// If size is greater, than default values are appended.
-    virtual ColumnPtr cloneResized(size_t size) const { throw Exception("Cannot cloneResized() column " + getName(), ErrorCodes::NOT_IMPLEMENTED); }
+    virtual ColumnPtr cloneResized(size_t /*size*/) const { throw Exception("Cannot cloneResized() column " + getName(), ErrorCodes::NOT_IMPLEMENTED); }
 
     /// Returns number of values in column.
     virtual size_t size() const = 0;
@@ -106,7 +106,7 @@ public:
     /// If column stores integers, it returns n-th element transformed to UInt64 using static_cast.
     /// If column stores floting point numbers, bits of n-th elements are copied to lower bits of UInt64, the remaining bits are zeros.
     /// Is used to optimize some computations (in aggregation, for example).
-    virtual UInt64 get64(size_t n) const
+    virtual UInt64 get64(size_t /*n*/) const
     {
         throw Exception("Method get64 is not supported for " + getName(), ErrorCodes::NOT_IMPLEMENTED);
     }
@@ -114,12 +114,12 @@ public:
     /** If column is numeric, return value of n-th element, casted to UInt64.
       * Otherwise throw an exception.
       */
-    virtual UInt64 getUInt(size_t n) const
+    virtual UInt64 getUInt(size_t /*n*/) const
     {
         throw Exception("Method getUInt is not supported for " + getName(), ErrorCodes::NOT_IMPLEMENTED);
     }
 
-    virtual Int64 getInt(size_t n) const
+    virtual Int64 getInt(size_t /*n*/) const
     {
         throw Exception("Method getInt is not supported for " + getName(), ErrorCodes::NOT_IMPLEMENTED);
     }
@@ -253,7 +253,7 @@ public:
 
     /// Reserves memory for specified amount of elements. If reservation isn't possible, does nothing.
     /// It affects performance only (not correctness).
-    virtual void reserve(size_t n) {};
+    virtual void reserve(size_t /*n*/) {};
 
     /// Size of column data in memory (may be approximate) - for profiling. Zero, if could not be determined.
     virtual size_t byteSize() const = 0;
diff --git a/dbms/src/Common/AIO.h b/dbms/src/Common/AIO.h
index 1eeb787a376..e2f11ad3869 100644
--- a/dbms/src/Common/AIO.h
+++ b/dbms/src/Common/AIO.h
@@ -128,7 +128,7 @@ class AIOContextPool : public ext::singleton<AIOContextPool>
 
     int getCompletionEvents(io_event events[], const int max_events)
     {
-        timespec timeout{timeout_sec};
+        timespec timeout{timeout_sec, 0};
 
         auto num_events = 0;
 
diff --git a/dbms/src/Common/FieldVisitors.cpp b/dbms/src/Common/FieldVisitors.cpp
index d3b197936e0..4a20b1e7e2e 100644
--- a/dbms/src/Common/FieldVisitors.cpp
+++ b/dbms/src/Common/FieldVisitors.cpp
@@ -30,7 +30,7 @@ static inline String formatQuotedWithPrefix(T x, const char * prefix)
 }
 
 
-String FieldVisitorDump::operator() (const Null & x) const { return "NULL"; }
+String FieldVisitorDump::operator() (const Null &) const { return "NULL"; }
 String FieldVisitorDump::operator() (const UInt64 & x) const { return formatQuotedWithPrefix(x, "UInt64_"); }
 String FieldVisitorDump::operator() (const Int64 & x) const { return formatQuotedWithPrefix(x, "Int64_"); }
 String FieldVisitorDump::operator() (const Float64 & x) const { return formatQuotedWithPrefix(x, "Float64_"); }
@@ -99,7 +99,7 @@ static String formatFloat(const Float64 x)
 }
 
 
-String FieldVisitorToString::operator() (const Null & x) const { return "NULL"; }
+String FieldVisitorToString::operator() (const Null &) const { return "NULL"; }
 String FieldVisitorToString::operator() (const UInt64 & x) const { return formatQuoted(x); }
 String FieldVisitorToString::operator() (const Int64 & x) const { return formatQuoted(x); }
 String FieldVisitorToString::operator() (const Float64 & x) const { return formatFloat(x); }
@@ -142,7 +142,7 @@ String FieldVisitorToString::operator() (const Tuple & x_def) const
 
 FieldVisitorHash::FieldVisitorHash(SipHash & hash) : hash(hash) {}
 
-void FieldVisitorHash::operator() (const Null & x) const
+void FieldVisitorHash::operator() (const Null &) const
 {
     UInt8 type = Field::Types::Null;
     hash.update(reinterpret_cast<const char *>(&type), sizeof(type));
diff --git a/dbms/src/Common/FieldVisitors.h b/dbms/src/Common/FieldVisitors.h
index de53dc04a03..01b4e3353b2 100644
--- a/dbms/src/Common/FieldVisitors.h
+++ b/dbms/src/Common/FieldVisitors.h
@@ -133,22 +133,22 @@ template <typename T>
 class FieldVisitorConvertToNumber : public StaticVisitor<T>
 {
 public:
-    T operator() (const Null & x) const
+    T operator() (const Null &) const
     {
         throw Exception("Cannot convert NULL to " + String(TypeName<T>::get()), ErrorCodes::CANNOT_CONVERT_TYPE);
     }
 
-    T operator() (const String & x) const
+    T operator() (const String &) const
     {
         throw Exception("Cannot convert String to " + String(TypeName<T>::get()), ErrorCodes::CANNOT_CONVERT_TYPE);
     }
 
-    T operator() (const Array & x) const
+    T operator() (const Array &) const
     {
         throw Exception("Cannot convert Array to " + String(TypeName<T>::get()), ErrorCodes::CANNOT_CONVERT_TYPE);
     }
 
-    T operator() (const Tuple & x) const
+    T operator() (const Tuple &) const
     {
         throw Exception("Cannot convert Tuple to " + String(TypeName<T>::get()), ErrorCodes::CANNOT_CONVERT_TYPE);
     }
@@ -183,121 +183,121 @@ public:
 class FieldVisitorAccurateEquals : public StaticVisitor<bool>
 {
 public:
-    bool operator() (const Null & l, const Null & r)        const { return true; }
-    bool operator() (const Null & l, const UInt64 & r)      const { return false; }
-    bool operator() (const Null & l, const Int64 & r)       const { return false; }
-    bool operator() (const Null & l, const Float64 & r)     const { return false; }
-    bool operator() (const Null & l, const String & r)      const { return false; }
-    bool operator() (const Null & l, const Array & r)       const { return false; }
-    bool operator() (const Null & l, const Tuple & r)       const { return false; }
+    bool operator() (const Null &, const Null &)        const { return true; }
+    bool operator() (const Null &, const UInt64 &)      const { return false; }
+    bool operator() (const Null &, const Int64 &)       const { return false; }
+    bool operator() (const Null &, const Float64 &)     const { return false; }
+    bool operator() (const Null &, const String &)      const { return false; }
+    bool operator() (const Null &, const Array &)       const { return false; }
+    bool operator() (const Null &, const Tuple &)       const { return false; }
 
-    bool operator() (const UInt64 & l, const Null & r)      const { return false; }
+    bool operator() (const UInt64 &, const Null &)      const { return false; }
     bool operator() (const UInt64 & l, const UInt64 & r)    const { return l == r; }
     bool operator() (const UInt64 & l, const Int64 & r)     const { return accurate::equalsOp(l, r); }
     bool operator() (const UInt64 & l, const Float64 & r)   const { return accurate::equalsOp(l, r); }
-    bool operator() (const UInt64 & l, const String & r)    const { return false; }
-    bool operator() (const UInt64 & l, const Array & r)     const { return false; }
-    bool operator() (const UInt64 & l, const Tuple & r)     const { return false; }
+    bool operator() (const UInt64 &, const String &)    const { return false; }
+    bool operator() (const UInt64 &, const Array &)     const { return false; }
+    bool operator() (const UInt64 &, const Tuple &)     const { return false; }
 
-    bool operator() (const Int64 & l, const Null & r)       const { return false; }
+    bool operator() (const Int64 &, const Null &)       const { return false; }
     bool operator() (const Int64 & l, const UInt64 & r)     const { return accurate::equalsOp(l, r); }
     bool operator() (const Int64 & l, const Int64 & r)      const { return l == r; }
     bool operator() (const Int64 & l, const Float64 & r)    const { return accurate::equalsOp(l, r); }
-    bool operator() (const Int64 & l, const String & r)     const { return false; }
-    bool operator() (const Int64 & l, const Array & r)      const { return false; }
-    bool operator() (const Int64 & l, const Tuple & r)      const { return false; }
+    bool operator() (const Int64 &, const String &)     const { return false; }
+    bool operator() (const Int64 &, const Array &)      const { return false; }
+    bool operator() (const Int64 &, const Tuple &)      const { return false; }
 
-    bool operator() (const Float64 & l, const Null & r)     const { return false; }
+    bool operator() (const Float64 &, const Null &)     const { return false; }
     bool operator() (const Float64 & l, const UInt64 & r)   const { return accurate::equalsOp(l, r); }
     bool operator() (const Float64 & l, const Int64 & r)    const { return accurate::equalsOp(l, r); }
     bool operator() (const Float64 & l, const Float64 & r)  const { return l == r; }
-    bool operator() (const Float64 & l, const String & r)   const { return false; }
-    bool operator() (const Float64 & l, const Array & r)    const { return false; }
-    bool operator() (const Float64 & l, const Tuple & r)    const { return false; }
+    bool operator() (const Float64 &, const String &)   const { return false; }
+    bool operator() (const Float64 &, const Array &)    const { return false; }
+    bool operator() (const Float64 &, const Tuple &)    const { return false; }
 
-    bool operator() (const String & l, const Null & r)      const { return false; }
-    bool operator() (const String & l, const UInt64 & r)    const { return false; }
-    bool operator() (const String & l, const Int64 & r)     const { return false; }
-    bool operator() (const String & l, const Float64 & r)   const { return false; }
+    bool operator() (const String &, const Null &)      const { return false; }
+    bool operator() (const String &, const UInt64 &)    const { return false; }
+    bool operator() (const String &, const Int64 &)     const { return false; }
+    bool operator() (const String &, const Float64 &)   const { return false; }
     bool operator() (const String & l, const String & r)    const { return l == r; }
-    bool operator() (const String & l, const Array & r)     const { return false; }
-    bool operator() (const String & l, const Tuple & r)     const { return false; }
+    bool operator() (const String &, const Array &)     const { return false; }
+    bool operator() (const String &, const Tuple &)     const { return false; }
 
-    bool operator() (const Array & l, const Null & r)       const { return false; }
-    bool operator() (const Array & l, const UInt64 & r)     const { return false; }
-    bool operator() (const Array & l, const Int64 & r)      const { return false; }
-    bool operator() (const Array & l, const Float64 & r)    const { return false; }
-    bool operator() (const Array & l, const String & r)     const { return false; }
+    bool operator() (const Array &, const Null &)       const { return false; }
+    bool operator() (const Array &, const UInt64 &)     const { return false; }
+    bool operator() (const Array &, const Int64 &)      const { return false; }
+    bool operator() (const Array &, const Float64 &)    const { return false; }
+    bool operator() (const Array &, const String &)     const { return false; }
     bool operator() (const Array & l, const Array & r)      const { return l == r; }
-    bool operator() (const Array & l, const Tuple & r)      const { return false; }
+    bool operator() (const Array &, const Tuple &)      const { return false; }
 
-    bool operator() (const Tuple & l, const Null & r)       const { return false; }
-    bool operator() (const Tuple & l, const UInt64 & r)     const { return false; }
-    bool operator() (const Tuple & l, const Int64 & r)      const { return false; }
-    bool operator() (const Tuple & l, const Float64 & r)    const { return false; }
-    bool operator() (const Tuple & l, const String & r)     const { return false; }
-    bool operator() (const Tuple & l, const Array & r)      const { return false; }
+    bool operator() (const Tuple &, const Null &)       const { return false; }
+    bool operator() (const Tuple &, const UInt64 &)     const { return false; }
+    bool operator() (const Tuple &, const Int64 &)      const { return false; }
+    bool operator() (const Tuple &, const Float64 &)    const { return false; }
+    bool operator() (const Tuple &, const String &)     const { return false; }
+    bool operator() (const Tuple &, const Array &)      const { return false; }
     bool operator() (const Tuple & l, const Tuple & r)      const { return l == r; }
 };
 
 class FieldVisitorAccurateLess : public StaticVisitor<bool>
 {
 public:
-    bool operator() (const Null & l, const Null & r)        const { return false; }
-    bool operator() (const Null & l, const UInt64 & r)      const { return true; }
-    bool operator() (const Null & l, const Int64 & r)       const { return true; }
-    bool operator() (const Null & l, const Float64 & r)     const { return true; }
-    bool operator() (const Null & l, const String & r)      const { return true; }
-    bool operator() (const Null & l, const Array & r)       const { return true; }
-    bool operator() (const Null & l, const Tuple & r)       const { return true; }
+    bool operator() (const Null &, const Null &)        const { return false; }
+    bool operator() (const Null &, const UInt64 &)      const { return true; }
+    bool operator() (const Null &, const Int64 &)       const { return true; }
+    bool operator() (const Null &, const Float64 &)     const { return true; }
+    bool operator() (const Null &, const String &)      const { return true; }
+    bool operator() (const Null &, const Array &)       const { return true; }
+    bool operator() (const Null &, const Tuple &)       const { return true; }
 
-    bool operator() (const UInt64 & l, const Null & r)      const { return false; }
-    bool operator() (const UInt64 & l, const UInt64 & r)    const { return l < r; }
-    bool operator() (const UInt64 & l, const Int64 & r)     const { return accurate::lessOp(l, r); }
-    bool operator() (const UInt64 & l, const Float64 & r)   const { return accurate::lessOp(l, r); }
-    bool operator() (const UInt64 & l, const String & r)    const { return true; }
-    bool operator() (const UInt64 & l, const Array & r)     const { return true; }
-    bool operator() (const UInt64 & l, const Tuple & r)     const { return true; }
+    bool operator() (const UInt64 &, const Null &)      const { return false; }
+    bool operator() (const UInt64 & l, const UInt64 & r)  const { return l < r; }
+    bool operator() (const UInt64 & l, const Int64 & r)   const { return accurate::lessOp(l, r); }
+    bool operator() (const UInt64 & l, const Float64 & r) const { return accurate::lessOp(l, r); }
+    bool operator() (const UInt64 &, const String &)    const { return true; }
+    bool operator() (const UInt64 &, const Array &)     const { return true; }
+    bool operator() (const UInt64 &, const Tuple &)     const { return true; }
 
-    bool operator() (const Int64 & l, const Null & r)       const { return false; }
-    bool operator() (const Int64 & l, const UInt64 & r)     const { return accurate::lessOp(l, r); }
-    bool operator() (const Int64 & l, const Int64 & r)      const { return l < r; }
-    bool operator() (const Int64 & l, const Float64 & r)    const { return accurate::lessOp(l, r); }
-    bool operator() (const Int64 & l, const String & r)     const { return true; }
-    bool operator() (const Int64 & l, const Array & r)      const { return true; }
-    bool operator() (const Int64 & l, const Tuple & r)      const { return true; }
+    bool operator() (const Int64 &, const Null &)       const { return false; }
+    bool operator() (const Int64 & l, const UInt64 & r)  const { return accurate::lessOp(l, r); }
+    bool operator() (const Int64 & l, const Int64 & r)   const { return l < r; }
+    bool operator() (const Int64 & l, const Float64 & r) const { return accurate::lessOp(l, r); }
+    bool operator() (const Int64 &, const String &)     const { return true; }
+    bool operator() (const Int64 &, const Array &)      const { return true; }
+    bool operator() (const Int64 &, const Tuple &)      const { return true; }
 
-    bool operator() (const Float64 & l, const Null & r)     const { return false; }
-    bool operator() (const Float64 & l, const UInt64 & r)   const { return accurate::lessOp(l, r); }
-    bool operator() (const Float64 & l, const Int64 & r)    const { return accurate::lessOp(l, r); }
-    bool operator() (const Float64 & l, const Float64 & r)  const { return l < r; }
-    bool operator() (const Float64 & l, const String & r)   const { return true; }
-    bool operator() (const Float64 & l, const Array & r)    const { return true; }
-    bool operator() (const Float64 & l, const Tuple & r)    const { return true; }
+    bool operator() (const Float64 &, const Null &)     const { return false; }
+    bool operator() (const Float64 & l, const UInt64 & r)  const { return accurate::lessOp(l, r); }
+    bool operator() (const Float64 & l, const Int64 & r)   const { return accurate::lessOp(l, r); }
+    bool operator() (const Float64 & l, const Float64 & r) const { return l < r; }
+    bool operator() (const Float64 &, const String &)   const { return true; }
+    bool operator() (const Float64 &, const Array &)    const { return true; }
+    bool operator() (const Float64 &, const Tuple &)    const { return true; }
 
-    bool operator() (const String & l, const Null & r)      const { return false; }
-    bool operator() (const String & l, const UInt64 & r)    const { return false; }
-    bool operator() (const String & l, const Int64 & r)     const { return false; }
-    bool operator() (const String & l, const Float64 & r)   const { return false; }
-    bool operator() (const String & l, const String & r)    const { return l < r; }
-    bool operator() (const String & l, const Array & r)     const { return true; }
-    bool operator() (const String & l, const Tuple & r)     const { return true; }
+    bool operator() (const String &, const Null &)      const { return false; }
+    bool operator() (const String &, const UInt64 &)    const { return false; }
+    bool operator() (const String &, const Int64 &)     const { return false; }
+    bool operator() (const String &, const Float64 &)   const { return false; }
+    bool operator() (const String & l, const String & r) const { return l < r; }
+    bool operator() (const String &, const Array &)     const { return true; }
+    bool operator() (const String &, const Tuple &)     const { return true; }
 
-    bool operator() (const Array & l, const Null & r)       const { return false; }
-    bool operator() (const Array & l, const UInt64 & r)     const { return false; }
-    bool operator() (const Array & l, const Int64 & r)      const { return false; }
-    bool operator() (const Array & l, const Float64 & r)    const { return false; }
-    bool operator() (const Array & l, const String & r)     const { return false; }
-    bool operator() (const Array & l, const Array & r)      const { return l < r; }
-    bool operator() (const Array & l, const Tuple & r)      const { return false; }
+    bool operator() (const Array &, const Null &)       const { return false; }
+    bool operator() (const Array &, const UInt64 &)     const { return false; }
+    bool operator() (const Array &, const Int64 &)      const { return false; }
+    bool operator() (const Array &, const Float64 &)    const { return false; }
+    bool operator() (const Array &, const String &)     const { return false; }
+    bool operator() (const Array & l, const Array & r)  const { return l < r; }
+    bool operator() (const Array &, const Tuple &)      const { return false; }
 
-    bool operator() (const Tuple & l, const Null & r)       const { return false; }
-    bool operator() (const Tuple & l, const UInt64 & r)     const { return false; }
-    bool operator() (const Tuple & l, const Int64 & r)      const { return false; }
-    bool operator() (const Tuple & l, const Float64 & r)    const { return false; }
-    bool operator() (const Tuple & l, const String & r)     const { return false; }
-    bool operator() (const Tuple & l, const Array & r)      const { return false; }
-    bool operator() (const Tuple & l, const Tuple & r)      const { return l < r; }
+    bool operator() (const Tuple &, const Null &)       const { return false; }
+    bool operator() (const Tuple &, const UInt64 &)     const { return false; }
+    bool operator() (const Tuple &, const Int64 &)      const { return false; }
+    bool operator() (const Tuple &, const Float64 &)    const { return false; }
+    bool operator() (const Tuple &, const String &)     const { return false; }
+    bool operator() (const Tuple &, const Array &)      const { return false; }
+    bool operator() (const Tuple & l, const Tuple & r)  const { return l < r; }
 };
 
 /** Implements `+=` operation.
@@ -314,9 +314,9 @@ public:
     bool operator() (Int64 & x) const { x += get<Int64>(rhs); return x != 0; }
     bool operator() (Float64 & x) const { x += get<Float64>(rhs); return x != 0; }
 
-    bool operator() (Null & x) const { throw Exception("Cannot sum Nulls", ErrorCodes::LOGICAL_ERROR); }
-    bool operator() (String & x) const { throw Exception("Cannot sum Strings", ErrorCodes::LOGICAL_ERROR); }
-    bool operator() (Array & x) const { throw Exception("Cannot sum Arrays", ErrorCodes::LOGICAL_ERROR); }
+    bool operator() (Null &) const { throw Exception("Cannot sum Nulls", ErrorCodes::LOGICAL_ERROR); }
+    bool operator() (String &) const { throw Exception("Cannot sum Strings", ErrorCodes::LOGICAL_ERROR); }
+    bool operator() (Array &) const { throw Exception("Cannot sum Arrays", ErrorCodes::LOGICAL_ERROR); }
 };
 
 }
diff --git a/dbms/src/Common/LRUCache.h b/dbms/src/Common/LRUCache.h
index 387a5a85fd1..fe5f5fbb52c 100644
--- a/dbms/src/Common/LRUCache.h
+++ b/dbms/src/Common/LRUCache.h
@@ -16,7 +16,7 @@ namespace DB
 template <typename T>
 struct TrivialWeightFunction
 {
-    size_t operator()(const T & x) const
+    size_t operator()(const T &) const
     {
         return 1;
     }
@@ -188,14 +188,14 @@ private:
 
         InsertTokenHolder() = default;
 
-        void acquire(const Key * key_, const std::shared_ptr<InsertToken> & token_, std::lock_guard<std::mutex> & cache_lock)
+        void acquire(const Key * key_, const std::shared_ptr<InsertToken> & token_, [[maybe_unused]] std::lock_guard<std::mutex> & cache_lock)
         {
             key = key_;
             token = token_;
             ++token->refcount;
         }
 
-        void cleanup(std::lock_guard<std::mutex> & token_lock, std::lock_guard<std::mutex> & cache_lock)
+        void cleanup([[maybe_unused]] std::lock_guard<std::mutex> & token_lock, [[maybe_unused]] std::lock_guard<std::mutex> & cache_lock)
         {
             token->cache.insert_tokens.erase(*key);
             token->cleaned_up = true;
@@ -260,7 +260,7 @@ private:
 
     WeightFunction weight_function;
 
-    MappedPtr getImpl(const Key & key, std::lock_guard<std::mutex> & cache_lock)
+    MappedPtr getImpl(const Key & key, [[maybe_unused]] std::lock_guard<std::mutex> & cache_lock)
     {
         auto it = cells.find(key);
         if (it == cells.end())
@@ -277,7 +277,7 @@ private:
         return cell.value;
     }
 
-    void setImpl(const Key & key, const MappedPtr & mapped, std::lock_guard<std::mutex> & cache_lock)
+    void setImpl(const Key & key, const MappedPtr & mapped, [[maybe_unused]] std::lock_guard<std::mutex> & cache_lock)
     {
         auto res = cells.emplace(std::piecewise_construct,
             std::forward_as_tuple(key),
diff --git a/dbms/src/Common/ZooKeeper/ZooKeeper.cpp b/dbms/src/Common/ZooKeeper/ZooKeeper.cpp
index 94c5beac0dd..83df594e893 100644
--- a/dbms/src/Common/ZooKeeper/ZooKeeper.cpp
+++ b/dbms/src/Common/ZooKeeper/ZooKeeper.cpp
@@ -60,7 +60,7 @@ struct WatchContext
     }
 };
 
-void ZooKeeper::processCallback(zhandle_t * zh, int type, int state, const char * path, void * watcher_ctx)
+void ZooKeeper::processCallback(zhandle_t *, int type, int state, const char * path, void * watcher_ctx)
 {
     WatchContext * context = static_cast<WatchContext *>(watcher_ctx);
     context->process(type, state, path);
diff --git a/dbms/src/Common/tests/simple_cache.cpp b/dbms/src/Common/tests/simple_cache.cpp
index 2d37110c8da..93ddb30c6e9 100644
--- a/dbms/src/Common/tests/simple_cache.cpp
+++ b/dbms/src/Common/tests/simple_cache.cpp
@@ -9,7 +9,7 @@ int func(int x, int y)
 }
 
 
-int main(int argc, char ** argv)
+int main(int, char **)
 {
     SimpleCache<decltype(func), &func> func_cached;
 
diff --git a/dbms/src/Core/Field.h b/dbms/src/Core/Field.h
index affa2dcec96..95a605b458a 100644
--- a/dbms/src/Core/Field.h
+++ b/dbms/src/Core/Field.h
@@ -108,7 +108,7 @@ public:
 
     template <typename T>
     Field(T && rhs,
-        typename std::enable_if<!std::is_same<typename std::decay<T>::type, Field>::value, void>::type * unused = nullptr)
+        [[maybe_unused]] typename std::enable_if<!std::is_same<typename std::decay<T>::type, Field>::value, void>::type * unused = nullptr)
     {
         createConcrete(std::forward<T>(rhs));
     }
@@ -523,25 +523,25 @@ class WriteBuffer;
 /// It is assumed that all elements of the array have the same type.
 void readBinary(Array & x, ReadBuffer & buf);
 
-inline void readText(Array & x, ReadBuffer & buf) { throw Exception("Cannot read Array.", ErrorCodes::NOT_IMPLEMENTED); }
-inline void readQuoted(Array & x, ReadBuffer & buf) { throw Exception("Cannot read Array.", ErrorCodes::NOT_IMPLEMENTED); }
+inline void readText(Array &, ReadBuffer &) { throw Exception("Cannot read Array.", ErrorCodes::NOT_IMPLEMENTED); }
+inline void readQuoted(Array &, ReadBuffer &) { throw Exception("Cannot read Array.", ErrorCodes::NOT_IMPLEMENTED); }
 
 /// It is assumed that all elements of the array have the same type.
 void writeBinary(const Array & x, WriteBuffer & buf);
 
 void writeText(const Array & x, WriteBuffer & buf);
 
-inline void writeQuoted(const Array & x, WriteBuffer & buf) { throw Exception("Cannot write Array quoted.", ErrorCodes::NOT_IMPLEMENTED); }
+inline void writeQuoted(const Array &, WriteBuffer &) { throw Exception("Cannot write Array quoted.", ErrorCodes::NOT_IMPLEMENTED); }
 
 void readBinary(Tuple & x, ReadBuffer & buf);
 
-inline void readText(Tuple & x, ReadBuffer & buf) { throw Exception("Cannot read Tuple.", ErrorCodes::NOT_IMPLEMENTED); }
-inline void readQuoted(Tuple & x, ReadBuffer & buf) { throw Exception("Cannot read Tuple.", ErrorCodes::NOT_IMPLEMENTED); }
+inline void readText(Tuple &, ReadBuffer &) { throw Exception("Cannot read Tuple.", ErrorCodes::NOT_IMPLEMENTED); }
+inline void readQuoted(Tuple &, ReadBuffer &) { throw Exception("Cannot read Tuple.", ErrorCodes::NOT_IMPLEMENTED); }
 
 void writeBinary(const Tuple & x, WriteBuffer & buf);
 
 void writeText(const Tuple & x, WriteBuffer & buf);
 
-inline void writeQuoted(const Tuple & x, WriteBuffer & buf) { throw Exception("Cannot write Tuple quoted.", ErrorCodes::NOT_IMPLEMENTED); }
+inline void writeQuoted(const Tuple &, WriteBuffer &) { throw Exception("Cannot write Tuple quoted.", ErrorCodes::NOT_IMPLEMENTED); }
 
 }
diff --git a/dbms/src/Core/tests/rvo_test.cpp b/dbms/src/Core/tests/rvo_test.cpp
index aa6cc1a3a6b..7e04dcc244d 100644
--- a/dbms/src/Core/tests/rvo_test.cpp
+++ b/dbms/src/Core/tests/rvo_test.cpp
@@ -247,7 +247,7 @@ struct Factory3 : IFactory
 };
 
 
-int main(int argc, char ** argv)
+int main(int, char **)
 {
     srand(time(0));
 
diff --git a/dbms/src/DataStreams/DistinctBlockInputStream.cpp b/dbms/src/DataStreams/DistinctBlockInputStream.cpp
index dbb6d5b63f8..e354e4154be 100644
--- a/dbms/src/DataStreams/DistinctBlockInputStream.cpp
+++ b/dbms/src/DataStreams/DistinctBlockInputStream.cpp
@@ -124,7 +124,7 @@ void DistinctBlockInputStream::buildFilter(
         method.data.emplace(key, it, inserted);
 
         if (inserted)
-            method.onNewKey(*it, columns.size(), i, variants.string_pool);
+            method.onNewKey(*it, columns.size(), variants.string_pool);
 
         /// Emit the record if there is no such key in the current set yet.
         /// Skip it otherwise.
diff --git a/dbms/src/DataStreams/DistinctSortedBlockInputStream.cpp b/dbms/src/DataStreams/DistinctSortedBlockInputStream.cpp
index 166f6c2dd6f..c40ceb98bc6 100644
--- a/dbms/src/DataStreams/DistinctSortedBlockInputStream.cpp
+++ b/dbms/src/DataStreams/DistinctSortedBlockInputStream.cpp
@@ -147,7 +147,7 @@ bool DistinctSortedBlockInputStream::buildFilter(
 
         if (inserted)
         {
-            method.onNewKey(*it, columns.size(), i, variants.string_pool);
+            method.onNewKey(*it, columns.size(), variants.string_pool);
             has_new_data = true;
         }
 
diff --git a/dbms/src/IO/Operators.h b/dbms/src/IO/Operators.h
index f5218ae92f1..e5f0de9df42 100644
--- a/dbms/src/IO/Operators.h
+++ b/dbms/src/IO/Operators.h
@@ -47,10 +47,10 @@ template <> inline        WriteBuffer & operator<< (WriteBuffer & buf, const cha
 
 inline WriteBuffer & operator<< (WriteBuffer & buf, const char * x)     { writeCString(x, buf); return buf; }
 
-inline EscapeManipWriteBuffer &      operator<< (WriteBuffer & buf, EscapeManip x)      { return static_cast<EscapeManipWriteBuffer &>(buf); }
-inline QuoteManipWriteBuffer &       operator<< (WriteBuffer & buf, QuoteManip x)       { return static_cast<QuoteManipWriteBuffer &>(buf); }
-inline DoubleQuoteManipWriteBuffer & operator<< (WriteBuffer & buf, DoubleQuoteManip x) { return static_cast<DoubleQuoteManipWriteBuffer &>(buf); }
-inline BinaryManipWriteBuffer &      operator<< (WriteBuffer & buf, BinaryManip x)      { return static_cast<BinaryManipWriteBuffer &>(buf); }
+inline EscapeManipWriteBuffer &      operator<< (WriteBuffer & buf, EscapeManip)      { return static_cast<EscapeManipWriteBuffer &>(buf); }
+inline QuoteManipWriteBuffer &       operator<< (WriteBuffer & buf, QuoteManip)       { return static_cast<QuoteManipWriteBuffer &>(buf); }
+inline DoubleQuoteManipWriteBuffer & operator<< (WriteBuffer & buf, DoubleQuoteManip) { return static_cast<DoubleQuoteManipWriteBuffer &>(buf); }
+inline BinaryManipWriteBuffer &      operator<< (WriteBuffer & buf, BinaryManip)      { return static_cast<BinaryManipWriteBuffer &>(buf); }
 
 template <typename T> WriteBuffer & operator<< (EscapeManipWriteBuffer & buf,        const T & x) { writeText(x, buf);         return buf; }
 template <typename T> WriteBuffer & operator<< (QuoteManipWriteBuffer & buf,         const T & x) { writeQuoted(x, buf);       return buf; }
@@ -65,7 +65,7 @@ inline WriteBuffer & operator<< (BinaryManipWriteBuffer & buf,      const char *
 /// The manipulator calls the WriteBuffer method `next` - this makes the buffer reset. For nested buffers, the reset is not recursive.
 enum FlushManip { flush };
 
-inline WriteBuffer & operator<< (WriteBuffer & buf, FlushManip x) { buf.next(); return buf; }
+inline WriteBuffer & operator<< (WriteBuffer & buf, FlushManip) { buf.next(); return buf; }
 
 
 template <typename T> ReadBuffer & operator>> (ReadBuffer & buf, T & x)              { readText(x, buf);     return buf; }
@@ -75,10 +75,10 @@ template <> inline    ReadBuffer & operator>> (ReadBuffer & buf, char & x)
 /// If you specify a string literal for reading, this will mean - make sure there is a sequence of bytes and skip it.
 inline ReadBuffer & operator>> (ReadBuffer & buf, const char * x)     { assertString(x, buf); return buf; }
 
-inline EscapeManipReadBuffer &       operator>> (ReadBuffer & buf, EscapeManip x)      { return static_cast<EscapeManipReadBuffer &>(buf); }
-inline QuoteManipReadBuffer &        operator>> (ReadBuffer & buf, QuoteManip x)       { return static_cast<QuoteManipReadBuffer &>(buf); }
-inline DoubleQuoteManipReadBuffer &  operator>> (ReadBuffer & buf, DoubleQuoteManip x) { return static_cast<DoubleQuoteManipReadBuffer &>(buf); }
-inline BinaryManipReadBuffer &       operator>> (ReadBuffer & buf, BinaryManip x)      { return static_cast<BinaryManipReadBuffer &>(buf); }
+inline EscapeManipReadBuffer &       operator>> (ReadBuffer & buf, EscapeManip)      { return static_cast<EscapeManipReadBuffer &>(buf); }
+inline QuoteManipReadBuffer &        operator>> (ReadBuffer & buf, QuoteManip)       { return static_cast<QuoteManipReadBuffer &>(buf); }
+inline DoubleQuoteManipReadBuffer &  operator>> (ReadBuffer & buf, DoubleQuoteManip) { return static_cast<DoubleQuoteManipReadBuffer &>(buf); }
+inline BinaryManipReadBuffer &       operator>> (ReadBuffer & buf, BinaryManip)      { return static_cast<BinaryManipReadBuffer &>(buf); }
 
 template <typename T> ReadBuffer & operator>> (EscapeManipReadBuffer & buf,      T & x) { readText(x, buf);         return buf; }
 template <typename T> ReadBuffer & operator>> (QuoteManipReadBuffer & buf,       T & x) { readQuoted(x, buf);       return buf; }
diff --git a/dbms/src/IO/Progress.cpp b/dbms/src/IO/Progress.cpp
index 050f77211dc..ce46beb85c6 100644
--- a/dbms/src/IO/Progress.cpp
+++ b/dbms/src/IO/Progress.cpp
@@ -9,7 +9,7 @@
 namespace DB
 {
 
-void Progress::read(ReadBuffer & in, UInt64 server_revision)
+void Progress::read(ReadBuffer & in, UInt64 /*server_revision*/)
 {
     size_t new_rows = 0;
     size_t new_bytes = 0;
@@ -25,7 +25,7 @@ void Progress::read(ReadBuffer & in, UInt64 server_revision)
 }
 
 
-void Progress::write(WriteBuffer & out, UInt64 client_revision) const
+void Progress::write(WriteBuffer & out, UInt64 /*client_revision*/) const
 {
     writeVarUInt(rows.load(), out);
     writeVarUInt(bytes.load(), out);
diff --git a/dbms/src/IO/ReadBufferFromFile.cpp b/dbms/src/IO/ReadBufferFromFile.cpp
index 9b634582d44..3843c7cc2fc 100644
--- a/dbms/src/IO/ReadBufferFromFile.cpp
+++ b/dbms/src/IO/ReadBufferFromFile.cpp
@@ -63,7 +63,6 @@ ReadBufferFromFile::ReadBufferFromFile(
     int fd,
     const std::string & original_file_name,
     size_t buf_size,
-    int flags,
     char * existing_memory,
     size_t alignment)
     :
diff --git a/dbms/src/IO/ReadBufferFromFile.h b/dbms/src/IO/ReadBufferFromFile.h
index 087e612c6ee..9218e0738ca 100644
--- a/dbms/src/IO/ReadBufferFromFile.h
+++ b/dbms/src/IO/ReadBufferFromFile.h
@@ -29,7 +29,7 @@ public:
         char * existing_memory = nullptr, size_t alignment = 0);
 
     /// Use pre-opened file descriptor.
-    ReadBufferFromFile(int fd, const std::string & original_file_name = {}, size_t buf_size = DBMS_DEFAULT_BUFFER_SIZE, int flags = -1,
+    ReadBufferFromFile(int fd, const std::string & original_file_name = {}, size_t buf_size = DBMS_DEFAULT_BUFFER_SIZE,
         char * existing_memory = nullptr, size_t alignment = 0);
 
     ReadBufferFromFile(ReadBufferFromFile &&) = default;
diff --git a/dbms/src/IO/ReadHelpers.h b/dbms/src/IO/ReadHelpers.h
index 50849c44b4b..83510a71339 100644
--- a/dbms/src/IO/ReadHelpers.h
+++ b/dbms/src/IO/ReadHelpers.h
@@ -730,7 +730,7 @@ inline void readText(String & x, ReadBuffer & buf) { readEscapedString(x, buf);
 inline void readText(LocalDate & x, ReadBuffer & buf) { readDateText(x, buf); }
 inline void readText(LocalDateTime & x, ReadBuffer & buf) { readDateTimeText(x, buf); }
 inline void readText(UUID & x, ReadBuffer & buf) { readUUIDText(x, buf); }
-inline void readText(UInt128 & x, ReadBuffer & buf)
+inline void readText(UInt128 &, ReadBuffer &)
 {
     /** Because UInt128 isn't a natural type, without arithmetic operator and only use as an intermediary type -for UUID-
      *  it should never arrive here. But because we used the DataTypeNumber class we should have at least a definition of it.
@@ -825,7 +825,7 @@ inline void readCSV(String & x, ReadBuffer & buf, const char delimiter = ',') {
 inline void readCSV(LocalDate & x, ReadBuffer & buf) { readCSVSimple(x, buf); }
 inline void readCSV(LocalDateTime & x, ReadBuffer & buf) { readCSVSimple(x, buf); }
 inline void readCSV(UUID & x, ReadBuffer & buf) { readCSVSimple(x, buf); }
-inline void readCSV(UInt128 & x, ReadBuffer & buf)
+inline void readCSV(UInt128 &, ReadBuffer &)
 {
     /** Because UInt128 isn't a natural type, without arithmetic operator and only use as an intermediary type -for UUID-
      *  it should never arrive here. But because we used the DataTypeNumber class we should have at least a definition of it.
diff --git a/dbms/src/IO/WriteHelpers.h b/dbms/src/IO/WriteHelpers.h
index ac21ab33a33..6c5e846a3ee 100644
--- a/dbms/src/IO/WriteHelpers.h
+++ b/dbms/src/IO/WriteHelpers.h
@@ -671,7 +671,7 @@ inline void writeText(const char * x, size_t size, WriteBuffer & buf) { writeEsc
 inline void writeText(const LocalDate & x, WriteBuffer & buf) { writeDateText(x, buf); }
 inline void writeText(const LocalDateTime & x, WriteBuffer & buf) { writeDateTimeText(x, buf); }
 inline void writeText(const UUID & x, WriteBuffer & buf) { writeUUIDText(x, buf); }
-inline void writeText(const UInt128 & x, WriteBuffer & buf)
+inline void writeText(const UInt128 &, WriteBuffer &)
 {
     /** Because UInt128 isn't a natural type, without arithmetic operator and only use as an intermediary type -for UUID-
      *  it should never arrive here. But because we used the DataTypeNumber class we should have at least a definition of it.
@@ -739,7 +739,7 @@ inline void writeCSV(const String & x, WriteBuffer & buf) { writeCSVString<>(x,
 inline void writeCSV(const LocalDate & x, WriteBuffer & buf) { writeDoubleQuoted(x, buf); }
 inline void writeCSV(const LocalDateTime & x, WriteBuffer & buf) { writeDoubleQuoted(x, buf); }
 inline void writeCSV(const UUID & x, WriteBuffer & buf) { writeDoubleQuoted(x, buf); }
-inline void writeCSV(const UInt128, WriteBuffer & buf)
+inline void writeCSV(const UInt128, WriteBuffer &)
 {
     /** Because UInt128 isn't a natural type, without arithmetic operator and only use as an intermediary type -for UUID-
      *  it should never arrive here. But because we used the DataTypeNumber class we should have at least a definition of it.
diff --git a/dbms/src/Interpreters/AggregationCommon.h b/dbms/src/Interpreters/AggregationCommon.h
index 949ba9da719..32a4cbebd83 100644
--- a/dbms/src/Interpreters/AggregationCommon.h
+++ b/dbms/src/Interpreters/AggregationCommon.h
@@ -211,7 +211,7 @@ static inline UInt128 ALWAYS_INLINE hash128(
 
 /// Copy keys to the pool. Then put into pool StringRefs to them and return the pointer to the first.
 static inline StringRef * ALWAYS_INLINE placeKeysInPool(
-    size_t i, size_t keys_size, StringRefs & keys, Arena & pool)
+    size_t keys_size, StringRefs & keys, Arena & pool)
 {
     for (size_t j = 0; j < keys_size; ++j)
     {
@@ -291,7 +291,7 @@ inline StringRef ALWAYS_INLINE extractKeysAndPlaceInPoolContiguous(
 /** Serialize keys into a continuous chunk of memory.
   */
 static inline StringRef ALWAYS_INLINE serializeKeysToPoolContiguous(
-    size_t i, size_t keys_size, const ConstColumnPlainPtrs & key_columns, StringRefs & keys, Arena & pool)
+    size_t i, size_t keys_size, const ConstColumnPlainPtrs & key_columns, Arena & pool)
 {
     const char * begin = nullptr;
 
diff --git a/dbms/src/Interpreters/Aggregator.cpp b/dbms/src/Interpreters/Aggregator.cpp
index d0d6b3b9ade..6444336ce18 100644
--- a/dbms/src/Interpreters/Aggregator.cpp
+++ b/dbms/src/Interpreters/Aggregator.cpp
@@ -663,7 +663,7 @@ void NO_INLINE Aggregator::executeImplCase(
             /// exception-safety - if you can not allocate memory or create states, then destructors will not be called.
             aggregate_data = nullptr;
 
-            method.onNewKey(*it, params.keys_size, i, keys, *aggregates_pool);
+            method.onNewKey(*it, params.keys_size, keys, *aggregates_pool);
 
             AggregateDataPtr place = aggregates_pool->alloc(total_size_of_aggregate_states);
             createAggregateStates(place);
@@ -1944,7 +1944,7 @@ void NO_INLINE Aggregator::mergeStreamsImplCase(
             AggregateDataPtr & aggregate_data = Method::getAggregateData(it->second);
             aggregate_data = nullptr;
 
-            method.onNewKey(*it, params.keys_size, i, keys, *aggregates_pool);
+            method.onNewKey(*it, params.keys_size, keys, *aggregates_pool);
 
             AggregateDataPtr place = aggregates_pool->alloc(total_size_of_aggregate_states);
             createAggregateStates(place);
diff --git a/dbms/src/Interpreters/Aggregator.h b/dbms/src/Interpreters/Aggregator.h
index ee0b0e6cd87..c6968410c9f 100644
--- a/dbms/src/Interpreters/Aggregator.h
+++ b/dbms/src/Interpreters/Aggregator.h
@@ -137,7 +137,7 @@ struct AggregationMethodOneNumber
 
     /** Place additional data, if necessary, in case a new key was inserted into the hash table.
       */
-    static void onNewKey(typename Data::value_type & value, size_t keys_size, size_t i, StringRefs & keys, Arena & pool)
+    static void onNewKey(typename Data::value_type & value, size_t keys_size, StringRefs & keys, Arena & pool)
     {
     }
 
@@ -205,7 +205,7 @@ struct AggregationMethodString
     static AggregateDataPtr & getAggregateData(Mapped & value)                { return value; }
     static const AggregateDataPtr & getAggregateData(const Mapped & value)    { return value; }
 
-    static void onNewKey(typename Data::value_type & value, size_t keys_size, size_t i, StringRefs & keys, Arena & pool)
+    static void onNewKey(typename Data::value_type & value, size_t keys_size, StringRefs & keys, Arena & pool)
     {
         value.first.data = pool.insert(value.first.data, value.first.size);
     }
@@ -266,7 +266,7 @@ struct AggregationMethodFixedString
     static AggregateDataPtr & getAggregateData(Mapped & value)                { return value; }
     static const AggregateDataPtr & getAggregateData(const Mapped & value)    { return value; }
 
-    static void onNewKey(typename Data::value_type & value, size_t keys_size, size_t i, StringRefs & keys, Arena & pool)
+    static void onNewKey(typename Data::value_type & value, size_t keys_size, StringRefs & keys, Arena & pool)
     {
         value.first.data = pool.insert(value.first.data, value.first.size);
     }
@@ -428,7 +428,7 @@ struct AggregationMethodKeysFixed
     static AggregateDataPtr & getAggregateData(Mapped & value)                { return value; }
     static const AggregateDataPtr & getAggregateData(const Mapped & value)    { return value; }
 
-    static void onNewKey(typename Data::value_type & value, size_t keys_size, size_t i, StringRefs & keys, Arena & pool)
+    static void onNewKey(typename Data::value_type & value, size_t keys_size, StringRefs & keys, Arena & pool)
     {
     }
 
@@ -525,7 +525,7 @@ struct AggregationMethodConcat
     static AggregateDataPtr & getAggregateData(Mapped & value)                { return value; }
     static const AggregateDataPtr & getAggregateData(const Mapped & value)    { return value; }
 
-    static void onNewKey(typename Data::value_type & value, size_t keys_size, size_t i, StringRefs & keys, Arena & pool)
+    static void onNewKey(typename Data::value_type & value, size_t keys_size, StringRefs & keys, Arena & pool)
     {
     }
 
@@ -603,14 +603,14 @@ struct AggregationMethodSerialized
             StringRefs & keys,
             Arena & pool) const
         {
-            return serializeKeysToPoolContiguous(i, keys_size, key_columns, keys, pool);
+            return serializeKeysToPoolContiguous(i, keys_size, key_columns, pool);
         }
     };
 
     static AggregateDataPtr & getAggregateData(Mapped & value)                { return value; }
     static const AggregateDataPtr & getAggregateData(const Mapped & value)    { return value; }
 
-    static void onNewKey(typename Data::value_type & value, size_t keys_size, size_t i, StringRefs & keys, Arena & pool)
+    static void onNewKey(typename Data::value_type & value, size_t keys_size, StringRefs & keys, Arena & pool)
     {
     }
 
@@ -669,9 +669,9 @@ struct AggregationMethodHashed
     static AggregateDataPtr & getAggregateData(Mapped & value)                { return value.second; }
     static const AggregateDataPtr & getAggregateData(const Mapped & value)    { return value.second; }
 
-    static void onNewKey(typename Data::value_type & value, size_t keys_size, size_t i, StringRefs & keys, Arena & pool)
+    static void onNewKey(typename Data::value_type & value, size_t keys_size, StringRefs & keys, Arena & pool)
     {
-        value.second.first = placeKeysInPool(i, keys_size, keys, pool);
+        value.second.first = placeKeysInPool(keys_size, keys, pool);
     }
 
     static void onExistingKey(const Key & key, StringRefs & keys, Arena & pool) {}
diff --git a/dbms/src/Interpreters/Set.cpp b/dbms/src/Interpreters/Set.cpp
index 38cfa79b46d..c6cf930d794 100644
--- a/dbms/src/Interpreters/Set.cpp
+++ b/dbms/src/Interpreters/Set.cpp
@@ -87,7 +87,7 @@ void NO_INLINE Set::insertFromBlockImplCase(
         method.data.emplace(key, it, inserted);
 
         if (inserted)
-            method.onNewKey(*it, keys_size, i, variants.string_pool);
+            method.onNewKey(*it, keys_size, variants.string_pool);
     }
 }
 
diff --git a/dbms/src/Interpreters/SetVariants.h b/dbms/src/Interpreters/SetVariants.h
index 985514c6e74..2a1d2706f97 100644
--- a/dbms/src/Interpreters/SetVariants.h
+++ b/dbms/src/Interpreters/SetVariants.h
@@ -53,7 +53,7 @@ struct SetMethodOneNumber
 
     /** Place additional data, if necessary, in case a new key was inserted into the hash table.
       */
-    static void onNewKey(typename Data::value_type & value, size_t keys_size, size_t i, Arena & pool) {}
+    static void onNewKey(typename Data::value_type & value, size_t keys_size, Arena & pool) {}
 };
 
 /// For the case where there is one string key.
@@ -90,7 +90,7 @@ struct SetMethodString
         }
     };
 
-    static void onNewKey(typename Data::value_type & value, size_t keys_size, size_t i, Arena & pool)
+    static void onNewKey(typename Data::value_type & value, size_t keys_size, Arena & pool)
     {
         value.data = pool.insert(value.data, value.size);
     }
@@ -128,7 +128,7 @@ struct SetMethodFixedString
         }
     };
 
-    static void onNewKey(typename Data::value_type & value, size_t keys_size, size_t i, Arena & pool)
+    static void onNewKey(typename Data::value_type & value, size_t keys_size, Arena & pool)
     {
         value.data = pool.insert(value.data, value.size);
     }
@@ -268,7 +268,7 @@ struct SetMethodKeysFixed
         }
     };
 
-    static void onNewKey(typename Data::value_type & value, size_t keys_size, size_t i, Arena & pool) {}
+    static void onNewKey(typename Data::value_type & value, size_t keys_size, Arena & pool) {}
 };
 
 /// For other cases. 128 bit hash from the key.
@@ -296,7 +296,7 @@ struct SetMethodHashed
         }
     };
 
-    static void onNewKey(typename Data::value_type & value, size_t keys_size, size_t i, Arena & pool) {}
+    static void onNewKey(typename Data::value_type & value, size_t keys_size, Arena & pool) {}
 };
 
 
diff --git a/dbms/src/Interpreters/SpecializedAggregator.h b/dbms/src/Interpreters/SpecializedAggregator.h
index 5d143905f96..2cda0037bb5 100644
--- a/dbms/src/Interpreters/SpecializedAggregator.h
+++ b/dbms/src/Interpreters/SpecializedAggregator.h
@@ -190,7 +190,7 @@ void NO_INLINE Aggregator::executeSpecializedCase(
             AggregateDataPtr & aggregate_data = Method::getAggregateData(it->second);
             aggregate_data = nullptr;
 
-            method.onNewKey(*it, params.keys_size, i, keys, *aggregates_pool);
+            method.onNewKey(*it, params.keys_size, keys, *aggregates_pool);
 
             AggregateDataPtr place = aggregates_pool->alloc(total_size_of_aggregate_states);
 
diff --git a/dbms/tests/external_dictionaries/dictionary_library/dictionary_library.cpp b/dbms/tests/external_dictionaries/dictionary_library/dictionary_library.cpp
index fa2c333766f..617ecea7852 100644
--- a/dbms/tests/external_dictionaries/dictionary_library/dictionary_library.cpp
+++ b/dbms/tests/external_dictionaries/dictionary_library/dictionary_library.cpp
@@ -72,7 +72,7 @@ void * ClickHouseDictionary_v1_loadIds(
     return nullptr;
 }
 
-void * ClickHouseDictionary_v1_loadAll(void * data_ptr, ClickHouseLibrary::CStrings * settings, ClickHouseLibrary::CStrings * columns)
+void * ClickHouseDictionary_v1_loadAll(void * data_ptr, ClickHouseLibrary::CStrings * settings, ClickHouseLibrary::CStrings * /*columns*/)
 {
     auto ptr = static_cast<DataHolder *>(data_ptr);
     std::cerr << "loadAll lib call ptr=" << data_ptr << " => " << ptr << "\n";