diff --git a/dbms/programs/client/Client.cpp b/dbms/programs/client/Client.cpp
index 7236fcdb6b2..23f15f0daf0 100644
--- a/dbms/programs/client/Client.cpp
+++ b/dbms/programs/client/Client.cpp
@@ -99,13 +99,9 @@ namespace ErrorCodes
     extern const int NETWORK_ERROR;
     extern const int NO_DATA_TO_INSERT;
     extern const int BAD_ARGUMENTS;
-    extern const int CANNOT_READ_HISTORY;
-    extern const int CANNOT_APPEND_HISTORY;
     extern const int UNKNOWN_PACKET_FROM_SERVER;
     extern const int UNEXPECTED_PACKET_FROM_SERVER;
     extern const int CLIENT_OUTPUT_FORMAT_SPECIFIED;
-    extern const int CANNOT_SET_SIGNAL_HANDLER;
-    extern const int SYSTEM_ERROR;
     extern const int INVALID_USAGE_OF_INPUT;
 }
 
diff --git a/dbms/programs/client/Suggest.h b/dbms/programs/client/Suggest.h
index bd4f239ddc7..6c81a388ea7 100644
--- a/dbms/programs/client/Suggest.h
+++ b/dbms/programs/client/Suggest.h
@@ -12,7 +12,6 @@ namespace DB
 
 namespace ErrorCodes
 {
-    extern const int UNKNOWN_PACKET_FROM_SERVER;
 }
 
 class Suggest : public LineReader::Suggest, boost::noncopyable
diff --git a/dbms/programs/copier/Internals.h b/dbms/programs/copier/Internals.h
index c1377a250d8..4160336154b 100644
--- a/dbms/programs/copier/Internals.h
+++ b/dbms/programs/copier/Internals.h
@@ -74,11 +74,6 @@ namespace DB
 
 namespace ErrorCodes
 {
-    extern const int NO_ZOOKEEPER;
-    extern const int BAD_ARGUMENTS;
-    extern const int UNKNOWN_TABLE;
-    extern const int UNFINISHED;
-    extern const int UNKNOWN_ELEMENT_IN_CONFIG;
 }
 
 
diff --git a/dbms/programs/server/HTTPHandler.cpp b/dbms/programs/server/HTTPHandler.cpp
index 3708b306b00..ddb7427015a 100644
--- a/dbms/programs/server/HTTPHandler.cpp
+++ b/dbms/programs/server/HTTPHandler.cpp
@@ -41,8 +41,6 @@ namespace DB
 
 namespace ErrorCodes
 {
-    extern const int READONLY;
-    extern const int UNKNOWN_COMPRESSION_METHOD;
 
     extern const int CANNOT_PARSE_TEXT;
     extern const int CANNOT_PARSE_ESCAPE_SEQUENCE;
diff --git a/dbms/programs/server/MySQLHandler.cpp b/dbms/programs/server/MySQLHandler.cpp
index 262132f6acc..389ae5b3a65 100644
--- a/dbms/programs/server/MySQLHandler.cpp
+++ b/dbms/programs/server/MySQLHandler.cpp
@@ -37,7 +37,6 @@ using Poco::Net::SSLManager;
 namespace ErrorCodes
 {
     extern const int MYSQL_CLIENT_INSUFFICIENT_CAPABILITIES;
-    extern const int OPENSSL_ERROR;
     extern const int SUPPORT_IS_DISABLED;
 }
 
diff --git a/dbms/programs/server/MySQLHandlerFactory.cpp b/dbms/programs/server/MySQLHandlerFactory.cpp
index 576ef4d5170..dceb3d2293e 100644
--- a/dbms/programs/server/MySQLHandlerFactory.cpp
+++ b/dbms/programs/server/MySQLHandlerFactory.cpp
@@ -19,7 +19,6 @@ namespace ErrorCodes
     extern const int CANNOT_OPEN_FILE;
     extern const int NO_ELEMENTS_IN_CONFIG;
     extern const int OPENSSL_ERROR;
-    extern const int SYSTEM_ERROR;
 }
 
 MySQLHandlerFactory::MySQLHandlerFactory(IServer & server_)
diff --git a/dbms/programs/server/Server.cpp b/dbms/programs/server/Server.cpp
index b97ed1cea2a..2c02a07c2d0 100644
--- a/dbms/programs/server/Server.cpp
+++ b/dbms/programs/server/Server.cpp
@@ -116,7 +116,6 @@ namespace ErrorCodes
     extern const int FAILED_TO_GETPWUID;
     extern const int MISMATCHING_USERS_FOR_PROCESS_AND_DATA;
     extern const int NETWORK_ERROR;
-    extern const int PATH_ACCESS_DENIED;
 }
 
 
diff --git a/dbms/programs/server/TCPHandler.cpp b/dbms/programs/server/TCPHandler.cpp
index 8fb3c2c6c76..98201d7c893 100644
--- a/dbms/programs/server/TCPHandler.cpp
+++ b/dbms/programs/server/TCPHandler.cpp
@@ -44,7 +44,6 @@ namespace ErrorCodes
     extern const int UNKNOWN_EXCEPTION;
     extern const int UNKNOWN_PACKET_FROM_CLIENT;
     extern const int POCO_EXCEPTION;
-    extern const int STD_EXCEPTION;
     extern const int SOCKET_TIMEOUT;
     extern const int UNEXPECTED_PACKET_FROM_CLIENT;
 }
diff --git a/dbms/src/Access/AccessRights.cpp b/dbms/src/Access/AccessRights.cpp
index 963cc84fab5..4d33463c3f1 100644
--- a/dbms/src/Access/AccessRights.cpp
+++ b/dbms/src/Access/AccessRights.cpp
@@ -9,7 +9,6 @@ namespace DB
 namespace ErrorCodes
 {
     extern const int INVALID_GRANT;
-    extern const int LOGICAL_ERROR;
 }
 
 
diff --git a/dbms/src/Access/IAccessStorage.cpp b/dbms/src/Access/IAccessStorage.cpp
index 1c6a79b2fb2..d3a0edf3ba0 100644
--- a/dbms/src/Access/IAccessStorage.cpp
+++ b/dbms/src/Access/IAccessStorage.cpp
@@ -15,7 +15,6 @@ namespace ErrorCodes
     extern const int BAD_CAST;
     extern const int ACCESS_ENTITY_NOT_FOUND;
     extern const int ACCESS_ENTITY_ALREADY_EXISTS;
-    extern const int ACCESS_ENTITY_FOUND_DUPLICATES;
     extern const int ACCESS_ENTITY_STORAGE_READONLY;
     extern const int UNKNOWN_USER;
     extern const int UNKNOWN_ROLE;
diff --git a/dbms/src/Access/MultipleAccessStorage.cpp b/dbms/src/Access/MultipleAccessStorage.cpp
index 9306e2bfff7..bcf978fd876 100644
--- a/dbms/src/Access/MultipleAccessStorage.cpp
+++ b/dbms/src/Access/MultipleAccessStorage.cpp
@@ -7,7 +7,6 @@ namespace DB
 {
 namespace ErrorCodes
 {
-    extern const int ACCESS_ENTITY_NOT_FOUND;
     extern const int ACCESS_ENTITY_FOUND_DUPLICATES;
 }
 
diff --git a/dbms/src/AggregateFunctions/AggregateFunctionAvg.h b/dbms/src/AggregateFunctions/AggregateFunctionAvg.h
index 35bb16550a7..06cc8c3bd7d 100644
--- a/dbms/src/AggregateFunctions/AggregateFunctionAvg.h
+++ b/dbms/src/AggregateFunctions/AggregateFunctionAvg.h
@@ -14,7 +14,6 @@ namespace DB
 {
 namespace ErrorCodes
 {
-    extern const int LOGICAL_ERROR;
 }
 
 template <typename T, typename Denominator>
diff --git a/dbms/src/AggregateFunctions/AggregateFunctionCount.h b/dbms/src/AggregateFunctions/AggregateFunctionCount.h
index c63d02931cf..3e153d89d01 100644
--- a/dbms/src/AggregateFunctions/AggregateFunctionCount.h
+++ b/dbms/src/AggregateFunctions/AggregateFunctionCount.h
@@ -21,7 +21,6 @@ struct AggregateFunctionCountData
 namespace ErrorCodes
 {
     extern const int LOGICAL_ERROR;
-    extern const int NUMBER_OF_ARGUMENTS_DOESNT_MATCH;
 }
 
 
diff --git a/dbms/src/AggregateFunctions/AggregateFunctionForEach.cpp b/dbms/src/AggregateFunctions/AggregateFunctionForEach.cpp
index e8f4c7ec357..e6530177712 100644
--- a/dbms/src/AggregateFunctions/AggregateFunctionForEach.cpp
+++ b/dbms/src/AggregateFunctions/AggregateFunctionForEach.cpp
@@ -9,7 +9,6 @@ namespace DB
 
 namespace ErrorCodes
 {
-    extern const int NUMBER_OF_ARGUMENTS_DOESNT_MATCH;
 }
 
 class AggregateFunctionCombinatorForEach final : public IAggregateFunctionCombinator
diff --git a/dbms/src/AggregateFunctions/AggregateFunctionForEach.h b/dbms/src/AggregateFunctions/AggregateFunctionForEach.h
index 1b32eaeac46..eaaa2077731 100644
--- a/dbms/src/AggregateFunctions/AggregateFunctionForEach.h
+++ b/dbms/src/AggregateFunctions/AggregateFunctionForEach.h
@@ -16,7 +16,6 @@ namespace DB
 
 namespace ErrorCodes
 {
-    extern const int PARAMETER_OUT_OF_BOUND;
     extern const int NUMBER_OF_ARGUMENTS_DOESNT_MATCH;
     extern const int SIZES_OF_ARRAYS_DOESNT_MATCH;
 }
diff --git a/dbms/src/AggregateFunctions/AggregateFunctionGroupArray.h b/dbms/src/AggregateFunctions/AggregateFunctionGroupArray.h
index 33e3db5b787..afee81a8d66 100644
--- a/dbms/src/AggregateFunctions/AggregateFunctionGroupArray.h
+++ b/dbms/src/AggregateFunctions/AggregateFunctionGroupArray.h
@@ -27,7 +27,6 @@ namespace DB
 namespace ErrorCodes
 {
     extern const int TOO_LARGE_ARRAY_SIZE;
-    extern const int LOGICAL_ERROR;
 }
 
 enum class Sampler
diff --git a/dbms/src/AggregateFunctions/AggregateFunctionGroupArrayMoving.h b/dbms/src/AggregateFunctions/AggregateFunctionGroupArrayMoving.h
index 0e6d1af6a1b..7a21edce27b 100644
--- a/dbms/src/AggregateFunctions/AggregateFunctionGroupArrayMoving.h
+++ b/dbms/src/AggregateFunctions/AggregateFunctionGroupArrayMoving.h
@@ -26,7 +26,6 @@ namespace DB
 namespace ErrorCodes
 {
     extern const int TOO_LARGE_ARRAY_SIZE;
-    extern const int LOGICAL_ERROR;
 }
 
 
diff --git a/dbms/src/AggregateFunctions/AggregateFunctionMLMethod.h b/dbms/src/AggregateFunctions/AggregateFunctionMLMethod.h
index d23a3dbcf62..d02bb5c8081 100644
--- a/dbms/src/AggregateFunctions/AggregateFunctionMLMethod.h
+++ b/dbms/src/AggregateFunctions/AggregateFunctionMLMethod.h
@@ -14,7 +14,6 @@ namespace DB
 namespace ErrorCodes
 {
     extern const int NUMBER_OF_ARGUMENTS_DOESNT_MATCH;
-    extern const int BAD_ARGUMENTS;
     extern const int BAD_CAST;
 }
 
diff --git a/dbms/src/AggregateFunctions/AggregateFunctionMerge.cpp b/dbms/src/AggregateFunctions/AggregateFunctionMerge.cpp
index d54ff99f25b..8fdcc9223a1 100644
--- a/dbms/src/AggregateFunctions/AggregateFunctionMerge.cpp
+++ b/dbms/src/AggregateFunctions/AggregateFunctionMerge.cpp
@@ -10,7 +10,6 @@ namespace DB
 namespace ErrorCodes
 {
     extern const int NUMBER_OF_ARGUMENTS_DOESNT_MATCH;
-    extern const int BAD_ARGUMENTS;
 }
 
 class AggregateFunctionCombinatorMerge final : public IAggregateFunctionCombinator
diff --git a/dbms/src/AggregateFunctions/AggregateFunctionOrFill.h b/dbms/src/AggregateFunctions/AggregateFunctionOrFill.h
index 42f6210e7d1..f69404ea393 100644
--- a/dbms/src/AggregateFunctions/AggregateFunctionOrFill.h
+++ b/dbms/src/AggregateFunctions/AggregateFunctionOrFill.h
@@ -11,7 +11,6 @@ namespace DB
 
 namespace ErrorCodes
 {
-    extern const int ARGUMENT_OUT_OF_BOUND;
 }
 
 /**
diff --git a/dbms/src/AggregateFunctions/AggregateFunctionQuantile.cpp b/dbms/src/AggregateFunctions/AggregateFunctionQuantile.cpp
index 43cc7acf5cb..898e692865f 100644
--- a/dbms/src/AggregateFunctions/AggregateFunctionQuantile.cpp
+++ b/dbms/src/AggregateFunctions/AggregateFunctionQuantile.cpp
@@ -11,7 +11,6 @@ namespace DB
 
 namespace ErrorCodes
 {
-    extern const int NUMBER_OF_ARGUMENTS_DOESNT_MATCH;
 }
 
 namespace
diff --git a/dbms/src/AggregateFunctions/AggregateFunctionRetention.h b/dbms/src/AggregateFunctions/AggregateFunctionRetention.h
index 35df3b68fb7..20f288b310d 100644
--- a/dbms/src/AggregateFunctions/AggregateFunctionRetention.h
+++ b/dbms/src/AggregateFunctions/AggregateFunctionRetention.h
@@ -21,8 +21,6 @@ namespace DB
 {
 namespace ErrorCodes
 {
-extern const int NUMBER_OF_ARGUMENTS_DOESNT_MATCH;
-extern const int TOO_MANY_ARGUMENTS_FOR_FUNCTION;
 }
 
 struct AggregateFunctionRetentionData
diff --git a/dbms/src/AggregateFunctions/AggregateFunctionSequenceMatch.h b/dbms/src/AggregateFunctions/AggregateFunctionSequenceMatch.h
index 47240db8b0d..5d4a7098951 100644
--- a/dbms/src/AggregateFunctions/AggregateFunctionSequenceMatch.h
+++ b/dbms/src/AggregateFunctions/AggregateFunctionSequenceMatch.h
@@ -19,8 +19,6 @@ namespace DB
 namespace ErrorCodes
 {
     extern const int TOO_SLOW;
-    extern const int TOO_FEW_ARGUMENTS_FOR_FUNCTION;
-    extern const int TOO_MANY_ARGUMENTS_FOR_FUNCTION;
     extern const int SYNTAX_ERROR;
     extern const int BAD_ARGUMENTS;
     extern const int LOGICAL_ERROR;
diff --git a/dbms/src/AggregateFunctions/AggregateFunctionSimpleLinearRegression.h b/dbms/src/AggregateFunctions/AggregateFunctionSimpleLinearRegression.h
index fcd4d113f1f..c9dd22a0649 100644
--- a/dbms/src/AggregateFunctions/AggregateFunctionSimpleLinearRegression.h
+++ b/dbms/src/AggregateFunctions/AggregateFunctionSimpleLinearRegression.h
@@ -16,7 +16,6 @@ namespace DB
 
 namespace ErrorCodes
 {
-    extern const int ILLEGAL_TYPE_OF_ARGUMENT;
 }
 
 template <typename X, typename Y, typename Ret>
diff --git a/dbms/src/AggregateFunctions/AggregateFunctionState.cpp b/dbms/src/AggregateFunctions/AggregateFunctionState.cpp
index ee312cba9ac..02f023fc8cf 100644
--- a/dbms/src/AggregateFunctions/AggregateFunctionState.cpp
+++ b/dbms/src/AggregateFunctions/AggregateFunctionState.cpp
@@ -10,7 +10,6 @@ namespace DB
 
 namespace ErrorCodes
 {
-    extern const int NUMBER_OF_ARGUMENTS_DOESNT_MATCH;
     extern const int BAD_ARGUMENTS;
 }
 
diff --git a/dbms/src/AggregateFunctions/AggregateFunctionSumMap.h b/dbms/src/AggregateFunctions/AggregateFunctionSumMap.h
index 9b1f164bdd2..88f99b73841 100644
--- a/dbms/src/AggregateFunctions/AggregateFunctionSumMap.h
+++ b/dbms/src/AggregateFunctions/AggregateFunctionSumMap.h
@@ -24,8 +24,6 @@ namespace DB
 namespace ErrorCodes
 {
     extern const int LOGICAL_ERROR;
-    extern const int ILLEGAL_TYPE_OF_ARGUMENT;
-    extern const int NUMBER_OF_ARGUMENTS_DOESNT_MATCH;
 }
 
 template <typename T>
diff --git a/dbms/src/AggregateFunctions/AggregateFunctionTimeSeriesGroupSum.h b/dbms/src/AggregateFunctions/AggregateFunctionTimeSeriesGroupSum.h
index 06748bf7385..d2447ccaacd 100644
--- a/dbms/src/AggregateFunctions/AggregateFunctionTimeSeriesGroupSum.h
+++ b/dbms/src/AggregateFunctions/AggregateFunctionTimeSeriesGroupSum.h
@@ -25,8 +25,6 @@ namespace DB
 {
 namespace ErrorCodes
 {
-    extern const int NUMBER_OF_ARGUMENTS_DOESNT_MATCH;
-    extern const int TOO_MANY_ARGUMENTS_FOR_FUNCTION;
 }
 template <bool rate>
 struct AggregateFunctionTimeSeriesGroupSumData
diff --git a/dbms/src/AggregateFunctions/AggregateFunctionUniq.cpp b/dbms/src/AggregateFunctions/AggregateFunctionUniq.cpp
index dc2c5d21541..1d079550124 100644
--- a/dbms/src/AggregateFunctions/AggregateFunctionUniq.cpp
+++ b/dbms/src/AggregateFunctions/AggregateFunctionUniq.cpp
@@ -17,7 +17,6 @@ namespace DB
 
 namespace ErrorCodes
 {
-    extern const int ILLEGAL_TYPE_OF_ARGUMENT;
     extern const int NUMBER_OF_ARGUMENTS_DOESNT_MATCH;
 }
 
diff --git a/dbms/src/AggregateFunctions/AggregateFunctionUniqCombined.cpp b/dbms/src/AggregateFunctions/AggregateFunctionUniqCombined.cpp
index 9c547048b1e..bab63677eaa 100644
--- a/dbms/src/AggregateFunctions/AggregateFunctionUniqCombined.cpp
+++ b/dbms/src/AggregateFunctions/AggregateFunctionUniqCombined.cpp
@@ -13,7 +13,6 @@ namespace DB
 {
 namespace ErrorCodes
 {
-    extern const int ILLEGAL_TYPE_OF_ARGUMENT;
     extern const int NUMBER_OF_ARGUMENTS_DOESNT_MATCH;
     extern const int ARGUMENT_OUT_OF_BOUND;
 }
diff --git a/dbms/src/AggregateFunctions/AggregateFunctionUniqUpTo.cpp b/dbms/src/AggregateFunctions/AggregateFunctionUniqUpTo.cpp
index 3d05c77c61c..f787bb7f7bf 100644
--- a/dbms/src/AggregateFunctions/AggregateFunctionUniqUpTo.cpp
+++ b/dbms/src/AggregateFunctions/AggregateFunctionUniqUpTo.cpp
@@ -13,7 +13,6 @@ namespace DB
 
 namespace ErrorCodes
 {
-    extern const int ILLEGAL_TYPE_OF_ARGUMENT;
     extern const int NUMBER_OF_ARGUMENTS_DOESNT_MATCH;
     extern const int ARGUMENT_OUT_OF_BOUND;
 }
diff --git a/dbms/src/AggregateFunctions/AggregateFunctionWindowFunnel.h b/dbms/src/AggregateFunctions/AggregateFunctionWindowFunnel.h
index 8aa3e452113..930afae9f67 100644
--- a/dbms/src/AggregateFunctions/AggregateFunctionWindowFunnel.h
+++ b/dbms/src/AggregateFunctions/AggregateFunctionWindowFunnel.h
@@ -18,8 +18,6 @@ namespace DB
 
 namespace ErrorCodes
 {
-    extern const int NUMBER_OF_ARGUMENTS_DOESNT_MATCH;
-    extern const int ILLEGAL_TYPE_OF_ARGUMENT;
 }
 
 struct ComparePairFirst final
diff --git a/dbms/src/Client/Connection.cpp b/dbms/src/Client/Connection.cpp
index b4190c1ca66..f530652caae 100644
--- a/dbms/src/Client/Connection.cpp
+++ b/dbms/src/Client/Connection.cpp
@@ -44,7 +44,6 @@ namespace ErrorCodes
 {
     extern const int NETWORK_ERROR;
     extern const int SOCKET_TIMEOUT;
-    extern const int SERVER_REVISION_IS_TOO_OLD;
     extern const int UNEXPECTED_PACKET_FROM_SERVER;
     extern const int UNKNOWN_PACKET_FROM_SERVER;
     extern const int SUPPORT_IS_DISABLED;
diff --git a/dbms/src/Columns/ColumnDecimal.h b/dbms/src/Columns/ColumnDecimal.h
index 5664417e8d5..57259176096 100644
--- a/dbms/src/Columns/ColumnDecimal.h
+++ b/dbms/src/Columns/ColumnDecimal.h
@@ -14,7 +14,6 @@ namespace DB
 
 namespace ErrorCodes
 {
-    extern const int LOGICAL_ERROR;
 }
 
 /// PaddedPODArray extended by Decimal scale
diff --git a/dbms/src/Columns/ColumnLowCardinality.h b/dbms/src/Columns/ColumnLowCardinality.h
index c69e5fc039d..d7887bb6643 100644
--- a/dbms/src/Columns/ColumnLowCardinality.h
+++ b/dbms/src/Columns/ColumnLowCardinality.h
@@ -12,7 +12,6 @@ namespace DB
 
 namespace ErrorCodes
 {
-    extern const int ILLEGAL_COLUMN;
 }
 
 class ColumnLowCardinality final : public COWHelper<IColumn, ColumnLowCardinality>
diff --git a/dbms/src/Columns/IColumn.h b/dbms/src/Columns/IColumn.h
index 7478083ff70..208fca7f6fc 100644
--- a/dbms/src/Columns/IColumn.h
+++ b/dbms/src/Columns/IColumn.h
@@ -18,7 +18,6 @@ namespace ErrorCodes
 {
     extern const int CANNOT_GET_SIZE_OF_FIELD;
     extern const int NOT_IMPLEMENTED;
-    extern const int SIZES_OF_COLUMNS_DOESNT_MATCH;
 }
 
 class Arena;
diff --git a/dbms/src/Common/Exception.cpp b/dbms/src/Common/Exception.cpp
index 0ca4587aa6a..560fe6ed4f8 100644
--- a/dbms/src/Common/Exception.cpp
+++ b/dbms/src/Common/Exception.cpp
@@ -21,8 +21,6 @@ namespace ErrorCodes
     extern const int POCO_EXCEPTION;
     extern const int STD_EXCEPTION;
     extern const int UNKNOWN_EXCEPTION;
-    extern const int CANNOT_TRUNCATE_FILE;
-    extern const int NOT_IMPLEMENTED;
     extern const int LOGICAL_ERROR;
 }
 
diff --git a/dbms/src/Common/Exception.h b/dbms/src/Common/Exception.h
index fc0a4e565e6..19a0cbda0f7 100644
--- a/dbms/src/Common/Exception.h
+++ b/dbms/src/Common/Exception.h
@@ -16,7 +16,6 @@ namespace DB
 
 namespace ErrorCodes
 {
-    extern const int POCO_EXCEPTION;
 }
 
 class Exception : public Poco::Exception
diff --git a/dbms/src/Common/TaskStatsInfoGetter.cpp b/dbms/src/Common/TaskStatsInfoGetter.cpp
index 85ed837e4ad..2046850d483 100644
--- a/dbms/src/Common/TaskStatsInfoGetter.cpp
+++ b/dbms/src/Common/TaskStatsInfoGetter.cpp
@@ -30,7 +30,6 @@ namespace DB
 namespace ErrorCodes
 {
     extern const int NETLINK_ERROR;
-    extern const int LOGICAL_ERROR;
 }
 
 // Replace NLMSG_OK with explicit casts since that system macro contains signedness bugs which are not going to be fixed.
diff --git a/dbms/src/Common/ThreadStatus.cpp b/dbms/src/Common/ThreadStatus.cpp
index a76a558da20..9bed96552ea 100644
--- a/dbms/src/Common/ThreadStatus.cpp
+++ b/dbms/src/Common/ThreadStatus.cpp
@@ -18,7 +18,6 @@ namespace DB
 namespace ErrorCodes
 {
     extern const int LOGICAL_ERROR;
-    extern const int PTHREAD_ERROR;
 }
 
 
diff --git a/dbms/src/Common/TraceCollector.cpp b/dbms/src/Common/TraceCollector.cpp
index 56493d46ee5..dd9ed091815 100644
--- a/dbms/src/Common/TraceCollector.cpp
+++ b/dbms/src/Common/TraceCollector.cpp
@@ -36,8 +36,6 @@ namespace
 
 namespace ErrorCodes
 {
-    extern const int NULL_POINTER_DEREFERENCE;
-    extern const int THREAD_IS_NOT_JOINABLE;
 }
 
 TraceCollector::TraceCollector()
diff --git a/dbms/src/Common/XDBCBridgeHelper.h b/dbms/src/Common/XDBCBridgeHelper.h
index c8ecb30ec68..613d1bed8d7 100644
--- a/dbms/src/Common/XDBCBridgeHelper.h
+++ b/dbms/src/Common/XDBCBridgeHelper.h
@@ -20,7 +20,6 @@ namespace DB
 {
 namespace ErrorCodes
 {
-    extern const int EXTERNAL_EXECUTABLE_NOT_FOUND;
     extern const int EXTERNAL_SERVER_IS_NOT_RESPONDING;
     extern const int ILLEGAL_TYPE_OF_ARGUMENT;
 }
diff --git a/dbms/src/Common/ZooKeeper/ZooKeeperNodeCache.h b/dbms/src/Common/ZooKeeper/ZooKeeperNodeCache.h
index 8bdb55e6ebd..c8e7cc9775d 100644
--- a/dbms/src/Common/ZooKeeper/ZooKeeperNodeCache.h
+++ b/dbms/src/Common/ZooKeeper/ZooKeeperNodeCache.h
@@ -13,7 +13,6 @@ namespace DB
 {
     namespace ErrorCodes
     {
-        extern const int NO_ZOOKEEPER;
     }
 }
 
diff --git a/dbms/src/Common/getNumberOfPhysicalCPUCores.cpp b/dbms/src/Common/getNumberOfPhysicalCPUCores.cpp
index 98c2f88bd6a..10c2e082aaa 100644
--- a/dbms/src/Common/getNumberOfPhysicalCPUCores.cpp
+++ b/dbms/src/Common/getNumberOfPhysicalCPUCores.cpp
@@ -5,7 +5,6 @@
 #if USE_CPUID
 #   include <libcpuid/libcpuid.h>
 #   include <Common/Exception.h>
-    namespace DB { namespace ErrorCodes { extern const int CPUID_ERROR; }}
 #elif USE_CPUINFO
 #   include <cpuinfo.h>
 #endif
diff --git a/dbms/src/Common/parseRemoteDescription.cpp b/dbms/src/Common/parseRemoteDescription.cpp
index 7c41ac6e38b..b69fc61783e 100644
--- a/dbms/src/Common/parseRemoteDescription.cpp
+++ b/dbms/src/Common/parseRemoteDescription.cpp
@@ -7,7 +7,6 @@ namespace DB
 
 namespace ErrorCodes
 {
-    extern const int NUMBER_OF_ARGUMENTS_DOESNT_MATCH;
     extern const int BAD_ARGUMENTS;
 }
 
diff --git a/dbms/src/Compression/CompressedReadBufferBase.cpp b/dbms/src/Compression/CompressedReadBufferBase.cpp
index c85f9768736..1cc22c4f5af 100644
--- a/dbms/src/Compression/CompressedReadBufferBase.cpp
+++ b/dbms/src/Compression/CompressedReadBufferBase.cpp
@@ -28,7 +28,6 @@ namespace DB
 
 namespace ErrorCodes
 {
-    extern const int UNKNOWN_COMPRESSION_METHOD;
     extern const int TOO_LARGE_SIZE_COMPRESSED;
     extern const int CHECKSUM_DOESNT_MATCH;
     extern const int CANNOT_DECOMPRESS;
diff --git a/dbms/src/Compression/CompressedWriteBuffer.cpp b/dbms/src/Compression/CompressedWriteBuffer.cpp
index 9dd3c23100f..1161298d6d5 100644
--- a/dbms/src/Compression/CompressedWriteBuffer.cpp
+++ b/dbms/src/Compression/CompressedWriteBuffer.cpp
@@ -14,8 +14,6 @@ namespace DB
 
 namespace ErrorCodes
 {
-    extern const int CANNOT_COMPRESS;
-    extern const int UNKNOWN_COMPRESSION_METHOD;
 }
 
 static constexpr auto CHECKSUM_SIZE{sizeof(CityHash_v1_0_2::uint128)};
diff --git a/dbms/src/Compression/CompressionCodecGorilla.cpp b/dbms/src/Compression/CompressionCodecGorilla.cpp
index ba8e9c4e37b..ab1d9614d99 100644
--- a/dbms/src/Compression/CompressionCodecGorilla.cpp
+++ b/dbms/src/Compression/CompressionCodecGorilla.cpp
@@ -21,8 +21,6 @@ namespace ErrorCodes
 {
 extern const int CANNOT_COMPRESS;
 extern const int CANNOT_DECOMPRESS;
-extern const int ILLEGAL_SYNTAX_FOR_CODEC_TYPE;
-extern const int ILLEGAL_CODEC_PARAMETER;
 }
 
 namespace
diff --git a/dbms/src/Compression/CompressionCodecLZ4.cpp b/dbms/src/Compression/CompressionCodecLZ4.cpp
index 450ca7b335a..cf8f8e976ea 100644
--- a/dbms/src/Compression/CompressionCodecLZ4.cpp
+++ b/dbms/src/Compression/CompressionCodecLZ4.cpp
@@ -19,7 +19,6 @@ namespace ErrorCodes
 {
 extern const int CANNOT_COMPRESS;
 extern const int ILLEGAL_SYNTAX_FOR_CODEC_TYPE;
-extern const int ILLEGAL_CODEC_PARAMETER;
 }
 
 
diff --git a/dbms/src/Compression/CompressionCodecMultiple.cpp b/dbms/src/Compression/CompressionCodecMultiple.cpp
index c6a009eede4..4f5d45606c2 100644
--- a/dbms/src/Compression/CompressionCodecMultiple.cpp
+++ b/dbms/src/Compression/CompressionCodecMultiple.cpp
@@ -17,7 +17,6 @@ namespace DB
 
 namespace ErrorCodes
 {
-extern const int UNKNOWN_CODEC;
 extern const int CORRUPTED_DATA;
 }
 
diff --git a/dbms/src/Core/SettingsCollection.cpp b/dbms/src/Core/SettingsCollection.cpp
index 9edfddb435d..6e5a863e4d5 100644
--- a/dbms/src/Core/SettingsCollection.cpp
+++ b/dbms/src/Core/SettingsCollection.cpp
@@ -14,16 +14,11 @@ namespace DB
 {
 namespace ErrorCodes
 {
-    extern const int TYPE_MISMATCH;
     extern const int UNKNOWN_LOAD_BALANCING;
     extern const int UNKNOWN_OVERFLOW_MODE;
-    extern const int ILLEGAL_OVERFLOW_MODE;
     extern const int UNKNOWN_TOTALS_MODE;
-    extern const int UNKNOWN_COMPRESSION_METHOD;
     extern const int UNKNOWN_DISTRIBUTED_PRODUCT_MODE;
-    extern const int UNKNOWN_GLOBAL_SUBQUERIES_METHOD;
     extern const int UNKNOWN_JOIN;
-    extern const int UNKNOWN_LOG_LEVEL;
     extern const int SIZE_OF_FIXED_STRING_DOESNT_MATCH;
     extern const int BAD_ARGUMENTS;
     extern const int UNKNOWN_SETTING;
diff --git a/dbms/src/DataStreams/ColumnGathererStream.cpp b/dbms/src/DataStreams/ColumnGathererStream.cpp
index c7dd5c86509..6115de8c1ab 100644
--- a/dbms/src/DataStreams/ColumnGathererStream.cpp
+++ b/dbms/src/DataStreams/ColumnGathererStream.cpp
@@ -10,10 +10,8 @@ namespace DB
 
 namespace ErrorCodes
 {
-    extern const int LOGICAL_ERROR;
     extern const int INCOMPATIBLE_COLUMNS;
     extern const int INCORRECT_NUMBER_OF_COLUMNS;
-    extern const int NOT_FOUND_COLUMN_IN_BLOCK;
     extern const int EMPTY_DATA_PASSED;
     extern const int RECEIVED_EMPTY_DATA;
 }
diff --git a/dbms/src/DataStreams/FilterBlockInputStream.cpp b/dbms/src/DataStreams/FilterBlockInputStream.cpp
index 6516af786f3..43ee0faa09e 100644
--- a/dbms/src/DataStreams/FilterBlockInputStream.cpp
+++ b/dbms/src/DataStreams/FilterBlockInputStream.cpp
@@ -13,7 +13,6 @@ namespace DB
 
 namespace ErrorCodes
 {
-    extern const int ILLEGAL_TYPE_OF_COLUMN_FOR_FILTER;
 }
 
 
diff --git a/dbms/src/DataStreams/GraphiteRollupSortedBlockInputStream.cpp b/dbms/src/DataStreams/GraphiteRollupSortedBlockInputStream.cpp
index 64a0d52c1aa..64fc0ca2b83 100644
--- a/dbms/src/DataStreams/GraphiteRollupSortedBlockInputStream.cpp
+++ b/dbms/src/DataStreams/GraphiteRollupSortedBlockInputStream.cpp
@@ -7,7 +7,6 @@ namespace DB
 
 namespace ErrorCodes
 {
-    extern const int NO_SUCH_COLUMN_IN_TABLE;
     extern const int LOGICAL_ERROR;
 }
 
diff --git a/dbms/src/DataStreams/IBlockInputStream.cpp b/dbms/src/DataStreams/IBlockInputStream.cpp
index c894bcdf381..12bcec5310b 100644
--- a/dbms/src/DataStreams/IBlockInputStream.cpp
+++ b/dbms/src/DataStreams/IBlockInputStream.cpp
@@ -20,10 +20,7 @@ namespace ErrorCodes
     extern const int TOO_MANY_ROWS;
     extern const int TOO_MANY_BYTES;
     extern const int TOO_MANY_ROWS_OR_BYTES;
-    extern const int TIMEOUT_EXCEEDED;
-    extern const int TOO_SLOW;
     extern const int LOGICAL_ERROR;
-    extern const int BLOCKS_HAVE_DIFFERENT_STRUCTURE;
     extern const int TOO_DEEP_PIPELINE;
 }
 
diff --git a/dbms/src/DataStreams/IBlockInputStream.h b/dbms/src/DataStreams/IBlockInputStream.h
index c4582abd0a9..6fe8be079d8 100644
--- a/dbms/src/DataStreams/IBlockInputStream.h
+++ b/dbms/src/DataStreams/IBlockInputStream.h
@@ -18,8 +18,6 @@ namespace DB
 
 namespace ErrorCodes
 {
-    extern const int OUTPUT_IS_NOT_SORTED;
-    extern const int QUERY_WAS_CANCELLED;
 }
 
 class ProcessListElement;
diff --git a/dbms/src/DataStreams/MergeSortingBlockInputStream.h b/dbms/src/DataStreams/MergeSortingBlockInputStream.h
index 5b157310765..b4b9aafdddf 100644
--- a/dbms/src/DataStreams/MergeSortingBlockInputStream.h
+++ b/dbms/src/DataStreams/MergeSortingBlockInputStream.h
@@ -23,7 +23,6 @@ using VolumePtr = std::shared_ptr<Volume>;
 
 namespace ErrorCodes
 {
-    extern const int NOT_ENOUGH_SPACE;
 }
 /** Merges stream of sorted each-separately blocks to sorted as-a-whole stream of blocks.
   * If data to sort is too much, could use external sorting, with temporary files.
diff --git a/dbms/src/DataStreams/MergingSortedBlockInputStream.cpp b/dbms/src/DataStreams/MergingSortedBlockInputStream.cpp
index 3614d9c1d66..0b8c20abe5e 100644
--- a/dbms/src/DataStreams/MergingSortedBlockInputStream.cpp
+++ b/dbms/src/DataStreams/MergingSortedBlockInputStream.cpp
@@ -12,7 +12,6 @@ namespace DB
 namespace ErrorCodes
 {
     extern const int LOGICAL_ERROR;
-    extern const int NUMBER_OF_COLUMNS_DOESNT_MATCH;
 }
 
 
diff --git a/dbms/src/DataStreams/NativeBlockInputStream.cpp b/dbms/src/DataStreams/NativeBlockInputStream.cpp
index 31c4095e07f..ae2d6886fa8 100644
--- a/dbms/src/DataStreams/NativeBlockInputStream.cpp
+++ b/dbms/src/DataStreams/NativeBlockInputStream.cpp
@@ -20,7 +20,6 @@ namespace ErrorCodes
     extern const int INCORRECT_INDEX;
     extern const int LOGICAL_ERROR;
     extern const int CANNOT_READ_ALL_DATA;
-    extern const int NOT_IMPLEMENTED;
 }
 
 
diff --git a/dbms/src/DataStreams/RemoteBlockInputStream.cpp b/dbms/src/DataStreams/RemoteBlockInputStream.cpp
index c3af46e49cd..50392692461 100644
--- a/dbms/src/DataStreams/RemoteBlockInputStream.cpp
+++ b/dbms/src/DataStreams/RemoteBlockInputStream.cpp
@@ -21,7 +21,6 @@ namespace DB
 namespace ErrorCodes
 {
     extern const int UNKNOWN_PACKET_FROM_SERVER;
-    extern const int LOGICAL_ERROR;
 }
 
 
diff --git a/dbms/src/DataStreams/RemoteBlockOutputStream.cpp b/dbms/src/DataStreams/RemoteBlockOutputStream.cpp
index 3446af8b840..400ed42fdcb 100644
--- a/dbms/src/DataStreams/RemoteBlockOutputStream.cpp
+++ b/dbms/src/DataStreams/RemoteBlockOutputStream.cpp
@@ -15,7 +15,6 @@ namespace DB
 namespace ErrorCodes
 {
     extern const int UNEXPECTED_PACKET_FROM_SERVER;
-    extern const int LOGICAL_ERROR;
 }
 
 
diff --git a/dbms/src/DataStreams/SummingSortedBlockInputStream.h b/dbms/src/DataStreams/SummingSortedBlockInputStream.h
index fc02d36d3fd..005ef5cb751 100644
--- a/dbms/src/DataStreams/SummingSortedBlockInputStream.h
+++ b/dbms/src/DataStreams/SummingSortedBlockInputStream.h
@@ -15,7 +15,6 @@ namespace DB
 
 namespace ErrorCodes
 {
-    extern const int LOGICAL_ERROR;
 }
 
 
diff --git a/dbms/src/DataStreams/VersionedCollapsingSortedBlockInputStream.cpp b/dbms/src/DataStreams/VersionedCollapsingSortedBlockInputStream.cpp
index de6f7027243..96895ce3a11 100644
--- a/dbms/src/DataStreams/VersionedCollapsingSortedBlockInputStream.cpp
+++ b/dbms/src/DataStreams/VersionedCollapsingSortedBlockInputStream.cpp
@@ -9,7 +9,6 @@ namespace DB
 
 namespace ErrorCodes
 {
-    extern const int LOGICAL_ERROR;
     extern const int NOT_IMPLEMENTED;
 }
 
diff --git a/dbms/src/DataTypes/DataTypeAggregateFunction.cpp b/dbms/src/DataTypes/DataTypeAggregateFunction.cpp
index 8111b1de2fe..ca43d462d45 100644
--- a/dbms/src/DataTypes/DataTypeAggregateFunction.cpp
+++ b/dbms/src/DataTypes/DataTypeAggregateFunction.cpp
@@ -31,7 +31,6 @@ namespace ErrorCodes
     extern const int PARAMETERS_TO_AGGREGATE_FUNCTIONS_MUST_BE_LITERALS;
     extern const int NUMBER_OF_ARGUMENTS_DOESNT_MATCH;
     extern const int LOGICAL_ERROR;
-    extern const int NOT_IMPLEMENTED;
 }
 
 
diff --git a/dbms/src/DataTypes/DataTypeCustomIPv4AndIPv6.cpp b/dbms/src/DataTypes/DataTypeCustomIPv4AndIPv6.cpp
index 60905a4c4b1..5c62e060669 100644
--- a/dbms/src/DataTypes/DataTypeCustomIPv4AndIPv6.cpp
+++ b/dbms/src/DataTypes/DataTypeCustomIPv4AndIPv6.cpp
@@ -13,7 +13,6 @@ namespace DB
 namespace ErrorCodes
 {
     extern const int ILLEGAL_COLUMN;
-    extern const int UNSUPPORTED_METHOD;
     extern const int CANNOT_PARSE_DOMAIN_VALUE_FROM_STRING;
 }
 
diff --git a/dbms/src/DataTypes/DataTypeDecimalBase.cpp b/dbms/src/DataTypes/DataTypeDecimalBase.cpp
index 7b9a391427c..fb5179e26c0 100644
--- a/dbms/src/DataTypes/DataTypeDecimalBase.cpp
+++ b/dbms/src/DataTypes/DataTypeDecimalBase.cpp
@@ -20,9 +20,6 @@ namespace DB
 
 namespace ErrorCodes
 {
-    extern const int NUMBER_OF_ARGUMENTS_DOESNT_MATCH;
-    extern const int ILLEGAL_TYPE_OF_ARGUMENT;
-    extern const int ARGUMENT_OUT_OF_BOUND;
 }
 
 
diff --git a/dbms/src/DataTypes/DataTypeDecimalBase.h b/dbms/src/DataTypes/DataTypeDecimalBase.h
index 11f7490e80a..e62f593ba79 100644
--- a/dbms/src/DataTypes/DataTypeDecimalBase.h
+++ b/dbms/src/DataTypes/DataTypeDecimalBase.h
@@ -17,8 +17,6 @@ namespace DB
 namespace ErrorCodes
 {
     extern const int ARGUMENT_OUT_OF_BOUND;
-    extern const int CANNOT_CONVERT_TYPE;
-    extern const int DECIMAL_OVERFLOW;
 }
 
 class Context;
diff --git a/dbms/src/DataTypes/DataTypesDecimal.cpp b/dbms/src/DataTypes/DataTypesDecimal.cpp
index e62588df857..6fc4a0ecc9f 100644
--- a/dbms/src/DataTypes/DataTypesDecimal.cpp
+++ b/dbms/src/DataTypes/DataTypesDecimal.cpp
@@ -24,7 +24,6 @@ namespace ErrorCodes
 {
     extern const int NUMBER_OF_ARGUMENTS_DOESNT_MATCH;
     extern const int ILLEGAL_TYPE_OF_ARGUMENT;
-    extern const int ARGUMENT_OUT_OF_BOUND;
 }
 
 //
diff --git a/dbms/src/DataTypes/DataTypesDecimal.h b/dbms/src/DataTypes/DataTypesDecimal.h
index 44a008bdc66..447d5e5a291 100644
--- a/dbms/src/DataTypes/DataTypesDecimal.h
+++ b/dbms/src/DataTypes/DataTypesDecimal.h
@@ -11,8 +11,6 @@ namespace DB
 
 namespace ErrorCodes
 {
-    extern const int ARGUMENT_OUT_OF_BOUND;
-    extern const int CANNOT_CONVERT_TYPE;
     extern const int DECIMAL_OVERFLOW;
 }
 
diff --git a/dbms/src/DataTypes/getLeastSupertype.cpp b/dbms/src/DataTypes/getLeastSupertype.cpp
index d45c9872394..cfe88987c2d 100644
--- a/dbms/src/DataTypes/getLeastSupertype.cpp
+++ b/dbms/src/DataTypes/getLeastSupertype.cpp
@@ -22,7 +22,6 @@ namespace DB
 
 namespace ErrorCodes
 {
-    extern const int BAD_ARGUMENTS;
     extern const int NO_COMMON_TYPE;
 }
 
diff --git a/dbms/src/DataTypes/getMostSubtype.cpp b/dbms/src/DataTypes/getMostSubtype.cpp
index 8fb96f5d366..aebc0729088 100644
--- a/dbms/src/DataTypes/getMostSubtype.cpp
+++ b/dbms/src/DataTypes/getMostSubtype.cpp
@@ -18,7 +18,6 @@ namespace DB
 
 namespace ErrorCodes
 {
-extern const int BAD_ARGUMENTS;
 extern const int NO_COMMON_TYPE;
 }
 
diff --git a/dbms/src/Databases/DatabaseDictionary.cpp b/dbms/src/Databases/DatabaseDictionary.cpp
index 9323a5914f1..9bf36005af1 100644
--- a/dbms/src/Databases/DatabaseDictionary.cpp
+++ b/dbms/src/Databases/DatabaseDictionary.cpp
@@ -14,12 +14,7 @@ namespace DB
 {
 namespace ErrorCodes
 {
-    extern const int TABLE_ALREADY_EXISTS;
-    extern const int UNKNOWN_TABLE;
-    extern const int LOGICAL_ERROR;
-    extern const int CANNOT_GET_CREATE_TABLE_QUERY;
     extern const int SYNTAX_ERROR;
-    extern const int UNSUPPORTED_METHOD;
 }
 
 DatabaseDictionary::DatabaseDictionary(const String & name_)
diff --git a/dbms/src/Databases/DatabaseMySQL.cpp b/dbms/src/Databases/DatabaseMySQL.cpp
index db4ef926822..d0238865bf6 100644
--- a/dbms/src/Databases/DatabaseMySQL.cpp
+++ b/dbms/src/Databases/DatabaseMySQL.cpp
@@ -33,7 +33,6 @@ namespace ErrorCodes
 {
     extern const int UNKNOWN_TABLE;
     extern const int TABLE_IS_DROPPED;
-    extern const int TABLE_WAS_NOT_DROPPED;
     extern const int TABLE_ALREADY_EXISTS;
     extern const int UNEXPECTED_AST_STRUCTURE;
 }
diff --git a/dbms/src/Databases/DatabaseOrdinary.cpp b/dbms/src/Databases/DatabaseOrdinary.cpp
index 2188b7b5e80..9256466de75 100644
--- a/dbms/src/Databases/DatabaseOrdinary.cpp
+++ b/dbms/src/Databases/DatabaseOrdinary.cpp
@@ -36,9 +36,6 @@ namespace DB
 
 namespace ErrorCodes
 {
-    extern const int CANNOT_CREATE_DICTIONARY_FROM_METADATA;
-    extern const int EMPTY_LIST_OF_COLUMNS_PASSED;
-    extern const int CANNOT_PARSE_TEXT;
 }
 
 
diff --git a/dbms/src/Databases/DatabaseWithDictionaries.cpp b/dbms/src/Databases/DatabaseWithDictionaries.cpp
index 3559067da0f..98ea060e599 100644
--- a/dbms/src/Databases/DatabaseWithDictionaries.cpp
+++ b/dbms/src/Databases/DatabaseWithDictionaries.cpp
@@ -15,10 +15,8 @@ namespace DB
 
 namespace ErrorCodes
 {
-    extern const int EMPTY_LIST_OF_COLUMNS_PASSED;
     extern const int TABLE_ALREADY_EXISTS;
     extern const int UNKNOWN_TABLE;
-    extern const int LOGICAL_ERROR;
     extern const int DICTIONARY_ALREADY_EXISTS;
 }
 
diff --git a/dbms/src/Databases/DatabasesCommon.cpp b/dbms/src/Databases/DatabasesCommon.cpp
index becdad672a1..b48c3853715 100644
--- a/dbms/src/Databases/DatabasesCommon.cpp
+++ b/dbms/src/Databases/DatabasesCommon.cpp
@@ -13,11 +13,8 @@ namespace DB
 
 namespace ErrorCodes
 {
-    extern const int EMPTY_LIST_OF_COLUMNS_PASSED;
     extern const int TABLE_ALREADY_EXISTS;
     extern const int UNKNOWN_TABLE;
-    extern const int LOGICAL_ERROR;
-    extern const int DICTIONARY_ALREADY_EXISTS;
 }
 
 DatabaseWithOwnTablesBase::DatabaseWithOwnTablesBase(const String & name_, const String & logger)
diff --git a/dbms/src/Dictionaries/CacheDictionary.cpp b/dbms/src/Dictionaries/CacheDictionary.cpp
index bb793d7fb5e..8c8fddef715 100644
--- a/dbms/src/Dictionaries/CacheDictionary.cpp
+++ b/dbms/src/Dictionaries/CacheDictionary.cpp
@@ -44,7 +44,6 @@ namespace ErrorCodes
     extern const int TYPE_MISMATCH;
     extern const int BAD_ARGUMENTS;
     extern const int UNSUPPORTED_METHOD;
-    extern const int LOGICAL_ERROR;
     extern const int TOO_SMALL_BUFFER_SIZE;
 }
 
diff --git a/dbms/src/Dictionaries/CacheDictionary.h b/dbms/src/Dictionaries/CacheDictionary.h
index a32cbfa0f4c..a0ec80a58ed 100644
--- a/dbms/src/Dictionaries/CacheDictionary.h
+++ b/dbms/src/Dictionaries/CacheDictionary.h
@@ -28,7 +28,6 @@ namespace DB
 
 namespace ErrorCodes
 {
-    extern const int CACHE_DICTIONARY_UPDATE_FAIL;
 }
 
 /*
diff --git a/dbms/src/Dictionaries/CacheDictionary.inc.h b/dbms/src/Dictionaries/CacheDictionary.inc.h
index a043e884880..7b108438f76 100644
--- a/dbms/src/Dictionaries/CacheDictionary.inc.h
+++ b/dbms/src/Dictionaries/CacheDictionary.inc.h
@@ -32,7 +32,6 @@ namespace DB
 {
 namespace ErrorCodes
 {
-    extern const int TYPE_MISMATCH;
 }
 
 template <typename AttributeType, typename OutputType, typename DefaultGetter>
diff --git a/dbms/src/Dictionaries/ClickHouseDictionarySource.cpp b/dbms/src/Dictionaries/ClickHouseDictionarySource.cpp
index dc4b687c8dc..97ae125abbb 100644
--- a/dbms/src/Dictionaries/ClickHouseDictionarySource.cpp
+++ b/dbms/src/Dictionaries/ClickHouseDictionarySource.cpp
@@ -18,7 +18,6 @@ namespace DB
 {
 namespace ErrorCodes
 {
-    extern const int UNSUPPORTED_METHOD;
 }
 
 
diff --git a/dbms/src/Dictionaries/ComplexKeyHashedDictionary.cpp b/dbms/src/Dictionaries/ComplexKeyHashedDictionary.cpp
index 7d8d481e2fa..485b0937be3 100644
--- a/dbms/src/Dictionaries/ComplexKeyHashedDictionary.cpp
+++ b/dbms/src/Dictionaries/ComplexKeyHashedDictionary.cpp
@@ -9,7 +9,6 @@ namespace DB
 namespace ErrorCodes
 {
     extern const int TYPE_MISMATCH;
-    extern const int ARGUMENT_OUT_OF_BOUND;
     extern const int BAD_ARGUMENTS;
     extern const int DICTIONARY_IS_EMPTY;
 }
diff --git a/dbms/src/Dictionaries/DictionarySourceFactory.cpp b/dbms/src/Dictionaries/DictionarySourceFactory.cpp
index a8885d95ad3..fa3b3017ad2 100644
--- a/dbms/src/Dictionaries/DictionarySourceFactory.cpp
+++ b/dbms/src/Dictionaries/DictionarySourceFactory.cpp
@@ -16,7 +16,6 @@ namespace ErrorCodes
     extern const int UNKNOWN_ELEMENT_IN_CONFIG;
     extern const int EXCESSIVE_ELEMENT_IN_CONFIG;
     extern const int LOGICAL_ERROR;
-    extern const int SUPPORT_IS_DISABLED;
 }
 
 namespace
diff --git a/dbms/src/Dictionaries/ExternalQueryBuilder.cpp b/dbms/src/Dictionaries/ExternalQueryBuilder.cpp
index 868b01c7c2c..529fb3d60fa 100644
--- a/dbms/src/Dictionaries/ExternalQueryBuilder.cpp
+++ b/dbms/src/Dictionaries/ExternalQueryBuilder.cpp
@@ -13,7 +13,6 @@ namespace DB
 namespace ErrorCodes
 {
     extern const int UNSUPPORTED_METHOD;
-    extern const int LOGICAL_ERROR;
 }
 
 
diff --git a/dbms/src/Dictionaries/FlatDictionary.cpp b/dbms/src/Dictionaries/FlatDictionary.cpp
index a26d566e10c..8a0e4175d01 100644
--- a/dbms/src/Dictionaries/FlatDictionary.cpp
+++ b/dbms/src/Dictionaries/FlatDictionary.cpp
@@ -11,8 +11,6 @@ namespace ErrorCodes
     extern const int ARGUMENT_OUT_OF_BOUND;
     extern const int BAD_ARGUMENTS;
     extern const int DICTIONARY_IS_EMPTY;
-    extern const int LOGICAL_ERROR;
-    extern const int UNKNOWN_TYPE;
     extern const int UNSUPPORTED_METHOD;
 }
 
diff --git a/dbms/src/Dictionaries/HashedDictionary.cpp b/dbms/src/Dictionaries/HashedDictionary.cpp
index 025e2e040b9..a7244e05fae 100644
--- a/dbms/src/Dictionaries/HashedDictionary.cpp
+++ b/dbms/src/Dictionaries/HashedDictionary.cpp
@@ -23,7 +23,6 @@ namespace DB
 namespace ErrorCodes
 {
     extern const int TYPE_MISMATCH;
-    extern const int ARGUMENT_OUT_OF_BOUND;
     extern const int BAD_ARGUMENTS;
     extern const int DICTIONARY_IS_EMPTY;
     extern const int UNSUPPORTED_METHOD;
diff --git a/dbms/src/Dictionaries/LibraryDictionarySource.cpp b/dbms/src/Dictionaries/LibraryDictionarySource.cpp
index 945348d883b..a4b4be79485 100644
--- a/dbms/src/Dictionaries/LibraryDictionarySource.cpp
+++ b/dbms/src/Dictionaries/LibraryDictionarySource.cpp
@@ -16,7 +16,6 @@ namespace DB
 {
 namespace ErrorCodes
 {
-    extern const int NOT_IMPLEMENTED;
     extern const int SIZES_OF_COLUMNS_DOESNT_MATCH;
     extern const int FILE_DOESNT_EXIST;
     extern const int EXTERNAL_LIBRARY_ERROR;
diff --git a/dbms/src/Dictionaries/MongoDBDictionarySource.cpp b/dbms/src/Dictionaries/MongoDBDictionarySource.cpp
index 97391a1ee59..14d902ba404 100644
--- a/dbms/src/Dictionaries/MongoDBDictionarySource.cpp
+++ b/dbms/src/Dictionaries/MongoDBDictionarySource.cpp
@@ -60,7 +60,6 @@ namespace DB
 namespace ErrorCodes
 {
     extern const int UNSUPPORTED_METHOD;
-    extern const int WRONG_PASSWORD;
     extern const int MONGODB_CANNOT_AUTHENTICATE;
 }
 
diff --git a/dbms/src/Dictionaries/TrieDictionary.cpp b/dbms/src/Dictionaries/TrieDictionary.cpp
index 2d9cfd71cee..7ce590139f0 100644
--- a/dbms/src/Dictionaries/TrieDictionary.cpp
+++ b/dbms/src/Dictionaries/TrieDictionary.cpp
@@ -28,7 +28,6 @@ namespace DB
 namespace ErrorCodes
 {
     extern const int TYPE_MISMATCH;
-    extern const int ARGUMENT_OUT_OF_BOUND;
     extern const int BAD_ARGUMENTS;
     extern const int DICTIONARY_IS_EMPTY;
     extern const int NOT_IMPLEMENTED;
diff --git a/dbms/src/Disks/DiskMemory.cpp b/dbms/src/Disks/DiskMemory.cpp
index ba487535464..fff1f072cd4 100644
--- a/dbms/src/Disks/DiskMemory.cpp
+++ b/dbms/src/Disks/DiskMemory.cpp
@@ -16,8 +16,6 @@ namespace ErrorCodes
     extern const int FILE_ALREADY_EXISTS;
     extern const int DIRECTORY_DOESNT_EXIST;
     extern const int CANNOT_DELETE_DIRECTORY;
-    extern const int CANNOT_SEEK_THROUGH_FILE;
-    extern const int SEEK_POSITION_OUT_OF_BOUND;
 }
 
 
diff --git a/dbms/src/Disks/DiskS3.cpp b/dbms/src/Disks/DiskS3.cpp
index f5a7517e7c6..3a4d6fbdf95 100644
--- a/dbms/src/Disks/DiskS3.cpp
+++ b/dbms/src/Disks/DiskS3.cpp
@@ -26,7 +26,6 @@ namespace DB
 namespace ErrorCodes
 {
     extern const int FILE_ALREADY_EXISTS;
-    extern const int FILE_DOESNT_EXIST;
     extern const int PATH_ACCESS_DENIED;
     extern const int SEEK_POSITION_OUT_OF_BOUND;
     extern const int CANNOT_SEEK_THROUGH_FILE;
diff --git a/dbms/src/Disks/DiskSpaceMonitor.h b/dbms/src/Disks/DiskSpaceMonitor.h
index cb00944e149..423e73286cb 100644
--- a/dbms/src/Disks/DiskSpaceMonitor.h
+++ b/dbms/src/Disks/DiskSpaceMonitor.h
@@ -18,14 +18,6 @@ namespace DB
 {
 namespace ErrorCodes
 {
-    extern const int LOGICAL_ERROR;
-    extern const int NOT_ENOUGH_SPACE;
-    extern const int NOT_IMPLEMENTED;
-    extern const int SYSTEM_ERROR;
-    extern const int UNKNOWN_ELEMENT_IN_CONFIG;
-    extern const int EXCESSIVE_ELEMENT_IN_CONFIG;
-    extern const int UNKNOWN_POLICY;
-    extern const int UNKNOWN_DISK;
 }
 
 /// Parse .xml configuration and store information about disks
diff --git a/dbms/src/Functions/FunctionBase64Conversion.h b/dbms/src/Functions/FunctionBase64Conversion.h
index fa1e60cd185..27a873f69fa 100644
--- a/dbms/src/Functions/FunctionBase64Conversion.h
+++ b/dbms/src/Functions/FunctionBase64Conversion.h
@@ -18,7 +18,6 @@ namespace ErrorCodes
 {
     extern const int ILLEGAL_COLUMN;
     extern const int ILLEGAL_TYPE_OF_ARGUMENT;
-    extern const int NUMBER_OF_ARGUMENTS_DOESNT_MATCH;
     extern const int INCORRECT_DATA;
 }
 
diff --git a/dbms/src/Functions/FunctionBinaryArithmetic.h b/dbms/src/Functions/FunctionBinaryArithmetic.h
index 43563e7c6c5..0ab0e77f4eb 100644
--- a/dbms/src/Functions/FunctionBinaryArithmetic.h
+++ b/dbms/src/Functions/FunctionBinaryArithmetic.h
@@ -47,7 +47,6 @@ namespace ErrorCodes
     extern const int LOGICAL_ERROR;
     extern const int DECIMAL_OVERFLOW;
     extern const int CANNOT_ADD_DIFFERENT_AGGREGATE_STATES;
-    extern const int ILLEGAL_DIVISION;
 }
 
 
diff --git a/dbms/src/Functions/FunctionBitTestMany.h b/dbms/src/Functions/FunctionBitTestMany.h
index 87a10946dc4..ea8f5e1bd7c 100644
--- a/dbms/src/Functions/FunctionBitTestMany.h
+++ b/dbms/src/Functions/FunctionBitTestMany.h
@@ -13,7 +13,6 @@ namespace DB
 
 namespace ErrorCodes
 {
-    extern const int ILLEGAL_DIVISION;
     extern const int ILLEGAL_COLUMN;
     extern const int ILLEGAL_TYPE_OF_ARGUMENT;
     extern const int TOO_FEW_ARGUMENTS_FOR_FUNCTION;
diff --git a/dbms/src/Functions/FunctionsBitmap.h b/dbms/src/Functions/FunctionsBitmap.h
index c264b2fb0ba..a43e93e95c0 100644
--- a/dbms/src/Functions/FunctionsBitmap.h
+++ b/dbms/src/Functions/FunctionsBitmap.h
@@ -23,7 +23,6 @@ namespace DB
 namespace ErrorCodes
 {
     extern const int LOGICAL_ERROR;
-    extern const int NUMBER_OF_ARGUMENTS_DOESNT_MATCH;
 }
 
 /** Bitmap functions.
diff --git a/dbms/src/Functions/FunctionsCoding.h b/dbms/src/Functions/FunctionsCoding.h
index 6dd57812c1c..14f2541a3c1 100644
--- a/dbms/src/Functions/FunctionsCoding.h
+++ b/dbms/src/Functions/FunctionsCoding.h
@@ -34,7 +34,6 @@ namespace DB
 
 namespace ErrorCodes
 {
-    extern const int TOO_FEW_ARGUMENTS_FOR_FUNCTION;
     extern const int LOGICAL_ERROR;
     extern const int ILLEGAL_COLUMN;
 }
diff --git a/dbms/src/Functions/FunctionsConsistentHashing.h b/dbms/src/Functions/FunctionsConsistentHashing.h
index f789d9eac53..0ed5b223446 100644
--- a/dbms/src/Functions/FunctionsConsistentHashing.h
+++ b/dbms/src/Functions/FunctionsConsistentHashing.h
@@ -13,9 +13,6 @@ namespace DB
 {
 namespace ErrorCodes
 {
-    extern const int LOGICAL_ERROR;
-    extern const int NUMBER_OF_ARGUMENTS_DOESNT_MATCH;
-    extern const int ILLEGAL_COLUMN;
     extern const int BAD_ARGUMENTS;
 }
 
diff --git a/dbms/src/Functions/FunctionsExternalDictionaries.h b/dbms/src/Functions/FunctionsExternalDictionaries.h
index a2e4b146ea4..10859d83341 100644
--- a/dbms/src/Functions/FunctionsExternalDictionaries.h
+++ b/dbms/src/Functions/FunctionsExternalDictionaries.h
@@ -44,7 +44,6 @@ namespace DB
 
 namespace ErrorCodes
 {
-    extern const int DICTIONARIES_WAS_NOT_LOADED;
     extern const int UNSUPPORTED_METHOD;
     extern const int UNKNOWN_TYPE;
     extern const int NUMBER_OF_ARGUMENTS_DOESNT_MATCH;
diff --git a/dbms/src/Functions/FunctionsStringSimilarity.h b/dbms/src/Functions/FunctionsStringSimilarity.h
index c424a95ee13..1be2e0e61c4 100644
--- a/dbms/src/Functions/FunctionsStringSimilarity.h
+++ b/dbms/src/Functions/FunctionsStringSimilarity.h
@@ -23,7 +23,6 @@ namespace ErrorCodes
 {
     extern const int ILLEGAL_TYPE_OF_ARGUMENT;
     extern const int ILLEGAL_COLUMN;
-    extern const int NUMBER_OF_ARGUMENTS_DOESNT_MATCH;
     extern const int TOO_LARGE_STRING_SIZE;
 }
 
diff --git a/dbms/src/Functions/GeoUtils.cpp b/dbms/src/Functions/GeoUtils.cpp
index e26566b9c0c..488a102e208 100644
--- a/dbms/src/Functions/GeoUtils.cpp
+++ b/dbms/src/Functions/GeoUtils.cpp
@@ -237,7 +237,6 @@ namespace DB
 
 namespace ErrorCodes
 {
-extern const int ARGUMENT_OUT_OF_BOUND;
 }
 
 namespace GeoUtils
diff --git a/dbms/src/Functions/IFunction.h b/dbms/src/Functions/IFunction.h
index fc9eb904f82..3887f3f1669 100644
--- a/dbms/src/Functions/IFunction.h
+++ b/dbms/src/Functions/IFunction.h
@@ -24,9 +24,7 @@ namespace DB
 
 namespace ErrorCodes
 {
-    extern const int ILLEGAL_TYPE_OF_ARGUMENT;
     extern const int NOT_IMPLEMENTED;
-    extern const int LOGICAL_ERROR;
 }
 
 class Field;
diff --git a/dbms/src/Functions/array/arrayCompact.cpp b/dbms/src/Functions/array/arrayCompact.cpp
index 489d18440e0..5b13c8d04b9 100644
--- a/dbms/src/Functions/array/arrayCompact.cpp
+++ b/dbms/src/Functions/array/arrayCompact.cpp
@@ -11,7 +11,6 @@ namespace DB
 /// arrayCompact(['a', 'a', 'b', 'b', 'a']) = ['a', 'b', 'a'] - compact arrays
 namespace ErrorCodes
 {
-    extern const int ILLEGAL_COLUMN;
 }
 
 struct ArrayCompactImpl
diff --git a/dbms/src/Functions/array/arrayEnumerateRanked.h b/dbms/src/Functions/array/arrayEnumerateRanked.h
index 8b87dd2ceb5..3962c927343 100644
--- a/dbms/src/Functions/array/arrayEnumerateRanked.h
+++ b/dbms/src/Functions/array/arrayEnumerateRanked.h
@@ -59,8 +59,6 @@ namespace DB
 namespace ErrorCodes
 {
     extern const int NUMBER_OF_ARGUMENTS_DOESNT_MATCH;
-    extern const int ILLEGAL_COLUMN;
-    extern const int ILLEGAL_TYPE_OF_ARGUMENT;
     extern const int SIZES_OF_ARRAYS_DOESNT_MATCH;
 }
 
diff --git a/dbms/src/Functions/array/arrayResize.cpp b/dbms/src/Functions/array/arrayResize.cpp
index e7cda17cd27..903a39aa4ab 100644
--- a/dbms/src/Functions/array/arrayResize.cpp
+++ b/dbms/src/Functions/array/arrayResize.cpp
@@ -18,7 +18,6 @@ namespace ErrorCodes
 {
     extern const int LOGICAL_ERROR;
     extern const int NUMBER_OF_ARGUMENTS_DOESNT_MATCH;
-    extern const int ILLEGAL_COLUMN;
     extern const int ILLEGAL_TYPE_OF_ARGUMENT;
 }
 
diff --git a/dbms/src/Functions/array/arrayReverse.cpp b/dbms/src/Functions/array/arrayReverse.cpp
index a4f2f1ab90a..9ae165abb42 100644
--- a/dbms/src/Functions/array/arrayReverse.cpp
+++ b/dbms/src/Functions/array/arrayReverse.cpp
@@ -17,7 +17,6 @@ namespace ErrorCodes
 {
     extern const int ILLEGAL_COLUMN;
     extern const int ILLEGAL_TYPE_OF_ARGUMENT;
-    extern const int LOGICAL_ERROR;
 }
 
 
diff --git a/dbms/src/Functions/convertCharset.cpp b/dbms/src/Functions/convertCharset.cpp
index 2b1b17ea4eb..6c6cc99e063 100644
--- a/dbms/src/Functions/convertCharset.cpp
+++ b/dbms/src/Functions/convertCharset.cpp
@@ -22,8 +22,6 @@ namespace DB
 
 namespace ErrorCodes
 {
-    extern const int BAD_ARGUMENTS;
-    extern const int LOGICAL_ERROR;
     extern const int CANNOT_CREATE_CHARSET_CONVERTER;
     extern const int CANNOT_CONVERT_CHARSET;
     extern const int ILLEGAL_COLUMN;
diff --git a/dbms/src/Functions/formatString.h b/dbms/src/Functions/formatString.h
index 3b08d313c4d..69db4aadc2a 100644
--- a/dbms/src/Functions/formatString.h
+++ b/dbms/src/Functions/formatString.h
@@ -17,7 +17,6 @@ namespace DB
 {
 namespace ErrorCodes
 {
-    extern const int LOGICAL_ERROR;
     extern const int BAD_ARGUMENTS;
 }
 
diff --git a/dbms/src/Functions/geoToH3.cpp b/dbms/src/Functions/geoToH3.cpp
index 40c267d8656..24aafacb836 100644
--- a/dbms/src/Functions/geoToH3.cpp
+++ b/dbms/src/Functions/geoToH3.cpp
@@ -17,7 +17,6 @@ namespace DB
 {
 namespace ErrorCodes
 {
-    extern const int ILLEGAL_COLUMN;
 }
 
 /// Implements the function geoToH3 which takes 3 arguments (latitude, longitude and h3 resolution)
diff --git a/dbms/src/Functions/getScalar.cpp b/dbms/src/Functions/getScalar.cpp
index a2ab9623976..d6c0d79557c 100644
--- a/dbms/src/Functions/getScalar.cpp
+++ b/dbms/src/Functions/getScalar.cpp
@@ -14,7 +14,6 @@ namespace DB
 namespace ErrorCodes
 {
     extern const int ILLEGAL_TYPE_OF_ARGUMENT;
-    extern const int ILLEGAL_COLUMN;
 }
 
 /** Get scalar value of sub queries from query context via IAST::Hash.
diff --git a/dbms/src/Functions/neighbor.cpp b/dbms/src/Functions/neighbor.cpp
index c37a3313a80..1080507ced5 100644
--- a/dbms/src/Functions/neighbor.cpp
+++ b/dbms/src/Functions/neighbor.cpp
@@ -10,9 +10,7 @@ namespace DB
 {
 namespace ErrorCodes
 {
-    extern const int ILLEGAL_COLUMN;
     extern const int ILLEGAL_TYPE_OF_ARGUMENT;
-    extern const int ARGUMENT_OUT_OF_BOUND;
     extern const int NUMBER_OF_ARGUMENTS_DOESNT_MATCH;
 }
 
diff --git a/dbms/src/Functions/now64.cpp b/dbms/src/Functions/now64.cpp
index f1a8d444019..873d271e791 100644
--- a/dbms/src/Functions/now64.cpp
+++ b/dbms/src/Functions/now64.cpp
@@ -14,8 +14,6 @@ namespace DB
 
 namespace ErrorCodes
 {
-    extern const int ILLEGAL_COLUMN;
-    extern const int NUMBER_OF_ARGUMENTS_DOESNT_MATCH;
     extern const int CANNOT_CLOCK_GETTIME;
 }
 
diff --git a/dbms/src/Functions/substring.cpp b/dbms/src/Functions/substring.cpp
index 32213d09fd5..c670267d0b6 100644
--- a/dbms/src/Functions/substring.cpp
+++ b/dbms/src/Functions/substring.cpp
@@ -22,7 +22,6 @@ namespace ErrorCodes
 {
     extern const int ILLEGAL_COLUMN;
     extern const int ILLEGAL_TYPE_OF_ARGUMENT;
-    extern const int ARGUMENT_OUT_OF_BOUND;
     extern const int ZERO_ARRAY_OR_TUPLE_INDEX;
     extern const int NUMBER_OF_ARGUMENTS_DOESNT_MATCH;
 }
diff --git a/dbms/src/IO/CascadeWriteBuffer.h b/dbms/src/IO/CascadeWriteBuffer.h
index dc8678ffdd1..db0d1e7a5a8 100644
--- a/dbms/src/IO/CascadeWriteBuffer.h
+++ b/dbms/src/IO/CascadeWriteBuffer.h
@@ -8,7 +8,6 @@ namespace DB
 
 namespace ErrorCodes
 {
-    extern const int CURRENT_WRITE_BUFFER_IS_EXHAUSTED;
 }
 
 /* The buffer is similar to ConcatReadBuffer, but writes data
diff --git a/dbms/src/IO/HTTPCommon.cpp b/dbms/src/IO/HTTPCommon.cpp
index de094cd52cd..e00ef5edf76 100644
--- a/dbms/src/IO/HTTPCommon.cpp
+++ b/dbms/src/IO/HTTPCommon.cpp
@@ -40,7 +40,6 @@ namespace ErrorCodes
     extern const int RECEIVED_ERROR_TOO_MANY_REQUESTS;
     extern const int FEATURE_IS_NOT_ENABLED_AT_BUILD_TIME;
     extern const int UNSUPPORTED_URI_SCHEME;
-    extern const int TOO_MANY_REDIRECTS;
 }
 
 
diff --git a/dbms/src/IO/PeekableReadBuffer.h b/dbms/src/IO/PeekableReadBuffer.h
index f632b4a4b20..49c59c93486 100644
--- a/dbms/src/IO/PeekableReadBuffer.h
+++ b/dbms/src/IO/PeekableReadBuffer.h
@@ -8,7 +8,6 @@ namespace DB
 namespace ErrorCodes
 {
     extern const int LOGICAL_ERROR;
-    extern const int MEMORY_LIMIT_EXCEEDED;
 }
 
 /// Also allows to set checkpoint at some position in stream and come back to this position later.
diff --git a/dbms/src/IO/WriteBufferFromHTTPServerResponse.cpp b/dbms/src/IO/WriteBufferFromHTTPServerResponse.cpp
index 7fbdeab7ab5..77198ca93ea 100644
--- a/dbms/src/IO/WriteBufferFromHTTPServerResponse.cpp
+++ b/dbms/src/IO/WriteBufferFromHTTPServerResponse.cpp
@@ -15,7 +15,6 @@ namespace DB
 
 namespace ErrorCodes
 {
-    extern const int LOGICAL_ERROR;
 }
 
 
diff --git a/dbms/src/IO/WriteBufferFromTemporaryFile.cpp b/dbms/src/IO/WriteBufferFromTemporaryFile.cpp
index 007b8a4283e..f93c79ca587 100644
--- a/dbms/src/IO/WriteBufferFromTemporaryFile.cpp
+++ b/dbms/src/IO/WriteBufferFromTemporaryFile.cpp
@@ -9,7 +9,6 @@ namespace DB
 
 namespace ErrorCodes
 {
-    extern const int CANNOT_OPEN_FILE;
     extern const int CANNOT_SEEK_THROUGH_FILE;
 }
 
diff --git a/dbms/src/IO/ZlibInflatingReadBuffer.h b/dbms/src/IO/ZlibInflatingReadBuffer.h
index 4ba152cdfdc..b8c141e9b9b 100644
--- a/dbms/src/IO/ZlibInflatingReadBuffer.h
+++ b/dbms/src/IO/ZlibInflatingReadBuffer.h
@@ -12,7 +12,6 @@ namespace DB
 
 namespace ErrorCodes
 {
-    extern const int ZLIB_INFLATE_FAILED;
 }
 
 /// Reads compressed data from ReadBuffer in_ and performs decompression using zlib library.
diff --git a/dbms/src/IO/readFloatText.h b/dbms/src/IO/readFloatText.h
index 5e853c1c920..1b9da8db49c 100644
--- a/dbms/src/IO/readFloatText.h
+++ b/dbms/src/IO/readFloatText.h
@@ -97,7 +97,6 @@ namespace DB
 namespace ErrorCodes
 {
     extern const int CANNOT_PARSE_NUMBER;
-    extern const int ARGUMENT_OUT_OF_BOUND;
 }
 
 
diff --git a/dbms/src/Interpreters/Aggregator.h b/dbms/src/Interpreters/Aggregator.h
index cdb1b96f4e8..0fa9bd509bd 100644
--- a/dbms/src/Interpreters/Aggregator.h
+++ b/dbms/src/Interpreters/Aggregator.h
@@ -41,7 +41,6 @@ namespace DB
 namespace ErrorCodes
 {
     extern const int UNKNOWN_AGGREGATED_DATA_VARIANT;
-    extern const int NOT_ENOUGH_SPACE;
 }
 
 class IBlockOutputStream;
diff --git a/dbms/src/Interpreters/AnalyzedJoin.cpp b/dbms/src/Interpreters/AnalyzedJoin.cpp
index b3a14541fa3..f3ab350c373 100644
--- a/dbms/src/Interpreters/AnalyzedJoin.cpp
+++ b/dbms/src/Interpreters/AnalyzedJoin.cpp
@@ -13,8 +13,6 @@ namespace DB
 
 namespace ErrorCodes
 {
-    extern const int LOGICAL_ERROR;
-    extern const int PARAMETER_OUT_OF_BOUND;
 }
 
 AnalyzedJoin::AnalyzedJoin(const Settings & settings, VolumePtr tmp_volume_)
diff --git a/dbms/src/Interpreters/CollectJoinOnKeysVisitor.cpp b/dbms/src/Interpreters/CollectJoinOnKeysVisitor.cpp
index 04484aebe0b..4648366a1f4 100644
--- a/dbms/src/Interpreters/CollectJoinOnKeysVisitor.cpp
+++ b/dbms/src/Interpreters/CollectJoinOnKeysVisitor.cpp
@@ -11,7 +11,6 @@ namespace ErrorCodes
 {
     extern const int INVALID_JOIN_ON_EXPRESSION;
     extern const int AMBIGUOUS_COLUMN_NAME;
-    extern const int NOT_IMPLEMENTED;
     extern const int LOGICAL_ERROR;
 }
 
diff --git a/dbms/src/Interpreters/Context.cpp b/dbms/src/Interpreters/Context.cpp
index 32185de0ee9..400ea0df202 100644
--- a/dbms/src/Interpreters/Context.cpp
+++ b/dbms/src/Interpreters/Context.cpp
@@ -78,25 +78,18 @@ namespace DB
 
 namespace ErrorCodes
 {
-    extern const int DATABASE_ACCESS_DENIED;
     extern const int UNKNOWN_DATABASE;
     extern const int UNKNOWN_TABLE;
     extern const int TABLE_ALREADY_EXISTS;
-    extern const int TABLE_WAS_NOT_DROPPED;
     extern const int DATABASE_ALREADY_EXISTS;
     extern const int THERE_IS_NO_SESSION;
     extern const int THERE_IS_NO_QUERY;
     extern const int NO_ELEMENTS_IN_CONFIG;
-    extern const int DDL_GUARD_IS_ACTIVE;
     extern const int TABLE_SIZE_EXCEEDS_MAX_DROP_SIZE_LIMIT;
-    extern const int PARTITION_SIZE_EXCEEDS_MAX_DROP_SIZE_LIMIT;
     extern const int SESSION_NOT_FOUND;
     extern const int SESSION_IS_LOCKED;
-    extern const int CANNOT_GET_CREATE_TABLE_QUERY;
     extern const int LOGICAL_ERROR;
-    extern const int SCALAR_ALREADY_EXISTS;
     extern const int UNKNOWN_SCALAR;
-    extern const int ACCESS_DENIED;
 }
 
 
diff --git a/dbms/src/Interpreters/DDLWorker.cpp b/dbms/src/Interpreters/DDLWorker.cpp
index d99781ab816..3431345bfae 100644
--- a/dbms/src/Interpreters/DDLWorker.cpp
+++ b/dbms/src/Interpreters/DDLWorker.cpp
@@ -47,15 +47,11 @@ namespace DB
 namespace ErrorCodes
 {
     extern const int LOGICAL_ERROR;
-    extern const int UNKNOWN_ELEMENT_IN_CONFIG;
-    extern const int INVALID_CONFIG_PARAMETER;
     extern const int UNKNOWN_FORMAT_VERSION;
-    extern const int INCONSISTENT_TABLE_ACCROSS_SHARDS;
     extern const int INCONSISTENT_CLUSTER_DEFINITION;
     extern const int TIMEOUT_EXCEEDED;
     extern const int UNKNOWN_TYPE_OF_QUERY;
     extern const int UNFINISHED;
-    extern const int UNKNOWN_STATUS_OF_DISTRIBUTED_DDL_TASK;
     extern const int QUERY_IS_PROHIBITED;
 }
 
diff --git a/dbms/src/Interpreters/ExpressionActions.cpp b/dbms/src/Interpreters/ExpressionActions.cpp
index df974cea586..9e2a825f430 100644
--- a/dbms/src/Interpreters/ExpressionActions.cpp
+++ b/dbms/src/Interpreters/ExpressionActions.cpp
@@ -29,7 +29,6 @@ namespace ErrorCodes
 {
     extern const int DUPLICATE_COLUMN;
     extern const int UNKNOWN_IDENTIFIER;
-    extern const int UNKNOWN_ACTION;
     extern const int NOT_FOUND_COLUMN_IN_BLOCK;
     extern const int TOO_MANY_TEMPORARY_COLUMNS;
     extern const int TOO_MANY_TEMPORARY_NON_CONST_COLUMNS;
diff --git a/dbms/src/Interpreters/InterpreterAlterQuery.cpp b/dbms/src/Interpreters/InterpreterAlterQuery.cpp
index c283d0c7efb..da0cfbf4d89 100644
--- a/dbms/src/Interpreters/InterpreterAlterQuery.cpp
+++ b/dbms/src/Interpreters/InterpreterAlterQuery.cpp
@@ -23,7 +23,6 @@ namespace DB
 namespace ErrorCodes
 {
     extern const int LOGICAL_ERROR;
-    extern const int ILLEGAL_COLUMN;
     extern const int SUPPORT_IS_DISABLED;
     extern const int INCORRECT_QUERY;
 }
diff --git a/dbms/src/Interpreters/InterpreterCreateQuery.cpp b/dbms/src/Interpreters/InterpreterCreateQuery.cpp
index 3d5014ac440..4f7f1f98fbd 100644
--- a/dbms/src/Interpreters/InterpreterCreateQuery.cpp
+++ b/dbms/src/Interpreters/InterpreterCreateQuery.cpp
@@ -59,13 +59,9 @@ namespace ErrorCodes
     extern const int TABLE_ALREADY_EXISTS;
     extern const int EMPTY_LIST_OF_COLUMNS_PASSED;
     extern const int INCORRECT_QUERY;
-    extern const int ENGINE_REQUIRED;
     extern const int UNKNOWN_DATABASE_ENGINE;
     extern const int DUPLICATE_COLUMN;
-    extern const int READONLY;
-    extern const int ILLEGAL_COLUMN;
     extern const int DATABASE_ALREADY_EXISTS;
-    extern const int QUERY_IS_PROHIBITED;
     extern const int THERE_IS_NO_DEFAULT_VALUE;
     extern const int BAD_DATABASE_FOR_TEMPORARY_TABLE;
     extern const int SUSPICIOUS_TYPE_FOR_LOW_CARDINALITY;
diff --git a/dbms/src/Interpreters/InterpreterCreateUserQuery.cpp b/dbms/src/Interpreters/InterpreterCreateUserQuery.cpp
index db7f34a2184..f15a319cb4a 100644
--- a/dbms/src/Interpreters/InterpreterCreateUserQuery.cpp
+++ b/dbms/src/Interpreters/InterpreterCreateUserQuery.cpp
@@ -13,7 +13,6 @@ namespace DB
 {
 namespace ErrorCodes
 {
-    extern const int SET_NON_GRANTED_ROLE;
 }
 
 
diff --git a/dbms/src/Interpreters/InterpreterDropQuery.cpp b/dbms/src/Interpreters/InterpreterDropQuery.cpp
index 4daa647fa9b..424eb80e646 100644
--- a/dbms/src/Interpreters/InterpreterDropQuery.cpp
+++ b/dbms/src/Interpreters/InterpreterDropQuery.cpp
@@ -18,14 +18,10 @@ namespace DB
 
 namespace ErrorCodes
 {
-    extern const int TABLE_WAS_NOT_DROPPED;
     extern const int DATABASE_NOT_EMPTY;
-    extern const int UNKNOWN_DATABASE;
-    extern const int READONLY;
     extern const int LOGICAL_ERROR;
     extern const int SYNTAX_ERROR;
     extern const int UNKNOWN_TABLE;
-    extern const int QUERY_IS_PROHIBITED;
     extern const int UNKNOWN_DICTIONARY;
 }
 
diff --git a/dbms/src/Interpreters/InterpreterFactory.cpp b/dbms/src/Interpreters/InterpreterFactory.cpp
index 0e241aab12d..b3b1fd498db 100644
--- a/dbms/src/Interpreters/InterpreterFactory.cpp
+++ b/dbms/src/Interpreters/InterpreterFactory.cpp
@@ -78,9 +78,7 @@ namespace DB
 {
 namespace ErrorCodes
 {
-    extern const int READONLY;
     extern const int UNKNOWN_TYPE_OF_QUERY;
-    extern const int QUERY_IS_PROHIBITED;
 }
 
 
diff --git a/dbms/src/Interpreters/InterpreterInsertQuery.cpp b/dbms/src/Interpreters/InterpreterInsertQuery.cpp
index e2fe6661974..bab361ab52d 100644
--- a/dbms/src/Interpreters/InterpreterInsertQuery.cpp
+++ b/dbms/src/Interpreters/InterpreterInsertQuery.cpp
@@ -29,7 +29,6 @@ namespace DB
 namespace ErrorCodes
 {
     extern const int NO_SUCH_COLUMN_IN_TABLE;
-    extern const int READONLY;
     extern const int ILLEGAL_COLUMN;
     extern const int DUPLICATE_COLUMN;
 }
diff --git a/dbms/src/Interpreters/InterpreterKillQueryQuery.cpp b/dbms/src/Interpreters/InterpreterKillQueryQuery.cpp
index 63fa814aadc..b7047b9d221 100644
--- a/dbms/src/Interpreters/InterpreterKillQueryQuery.cpp
+++ b/dbms/src/Interpreters/InterpreterKillQueryQuery.cpp
@@ -25,9 +25,7 @@ namespace DB
 
 namespace ErrorCodes
 {
-    extern const int READONLY;
     extern const int LOGICAL_ERROR;
-    extern const int CANNOT_KILL;
     extern const int ACCESS_DENIED;
 }
 
diff --git a/dbms/src/Interpreters/InterpreterOptimizeQuery.cpp b/dbms/src/Interpreters/InterpreterOptimizeQuery.cpp
index 74551329343..6048fa4388e 100644
--- a/dbms/src/Interpreters/InterpreterOptimizeQuery.cpp
+++ b/dbms/src/Interpreters/InterpreterOptimizeQuery.cpp
@@ -12,7 +12,6 @@ namespace DB
 
 namespace ErrorCodes
 {
-    extern const int BAD_ARGUMENTS;
 }
 
 
diff --git a/dbms/src/Interpreters/InterpreterSelectQuery.cpp b/dbms/src/Interpreters/InterpreterSelectQuery.cpp
index 63612075ff1..114ecf2b8b1 100644
--- a/dbms/src/Interpreters/InterpreterSelectQuery.cpp
+++ b/dbms/src/Interpreters/InterpreterSelectQuery.cpp
@@ -106,7 +106,6 @@ namespace DB
 namespace ErrorCodes
 {
     extern const int TOO_DEEP_SUBQUERIES;
-    extern const int THERE_IS_NO_COLUMN;
     extern const int SAMPLING_NOT_SUPPORTED;
     extern const int ILLEGAL_FINAL;
     extern const int ILLEGAL_PREWHERE;
@@ -114,7 +113,6 @@ namespace ErrorCodes
     extern const int LOGICAL_ERROR;
     extern const int NOT_IMPLEMENTED;
     extern const int PARAMETER_OUT_OF_BOUND;
-    extern const int ARGUMENT_OUT_OF_BOUND;
     extern const int INVALID_LIMIT_EXPRESSION;
     extern const int INVALID_WITH_FILL_EXPRESSION;
 }
diff --git a/dbms/src/Interpreters/InterpreterWatchQuery.cpp b/dbms/src/Interpreters/InterpreterWatchQuery.cpp
index 6a1fac7b97b..40606899c53 100644
--- a/dbms/src/Interpreters/InterpreterWatchQuery.cpp
+++ b/dbms/src/Interpreters/InterpreterWatchQuery.cpp
@@ -23,7 +23,6 @@ namespace DB
 
 namespace ErrorCodes
 {
-    extern const int UNKNOWN_STORAGE;
     extern const int UNKNOWN_TABLE;
     extern const int TOO_MANY_COLUMNS;
     extern const int SUPPORT_IS_DISABLED;
diff --git a/dbms/src/Interpreters/Join.cpp b/dbms/src/Interpreters/Join.cpp
index c53e61a565c..9a91239d4f3 100644
--- a/dbms/src/Interpreters/Join.cpp
+++ b/dbms/src/Interpreters/Join.cpp
@@ -33,7 +33,6 @@ namespace ErrorCodes
     extern const int LOGICAL_ERROR;
     extern const int SET_SIZE_LIMIT_EXCEEDED;
     extern const int TYPE_MISMATCH;
-    extern const int ILLEGAL_COLUMN;
 }
 
 
diff --git a/dbms/src/Interpreters/JoinToSubqueryTransformVisitor.cpp b/dbms/src/Interpreters/JoinToSubqueryTransformVisitor.cpp
index 60d8651f453..6d543643436 100644
--- a/dbms/src/Interpreters/JoinToSubqueryTransformVisitor.cpp
+++ b/dbms/src/Interpreters/JoinToSubqueryTransformVisitor.cpp
@@ -23,7 +23,6 @@ namespace DB
 namespace ErrorCodes
 {
     extern const int LOGICAL_ERROR;
-    extern const int TOO_DEEP_AST;
     extern const int AMBIGUOUS_COLUMN_NAME;
     extern const int NOT_IMPLEMENTED;
     extern const int UNKNOWN_IDENTIFIER;
diff --git a/dbms/src/Interpreters/MergeJoin.cpp b/dbms/src/Interpreters/MergeJoin.cpp
index 27b7d87b8ca..6e88ea4e159 100644
--- a/dbms/src/Interpreters/MergeJoin.cpp
+++ b/dbms/src/Interpreters/MergeJoin.cpp
@@ -20,7 +20,6 @@ namespace DB
 
 namespace ErrorCodes
 {
-    extern const int SET_SIZE_LIMIT_EXCEEDED;
     extern const int NOT_IMPLEMENTED;
     extern const int PARAMETER_OUT_OF_BOUND;
     extern const int NOT_ENOUGH_SPACE;
diff --git a/dbms/src/Interpreters/PredicateExpressionsOptimizer.cpp b/dbms/src/Interpreters/PredicateExpressionsOptimizer.cpp
index 9927091874c..950cc60433a 100644
--- a/dbms/src/Interpreters/PredicateExpressionsOptimizer.cpp
+++ b/dbms/src/Interpreters/PredicateExpressionsOptimizer.cpp
@@ -15,8 +15,6 @@ namespace DB
 
 namespace ErrorCodes
 {
-    extern const int LOGICAL_ERROR;
-    extern const int UNKNOWN_ELEMENT_IN_AST;
 }
 
 PredicateExpressionsOptimizer::PredicateExpressionsOptimizer(
diff --git a/dbms/src/Interpreters/ProcessList.cpp b/dbms/src/Interpreters/ProcessList.cpp
index 11675f32bd6..6b0c737421e 100644
--- a/dbms/src/Interpreters/ProcessList.cpp
+++ b/dbms/src/Interpreters/ProcessList.cpp
@@ -28,8 +28,6 @@ namespace ErrorCodes
     extern const int TOO_MANY_SIMULTANEOUS_QUERIES;
     extern const int QUERY_WITH_SAME_ID_IS_ALREADY_RUNNING;
     extern const int LOGICAL_ERROR;
-    extern const int TOO_MANY_ROWS;
-    extern const int TOO_MANY_BYTES;
 }
 
 
diff --git a/dbms/src/Interpreters/RequiredSourceColumnsVisitor.h b/dbms/src/Interpreters/RequiredSourceColumnsVisitor.h
index b42a95f29ee..1f6ff482e3a 100644
--- a/dbms/src/Interpreters/RequiredSourceColumnsVisitor.h
+++ b/dbms/src/Interpreters/RequiredSourceColumnsVisitor.h
@@ -8,7 +8,6 @@ namespace DB
 
 namespace ErrorCodes
 {
-    extern const int NUMBER_OF_ARGUMENTS_DOESNT_MATCH;
 }
 
 class ASTIdentifier;
diff --git a/dbms/src/Interpreters/SyntaxAnalyzer.cpp b/dbms/src/Interpreters/SyntaxAnalyzer.cpp
index a8f7d1e2ecc..90736835b0e 100644
--- a/dbms/src/Interpreters/SyntaxAnalyzer.cpp
+++ b/dbms/src/Interpreters/SyntaxAnalyzer.cpp
@@ -48,7 +48,6 @@ namespace DB
 namespace ErrorCodes
 {
     extern const int EMPTY_NESTED_TABLE;
-    extern const int LOGICAL_ERROR;
     extern const int INVALID_JOIN_ON_EXPRESSION;
     extern const int EMPTY_LIST_OF_COLUMNS_QUERIED;
     extern const int NOT_IMPLEMENTED;
diff --git a/dbms/src/Interpreters/TablesStatus.h b/dbms/src/Interpreters/TablesStatus.h
index d083e67a0bf..c9e16e9615b 100644
--- a/dbms/src/Interpreters/TablesStatus.h
+++ b/dbms/src/Interpreters/TablesStatus.h
@@ -11,8 +11,6 @@ namespace DB
 
 namespace ErrorCodes
 {
-    extern const int LOGICAL_ERROR;
-    extern const int TOO_LARGE_ARRAY_SIZE;
 }
 
 class ReadBuffer;
diff --git a/dbms/src/Interpreters/TranslateQualifiedNamesVisitor.cpp b/dbms/src/Interpreters/TranslateQualifiedNamesVisitor.cpp
index 699b431a22d..04f59b81f0f 100644
--- a/dbms/src/Interpreters/TranslateQualifiedNamesVisitor.cpp
+++ b/dbms/src/Interpreters/TranslateQualifiedNamesVisitor.cpp
@@ -25,7 +25,6 @@ namespace DB
 namespace ErrorCodes
 {
     extern const int UNKNOWN_IDENTIFIER;
-    extern const int UNKNOWN_ELEMENT_IN_AST;
     extern const int LOGICAL_ERROR;
 }
 
diff --git a/dbms/src/Interpreters/evaluateConstantExpression.cpp b/dbms/src/Interpreters/evaluateConstantExpression.cpp
index 23cdcbd9fd5..37e990fd5fc 100644
--- a/dbms/src/Interpreters/evaluateConstantExpression.cpp
+++ b/dbms/src/Interpreters/evaluateConstantExpression.cpp
@@ -26,7 +26,6 @@ namespace ErrorCodes
 {
     extern const int LOGICAL_ERROR;
     extern const int BAD_ARGUMENTS;
-    extern const int UNKNOWN_DATABASE;
 }
 
 
diff --git a/dbms/src/Interpreters/executeQuery.cpp b/dbms/src/Interpreters/executeQuery.cpp
index ac67ded4b45..7f9d872b023 100644
--- a/dbms/src/Interpreters/executeQuery.cpp
+++ b/dbms/src/Interpreters/executeQuery.cpp
@@ -51,8 +51,6 @@ namespace DB
 
 namespace ErrorCodes
 {
-    extern const int LOGICAL_ERROR;
-    extern const int QUERY_IS_TOO_LARGE;
     extern const int INTO_OUTFILE_NOT_ALLOWED;
     extern const int QUERY_WAS_CANCELLED;
 }
diff --git a/dbms/src/Parsers/ASTColumnsMatcher.h b/dbms/src/Parsers/ASTColumnsMatcher.h
index e5ec9a2873d..91c8ed68edc 100644
--- a/dbms/src/Parsers/ASTColumnsMatcher.h
+++ b/dbms/src/Parsers/ASTColumnsMatcher.h
@@ -16,7 +16,6 @@ class WriteBuffer;
 
 namespace ErrorCodes
 {
-    extern const int CANNOT_COMPILE_REGEXP;
 }
 
 struct AsteriskSemantic;
diff --git a/dbms/src/Parsers/ASTSystemQuery.cpp b/dbms/src/Parsers/ASTSystemQuery.cpp
index 41969f3fc63..deaed070484 100644
--- a/dbms/src/Parsers/ASTSystemQuery.cpp
+++ b/dbms/src/Parsers/ASTSystemQuery.cpp
@@ -10,7 +10,6 @@ namespace DB
 namespace ErrorCodes
 {
     extern const int BAD_TYPE_OF_FIELD;
-    extern const int NOT_IMPLEMENTED;
 }
 
 
diff --git a/dbms/src/Parsers/IParserBase.cpp b/dbms/src/Parsers/IParserBase.cpp
index e4caffa992e..0aade8e36ac 100644
--- a/dbms/src/Parsers/IParserBase.cpp
+++ b/dbms/src/Parsers/IParserBase.cpp
@@ -6,7 +6,6 @@ namespace DB
 
 namespace ErrorCodes
 {
-    extern const int LOGICAL_ERROR;
 }
 
 
diff --git a/dbms/src/Parsers/ParserCreateRowPolicyQuery.cpp b/dbms/src/Parsers/ParserCreateRowPolicyQuery.cpp
index d035bffbed3..00dd1df1d7a 100644
--- a/dbms/src/Parsers/ParserCreateRowPolicyQuery.cpp
+++ b/dbms/src/Parsers/ParserCreateRowPolicyQuery.cpp
@@ -13,7 +13,6 @@ namespace DB
 {
 namespace ErrorCodes
 {
-    extern const int SYNTAX_ERROR;
 }
 
 
diff --git a/dbms/src/Parsers/ParserCreateUserQuery.cpp b/dbms/src/Parsers/ParserCreateUserQuery.cpp
index bf3515489f6..96231f62980 100644
--- a/dbms/src/Parsers/ParserCreateUserQuery.cpp
+++ b/dbms/src/Parsers/ParserCreateUserQuery.cpp
@@ -15,7 +15,6 @@ namespace DB
 {
 namespace ErrorCodes
 {
-    extern const int SYNTAX_ERROR;
 }
 
 
diff --git a/dbms/src/Parsers/ParserDropQuery.cpp b/dbms/src/Parsers/ParserDropQuery.cpp
index c66d36c0f20..c82b4d4997c 100644
--- a/dbms/src/Parsers/ParserDropQuery.cpp
+++ b/dbms/src/Parsers/ParserDropQuery.cpp
@@ -10,8 +10,6 @@ namespace DB
 
 namespace ErrorCodes
 {
-    extern const int SYNTAX_ERROR;
-    extern const int LOGICAL_ERROR;
 }
 
 bool ParserDropQuery::parseImpl(Pos & pos, ASTPtr & node, Expected & expected)
diff --git a/dbms/src/Parsers/ParserSelectQuery.cpp b/dbms/src/Parsers/ParserSelectQuery.cpp
index cc74fbc5f8b..927ac45001e 100644
--- a/dbms/src/Parsers/ParserSelectQuery.cpp
+++ b/dbms/src/Parsers/ParserSelectQuery.cpp
@@ -15,7 +15,6 @@ namespace DB
 
 namespace ErrorCodes
 {
-    extern const int SYNTAX_ERROR;
     extern const int TOP_AND_LIMIT_TOGETHER;
     extern const int WITH_TIES_WITHOUT_ORDER_BY;
     extern const int LIMIT_BY_WITH_TIES_IS_NOT_SUPPORTED;
diff --git a/dbms/src/Parsers/ParserSystemQuery.cpp b/dbms/src/Parsers/ParserSystemQuery.cpp
index 0c93faa86a0..720ca666023 100644
--- a/dbms/src/Parsers/ParserSystemQuery.cpp
+++ b/dbms/src/Parsers/ParserSystemQuery.cpp
@@ -8,7 +8,6 @@
 
 namespace ErrorCodes
 {
-    extern const int NOT_IMPLEMENTED;
 }
 
 
diff --git a/dbms/src/Processors/Formats/IRowInputFormat.cpp b/dbms/src/Processors/Formats/IRowInputFormat.cpp
index 66e53378071..d911dfba339 100644
--- a/dbms/src/Processors/Formats/IRowInputFormat.cpp
+++ b/dbms/src/Processors/Formats/IRowInputFormat.cpp
@@ -17,7 +17,6 @@ namespace ErrorCodes
     extern const int CANNOT_PARSE_UUID;
     extern const int TOO_LARGE_STRING_SIZE;
     extern const int INCORRECT_NUMBER_OF_COLUMNS;
-    extern const int TIMEOUT_EXCEEDED;
 }
 
 
diff --git a/dbms/src/Processors/Formats/Impl/ArrowColumnToCHColumn.cpp b/dbms/src/Processors/Formats/Impl/ArrowColumnToCHColumn.cpp
index 0615dd2a5d1..0fa1de9da65 100644
--- a/dbms/src/Processors/Formats/Impl/ArrowColumnToCHColumn.cpp
+++ b/dbms/src/Processors/Formats/Impl/ArrowColumnToCHColumn.cpp
@@ -23,8 +23,6 @@ namespace DB
         extern const int UNKNOWN_TYPE;
         extern const int VALUE_IS_OUT_OF_RANGE_OF_DATA_TYPE;
         extern const int CANNOT_READ_ALL_DATA;
-        extern const int EMPTY_DATA_PASSED;
-        extern const int SIZES_OF_COLUMNS_DOESNT_MATCH;
         extern const int CANNOT_CONVERT_TYPE;
         extern const int CANNOT_INSERT_NULL_IN_ORDINARY_COLUMN;
         extern const int THERE_IS_NO_COLUMN;
diff --git a/dbms/src/Processors/Formats/Impl/AvroRowOutputFormat.cpp b/dbms/src/Processors/Formats/Impl/AvroRowOutputFormat.cpp
index 26b427dfa31..8f72d46efe6 100644
--- a/dbms/src/Processors/Formats/Impl/AvroRowOutputFormat.cpp
+++ b/dbms/src/Processors/Formats/Impl/AvroRowOutputFormat.cpp
@@ -45,12 +45,7 @@ namespace DB
 {
 namespace ErrorCodes
 {
-    extern const int BAD_TYPE_OF_FIELD;
     extern const int BAD_ARGUMENTS;
-    extern const int THERE_IS_NO_COLUMN;
-    extern const int LOGICAL_ERROR;
-    extern const int INCORRECT_DATA;
-    extern const int CANNOT_READ_ALL_DATA;
 }
 
 class OutputStreamWriteBufferAdapter : public avro::OutputStream
diff --git a/dbms/src/Processors/Formats/Impl/CSVRowInputFormat.cpp b/dbms/src/Processors/Formats/Impl/CSVRowInputFormat.cpp
index e5920f33dc6..0971d3adc18 100644
--- a/dbms/src/Processors/Formats/Impl/CSVRowInputFormat.cpp
+++ b/dbms/src/Processors/Formats/Impl/CSVRowInputFormat.cpp
@@ -14,7 +14,6 @@ namespace DB
 namespace ErrorCodes
 {
     extern const int INCORRECT_DATA;
-    extern const int LOGICAL_ERROR;
 }
 
 
diff --git a/dbms/src/Processors/Formats/Impl/CapnProtoRowInputFormat.cpp b/dbms/src/Processors/Formats/Impl/CapnProtoRowInputFormat.cpp
index afa9f4d4fa0..bc00fec7611 100644
--- a/dbms/src/Processors/Formats/Impl/CapnProtoRowInputFormat.cpp
+++ b/dbms/src/Processors/Formats/Impl/CapnProtoRowInputFormat.cpp
@@ -20,7 +20,6 @@ namespace DB
 namespace ErrorCodes
 {
     extern const int BAD_TYPE_OF_FIELD;
-    extern const int BAD_ARGUMENTS;
     extern const int THERE_IS_NO_COLUMN;
     extern const int LOGICAL_ERROR;
 }
diff --git a/dbms/src/Processors/Formats/Impl/JSONCompactEachRowRowInputFormat.cpp b/dbms/src/Processors/Formats/Impl/JSONCompactEachRowRowInputFormat.cpp
index 61a5f649ed1..26c86812967 100644
--- a/dbms/src/Processors/Formats/Impl/JSONCompactEachRowRowInputFormat.cpp
+++ b/dbms/src/Processors/Formats/Impl/JSONCompactEachRowRowInputFormat.cpp
@@ -12,7 +12,6 @@ namespace ErrorCodes
 {
     extern const int INCORRECT_DATA;
     extern const int CANNOT_READ_ALL_DATA;
-    extern const int LOGICAL_ERROR;
 }
 
 
diff --git a/dbms/src/Processors/Formats/Impl/PrettyBlockOutputFormat.cpp b/dbms/src/Processors/Formats/Impl/PrettyBlockOutputFormat.cpp
index 6a3a34278fe..048e9f23e4e 100644
--- a/dbms/src/Processors/Formats/Impl/PrettyBlockOutputFormat.cpp
+++ b/dbms/src/Processors/Formats/Impl/PrettyBlockOutputFormat.cpp
@@ -13,7 +13,6 @@ namespace DB
 
 namespace ErrorCodes
 {
-    extern const int ILLEGAL_COLUMN;
 }
 
 
diff --git a/dbms/src/Processors/Formats/Impl/PrettyCompactBlockOutputFormat.cpp b/dbms/src/Processors/Formats/Impl/PrettyCompactBlockOutputFormat.cpp
index 84e222d073c..554f0f00e39 100644
--- a/dbms/src/Processors/Formats/Impl/PrettyCompactBlockOutputFormat.cpp
+++ b/dbms/src/Processors/Formats/Impl/PrettyCompactBlockOutputFormat.cpp
@@ -12,7 +12,6 @@ namespace DB
 namespace ErrorCodes
 {
 
-extern const int ILLEGAL_COLUMN;
 
 }
 
diff --git a/dbms/src/Processors/Formats/Impl/ProtobufRowOutputFormat.cpp b/dbms/src/Processors/Formats/Impl/ProtobufRowOutputFormat.cpp
index da567e60475..ea7a63d588f 100644
--- a/dbms/src/Processors/Formats/Impl/ProtobufRowOutputFormat.cpp
+++ b/dbms/src/Processors/Formats/Impl/ProtobufRowOutputFormat.cpp
@@ -15,8 +15,6 @@ namespace DB
 {
 namespace ErrorCodes
 {
-    extern const int NOT_IMPLEMENTED;
-    extern const int NO_DATA_FOR_REQUIRED_PROTOBUF_FIELD;
 }
 
 
diff --git a/dbms/src/Processors/Formats/Impl/TabSeparatedRowInputFormat.cpp b/dbms/src/Processors/Formats/Impl/TabSeparatedRowInputFormat.cpp
index d20d7802d5c..706941a3dc6 100644
--- a/dbms/src/Processors/Formats/Impl/TabSeparatedRowInputFormat.cpp
+++ b/dbms/src/Processors/Formats/Impl/TabSeparatedRowInputFormat.cpp
@@ -14,7 +14,6 @@ namespace DB
 namespace ErrorCodes
 {
     extern const int INCORRECT_DATA;
-    extern const int LOGICAL_ERROR;
 }
 
 
diff --git a/dbms/src/Processors/Formats/Impl/ValuesBlockInputFormat.cpp b/dbms/src/Processors/Formats/Impl/ValuesBlockInputFormat.cpp
index 9ce3d62a244..d656598e45d 100644
--- a/dbms/src/Processors/Formats/Impl/ValuesBlockInputFormat.cpp
+++ b/dbms/src/Processors/Formats/Impl/ValuesBlockInputFormat.cpp
@@ -20,12 +20,6 @@ namespace DB
 namespace ErrorCodes
 {
     extern const int CANNOT_PARSE_INPUT_ASSERTION_FAILED;
-    extern const int CANNOT_PARSE_QUOTED_STRING;
-    extern const int CANNOT_PARSE_NUMBER;
-    extern const int CANNOT_PARSE_DATE;
-    extern const int CANNOT_PARSE_DATETIME;
-    extern const int CANNOT_READ_ARRAY_FROM_TEXT;
-    extern const int CANNOT_PARSE_DATE;
     extern const int SYNTAX_ERROR;
     extern const int TYPE_MISMATCH;
     extern const int SUPPORT_IS_DISABLED;
diff --git a/dbms/src/Processors/Sources/SourceWithProgress.cpp b/dbms/src/Processors/Sources/SourceWithProgress.cpp
index 6b62123933c..0cac415aedb 100644
--- a/dbms/src/Processors/Sources/SourceWithProgress.cpp
+++ b/dbms/src/Processors/Sources/SourceWithProgress.cpp
@@ -10,7 +10,6 @@ namespace ErrorCodes
 {
     extern const int TOO_MANY_ROWS;
     extern const int TOO_MANY_BYTES;
-    extern const int TIMEOUT_EXCEEDED;
 }
 
 void SourceWithProgress::work()
diff --git a/dbms/src/Processors/Transforms/LimitsCheckingTransform.cpp b/dbms/src/Processors/Transforms/LimitsCheckingTransform.cpp
index 57641a54b70..3ead146abc1 100644
--- a/dbms/src/Processors/Transforms/LimitsCheckingTransform.cpp
+++ b/dbms/src/Processors/Transforms/LimitsCheckingTransform.cpp
@@ -7,13 +7,7 @@ namespace DB
 namespace ErrorCodes
 {
     extern const int TOO_MANY_ROWS;
-    extern const int TOO_MANY_BYTES;
     extern const int TOO_MANY_ROWS_OR_BYTES;
-    extern const int TIMEOUT_EXCEEDED;
-    extern const int TOO_SLOW;
-    extern const int LOGICAL_ERROR;
-    extern const int BLOCKS_HAVE_DIFFERENT_STRUCTURE;
-    extern const int TOO_DEEP_PIPELINE;
 }
 
 
diff --git a/dbms/src/Storages/AlterCommands.cpp b/dbms/src/Storages/AlterCommands.cpp
index 49286108e64..c756d7d79e2 100644
--- a/dbms/src/Storages/AlterCommands.cpp
+++ b/dbms/src/Storages/AlterCommands.cpp
@@ -32,7 +32,6 @@ namespace ErrorCodes
     extern const int BAD_ARGUMENTS;
     extern const int NOT_FOUND_COLUMN_IN_BLOCK;
     extern const int LOGICAL_ERROR;
-    extern const int UNKNOWN_SETTING;
     extern const int DUPLICATE_COLUMN;
 }
 
diff --git a/dbms/src/Storages/CompressionCodecSelector.h b/dbms/src/Storages/CompressionCodecSelector.h
index 4c7ad8ba973..d194adc9317 100644
--- a/dbms/src/Storages/CompressionCodecSelector.h
+++ b/dbms/src/Storages/CompressionCodecSelector.h
@@ -11,7 +11,6 @@ namespace DB
 
 namespace ErrorCodes
 {
-    extern const int UNKNOWN_COMPRESSION_METHOD;
     extern const int UNKNOWN_ELEMENT_IN_CONFIG;
 }
 
diff --git a/dbms/src/Storages/Distributed/DirectoryMonitor.cpp b/dbms/src/Storages/Distributed/DirectoryMonitor.cpp
index 77467da511e..483384fe719 100644
--- a/dbms/src/Storages/Distributed/DirectoryMonitor.cpp
+++ b/dbms/src/Storages/Distributed/DirectoryMonitor.cpp
@@ -35,14 +35,11 @@ namespace DB
 
 namespace ErrorCodes
 {
-    extern const int ABORTED;
     extern const int UNKNOWN_CODEC;
     extern const int CANNOT_DECOMPRESS;
-    extern const int INCORRECT_FILE_NAME;
     extern const int CHECKSUM_DOESNT_MATCH;
     extern const int TOO_LARGE_SIZE_COMPRESSED;
     extern const int ATTEMPT_TO_READ_AFTER_EOF;
-    extern const int CORRUPTED_DATA;
 }
 
 
diff --git a/dbms/src/Storages/IStorage.cpp b/dbms/src/Storages/IStorage.cpp
index 36b7376de18..dd7722ce7b9 100644
--- a/dbms/src/Storages/IStorage.cpp
+++ b/dbms/src/Storages/IStorage.cpp
@@ -25,8 +25,6 @@ namespace ErrorCodes
     extern const int NO_SUCH_COLUMN_IN_TABLE;
     extern const int NOT_FOUND_COLUMN_IN_BLOCK;
     extern const int TYPE_MISMATCH;
-    extern const int SETTINGS_ARE_NOT_SUPPORTED;
-    extern const int UNKNOWN_SETTING;
     extern const int TABLE_IS_DROPPED;
     extern const int NOT_IMPLEMENTED;
 }
diff --git a/dbms/src/Storages/Kafka/StorageKafka.cpp b/dbms/src/Storages/Kafka/StorageKafka.cpp
index 16aee94a00a..82c1f2a3ea6 100644
--- a/dbms/src/Storages/Kafka/StorageKafka.cpp
+++ b/dbms/src/Storages/Kafka/StorageKafka.cpp
@@ -39,16 +39,9 @@ namespace DB
 
 namespace ErrorCodes
 {
-    extern const int INCORRECT_DATA;
-    extern const int UNKNOWN_EXCEPTION;
-    extern const int CANNOT_READ_FROM_ISTREAM;
-    extern const int INVALID_CONFIG_PARAMETER;
     extern const int LOGICAL_ERROR;
     extern const int BAD_ARGUMENTS;
     extern const int NUMBER_OF_ARGUMENTS_DOESNT_MATCH;
-    extern const int UNSUPPORTED_METHOD;
-    extern const int UNKNOWN_SETTING;
-    extern const int READONLY_SETTING;
 }
 
 namespace
diff --git a/dbms/src/Storages/MergeTree/DataPartsExchange.cpp b/dbms/src/Storages/MergeTree/DataPartsExchange.cpp
index f34db71b633..79cb1345412 100644
--- a/dbms/src/Storages/MergeTree/DataPartsExchange.cpp
+++ b/dbms/src/Storages/MergeTree/DataPartsExchange.cpp
@@ -23,7 +23,6 @@ namespace ErrorCodes
     extern const int BAD_SIZE_OF_FILE_IN_DATA_PART;
     extern const int CANNOT_WRITE_TO_OSTREAM;
     extern const int CHECKSUM_DOESNT_MATCH;
-    extern const int UNKNOWN_TABLE;
     extern const int UNKNOWN_PROTOCOL;
     extern const int INSECURE_PATH;
 }
diff --git a/dbms/src/Storages/MergeTree/IMergeTreeDataPart.h b/dbms/src/Storages/MergeTree/IMergeTreeDataPart.h
index 6b040fdc0a3..61b5ba43165 100644
--- a/dbms/src/Storages/MergeTree/IMergeTreeDataPart.h
+++ b/dbms/src/Storages/MergeTree/IMergeTreeDataPart.h
@@ -37,7 +37,6 @@ class IMergeTreeDataPartWriter;
 
 namespace ErrorCodes
 {
-    extern const int NOT_IMPLEMETED;
 }
 
 /// Description of the data part.
diff --git a/dbms/src/Storages/MergeTree/IMergeTreeReader.cpp b/dbms/src/Storages/MergeTree/IMergeTreeReader.cpp
index d1a366ee809..161b468913f 100644
--- a/dbms/src/Storages/MergeTree/IMergeTreeReader.cpp
+++ b/dbms/src/Storages/MergeTree/IMergeTreeReader.cpp
@@ -19,9 +19,6 @@ namespace
 namespace ErrorCodes
 {
     extern const int LOGICAL_ERROR;
-    extern const int NOT_FOUND_EXPECTED_DATA_PART;
-    extern const int MEMORY_LIMIT_EXCEEDED;
-    extern const int ARGUMENT_OUT_OF_BOUND;
 }
 
 
diff --git a/dbms/src/Storages/MergeTree/KeyCondition.cpp b/dbms/src/Storages/MergeTree/KeyCondition.cpp
index f8c7db4a423..b714734d6f3 100644
--- a/dbms/src/Storages/MergeTree/KeyCondition.cpp
+++ b/dbms/src/Storages/MergeTree/KeyCondition.cpp
@@ -26,7 +26,6 @@ namespace ErrorCodes
 {
     extern const int LOGICAL_ERROR;
     extern const int BAD_TYPE_OF_FIELD;
-    extern const int NUMBER_OF_COLUMNS_DOESNT_MATCH;
 }
 
 
diff --git a/dbms/src/Storages/MergeTree/MergeTreeBaseSelectProcessor.cpp b/dbms/src/Storages/MergeTree/MergeTreeBaseSelectProcessor.cpp
index 5539bbd57a1..f1d4f916473 100644
--- a/dbms/src/Storages/MergeTree/MergeTreeBaseSelectProcessor.cpp
+++ b/dbms/src/Storages/MergeTree/MergeTreeBaseSelectProcessor.cpp
@@ -13,7 +13,6 @@ namespace DB
 
 namespace ErrorCodes
 {
-    extern const int ILLEGAL_TYPE_OF_COLUMN_FOR_FILTER;
     extern const int LOGICAL_ERROR;
 }
 
diff --git a/dbms/src/Storages/MergeTree/MergeTreeData.cpp b/dbms/src/Storages/MergeTree/MergeTreeData.cpp
index 1c94db88c2a..04387b64372 100644
--- a/dbms/src/Storages/MergeTree/MergeTreeData.cpp
+++ b/dbms/src/Storages/MergeTree/MergeTreeData.cpp
@@ -86,13 +86,11 @@ namespace ErrorCodes
 {
     extern const int BAD_ARGUMENTS;
     extern const int MEMORY_LIMIT_EXCEEDED;
-    extern const int SYNTAX_ERROR;
     extern const int INVALID_PARTITION_VALUE;
     extern const int METADATA_MISMATCH;
     extern const int PART_IS_TEMPORARILY_LOCKED;
     extern const int TOO_MANY_PARTS;
     extern const int INCOMPATIBLE_COLUMNS;
-    extern const int CANNOT_UPDATE_COLUMN;
     extern const int CANNOT_ALLOCATE_MEMORY;
     extern const int CANNOT_MUNMAP;
     extern const int CANNOT_MREMAP;
diff --git a/dbms/src/Storages/MergeTree/MergeTreeData.h b/dbms/src/Storages/MergeTree/MergeTreeData.h
index fee083b1039..aad681aae48 100644
--- a/dbms/src/Storages/MergeTree/MergeTreeData.h
+++ b/dbms/src/Storages/MergeTree/MergeTreeData.h
@@ -41,13 +41,6 @@ using ExpressionActionsPtr = std::shared_ptr<ExpressionActions>;
 namespace ErrorCodes
 {
     extern const int LOGICAL_ERROR;
-    extern const int INVALID_PARTITION_NAME;
-    extern const int NO_SUCH_DATA_PART;
-    extern const int DUPLICATE_DATA_PART;
-    extern const int DIRECTORY_ALREADY_EXISTS;
-    extern const int TOO_MANY_UNEXPECTED_DATA_PARTS;
-    extern const int NO_SUCH_COLUMN_IN_TABLE;
-    extern const int TABLE_DIFFERS_TOO_MUCH;
 }
 
 
diff --git a/dbms/src/Storages/MergeTree/MergeTreeDataSelectExecutor.cpp b/dbms/src/Storages/MergeTree/MergeTreeDataSelectExecutor.cpp
index df686842d11..5a420712bec 100644
--- a/dbms/src/Storages/MergeTree/MergeTreeDataSelectExecutor.cpp
+++ b/dbms/src/Storages/MergeTree/MergeTreeDataSelectExecutor.cpp
@@ -76,7 +76,6 @@ namespace DB
 namespace ErrorCodes
 {
     extern const int INDEX_NOT_USED;
-    extern const int SAMPLING_NOT_SUPPORTED;
     extern const int ILLEGAL_TYPE_OF_COLUMN_FOR_FILTER;
     extern const int ILLEGAL_COLUMN;
     extern const int ARGUMENT_OUT_OF_BOUND;
diff --git a/dbms/src/Storages/MergeTree/MergeTreeIndexAggregatorBloomFilter.cpp b/dbms/src/Storages/MergeTree/MergeTreeIndexAggregatorBloomFilter.cpp
index f5cd9449c0e..ce49e1ff858 100644
--- a/dbms/src/Storages/MergeTree/MergeTreeIndexAggregatorBloomFilter.cpp
+++ b/dbms/src/Storages/MergeTree/MergeTreeIndexAggregatorBloomFilter.cpp
@@ -16,7 +16,6 @@ namespace DB
 namespace ErrorCodes
 {
     extern const int LOGICAL_ERROR;
-    extern const int ILLEGAL_COLUMN;
 }
 
 MergeTreeIndexAggregatorBloomFilter::MergeTreeIndexAggregatorBloomFilter(
diff --git a/dbms/src/Storages/MergeTree/MergeTreeIndexBloomFilter.cpp b/dbms/src/Storages/MergeTree/MergeTreeIndexBloomFilter.cpp
index 24af19b20cf..1cb37c6ec95 100644
--- a/dbms/src/Storages/MergeTree/MergeTreeIndexBloomFilter.cpp
+++ b/dbms/src/Storages/MergeTree/MergeTreeIndexBloomFilter.cpp
@@ -21,7 +21,6 @@ namespace DB
 
 namespace ErrorCodes
 {
-    extern const int LOGICAL_ERROR;
     extern const int INCORRECT_QUERY;
 }
 
diff --git a/dbms/src/Storages/MergeTree/MergeTreeIndexGranularity.cpp b/dbms/src/Storages/MergeTree/MergeTreeIndexGranularity.cpp
index 4901900b6ba..bca0d0cb883 100644
--- a/dbms/src/Storages/MergeTree/MergeTreeIndexGranularity.cpp
+++ b/dbms/src/Storages/MergeTree/MergeTreeIndexGranularity.cpp
@@ -7,7 +7,6 @@ namespace DB
 {
 namespace ErrorCodes
 {
-    extern const int LOGICAL_ERROR;
 }
 
 MergeTreeIndexGranularity::MergeTreeIndexGranularity(const std::vector<size_t> & marks_rows_partial_sums_)
diff --git a/dbms/src/Storages/MergeTree/MergeTreeIndices.cpp b/dbms/src/Storages/MergeTree/MergeTreeIndices.cpp
index 4e5a7c0c243..9fe475a00c7 100644
--- a/dbms/src/Storages/MergeTree/MergeTreeIndices.cpp
+++ b/dbms/src/Storages/MergeTree/MergeTreeIndices.cpp
@@ -16,7 +16,6 @@ namespace ErrorCodes
 {
     extern const int LOGICAL_ERROR;
     extern const int INCORRECT_QUERY;
-    extern const int UNKNOWN_EXCEPTION;
 }
 
 void MergeTreeIndexFactory::registerIndex(const std::string & name, Creator creator)
diff --git a/dbms/src/Storages/MergeTree/MergeTreePartsMover.cpp b/dbms/src/Storages/MergeTree/MergeTreePartsMover.cpp
index 66c72f8d1a6..ef19a24686e 100644
--- a/dbms/src/Storages/MergeTree/MergeTreePartsMover.cpp
+++ b/dbms/src/Storages/MergeTree/MergeTreePartsMover.cpp
@@ -10,8 +10,6 @@ namespace DB
 namespace ErrorCodes
 {
     extern const int ABORTED;
-    extern const int NO_SUCH_DATA_PART;
-    extern const int LOGICAL_ERROR;
 }
 
 namespace
diff --git a/dbms/src/Storages/MergeTree/MergeTreeReaderCompact.cpp b/dbms/src/Storages/MergeTree/MergeTreeReaderCompact.cpp
index 533a66c0beb..936644cd9e3 100644
--- a/dbms/src/Storages/MergeTree/MergeTreeReaderCompact.cpp
+++ b/dbms/src/Storages/MergeTree/MergeTreeReaderCompact.cpp
@@ -9,9 +9,6 @@ namespace DB
 
 namespace ErrorCodes
 {
-    extern const int LOGICAL_ERROR;
-    extern const int NOT_FOUND_EXPECTED_DATA_PART;
-    extern const int MEMORY_LIMIT_EXCEEDED;
     extern const int ARGUMENT_OUT_OF_BOUND;
 }
 
diff --git a/dbms/src/Storages/MergeTree/MergeTreeReaderStream.cpp b/dbms/src/Storages/MergeTree/MergeTreeReaderStream.cpp
index b132bda0f9e..140971fb6d4 100644
--- a/dbms/src/Storages/MergeTree/MergeTreeReaderStream.cpp
+++ b/dbms/src/Storages/MergeTree/MergeTreeReaderStream.cpp
@@ -8,9 +8,6 @@ namespace DB
 
 namespace ErrorCodes
 {
-    extern const int LOGICAL_ERROR;
-    extern const int CORRUPTED_DATA;
-    extern const int CANNOT_READ_ALL_DATA;
     extern const int ARGUMENT_OUT_OF_BOUND;
 }
 
diff --git a/dbms/src/Storages/MergeTree/MergeTreeReaderWide.cpp b/dbms/src/Storages/MergeTree/MergeTreeReaderWide.cpp
index da3be711f22..21f8b31aaea 100644
--- a/dbms/src/Storages/MergeTree/MergeTreeReaderWide.cpp
+++ b/dbms/src/Storages/MergeTree/MergeTreeReaderWide.cpp
@@ -20,9 +20,7 @@ namespace
 namespace ErrorCodes
 {
     extern const int LOGICAL_ERROR;
-    extern const int NOT_FOUND_EXPECTED_DATA_PART;
     extern const int MEMORY_LIMIT_EXCEEDED;
-    extern const int ARGUMENT_OUT_OF_BOUND;
 }
 
 MergeTreeReaderWide::MergeTreeReaderWide(
diff --git a/dbms/src/Storages/MergeTree/MergeTreeWhereOptimizer.cpp b/dbms/src/Storages/MergeTree/MergeTreeWhereOptimizer.cpp
index 699f2d0207f..311a09f3461 100644
--- a/dbms/src/Storages/MergeTree/MergeTreeWhereOptimizer.cpp
+++ b/dbms/src/Storages/MergeTree/MergeTreeWhereOptimizer.cpp
@@ -20,7 +20,6 @@ namespace DB
 
 namespace ErrorCodes
 {
-    extern const int LOGICAL_ERROR;
 }
 
 /// Conditions like "x = N" are considered good if abs(N) > threshold.
diff --git a/dbms/src/Storages/MergeTree/MergedBlockOutputStream.cpp b/dbms/src/Storages/MergeTree/MergedBlockOutputStream.cpp
index 59fe231ee80..b60f5fe104e 100644
--- a/dbms/src/Storages/MergeTree/MergedBlockOutputStream.cpp
+++ b/dbms/src/Storages/MergeTree/MergedBlockOutputStream.cpp
@@ -7,7 +7,6 @@ namespace DB
 
 namespace ErrorCodes
 {
-    extern const int BAD_ARGUMENTS;
 }
 
 
diff --git a/dbms/src/Storages/MergeTree/ReplicatedMergeTreeBlockOutputStream.cpp b/dbms/src/Storages/MergeTree/ReplicatedMergeTreeBlockOutputStream.cpp
index b25b4d3d804..fda0a8eb5a8 100644
--- a/dbms/src/Storages/MergeTree/ReplicatedMergeTreeBlockOutputStream.cpp
+++ b/dbms/src/Storages/MergeTree/ReplicatedMergeTreeBlockOutputStream.cpp
@@ -20,13 +20,11 @@ namespace ErrorCodes
 {
     extern const int TOO_FEW_LIVE_REPLICAS;
     extern const int UNSATISFIED_QUORUM_FOR_PREVIOUS_WRITE;
-    extern const int CHECKSUM_DOESNT_MATCH;
     extern const int UNEXPECTED_ZOOKEEPER_ERROR;
     extern const int NO_ZOOKEEPER;
     extern const int READONLY;
     extern const int UNKNOWN_STATUS_OF_INSERT;
     extern const int INSERT_WAS_DEDUPLICATED;
-    extern const int KEEPER_EXCEPTION;
     extern const int TIMEOUT_EXCEEDED;
     extern const int NO_ACTIVE_REPLICAS;
 }
diff --git a/dbms/src/Storages/MergeTree/ReplicatedMergeTreeLogEntry.h b/dbms/src/Storages/MergeTree/ReplicatedMergeTreeLogEntry.h
index d761e958828..922d86e983d 100644
--- a/dbms/src/Storages/MergeTree/ReplicatedMergeTreeLogEntry.h
+++ b/dbms/src/Storages/MergeTree/ReplicatedMergeTreeLogEntry.h
@@ -20,8 +20,6 @@ class ReplicatedMergeTreeQueue;
 namespace ErrorCodes
 {
     extern const int LOGICAL_ERROR;
-    extern const int UNKNOWN_FORMAT_VERSION;
-    extern const int CANNOT_PARSE_TEXT;
 }
 
 
diff --git a/dbms/src/Storages/MergeTree/ReplicatedMergeTreeQueue.cpp b/dbms/src/Storages/MergeTree/ReplicatedMergeTreeQueue.cpp
index 03c842babc0..c4cd79977e1 100644
--- a/dbms/src/Storages/MergeTree/ReplicatedMergeTreeQueue.cpp
+++ b/dbms/src/Storages/MergeTree/ReplicatedMergeTreeQueue.cpp
@@ -15,7 +15,6 @@ namespace ErrorCodes
 {
     extern const int UNEXPECTED_NODE_IN_ZOOKEEPER;
     extern const int UNFINISHED;
-    extern const int PART_IS_TEMPORARILY_LOCKED;
 }
 
 
diff --git a/dbms/src/Storages/StorageDistributed.cpp b/dbms/src/Storages/StorageDistributed.cpp
index 96420485896..bf8cd234a0a 100644
--- a/dbms/src/Storages/StorageDistributed.cpp
+++ b/dbms/src/Storages/StorageDistributed.cpp
@@ -64,7 +64,6 @@ namespace ErrorCodes
 {
     extern const int STORAGE_REQUIRES_PARAMETER;
     extern const int BAD_ARGUMENTS;
-    extern const int READONLY;
     extern const int NUMBER_OF_ARGUMENTS_DOESNT_MATCH;
     extern const int INCORRECT_NUMBER_OF_COLUMNS;
     extern const int INFINITE_LOOP;
diff --git a/dbms/src/Storages/StorageFile.cpp b/dbms/src/Storages/StorageFile.cpp
index a6dfa6e4adc..f3958e54320 100644
--- a/dbms/src/Storages/StorageFile.cpp
+++ b/dbms/src/Storages/StorageFile.cpp
@@ -43,7 +43,6 @@ namespace DB
 
 namespace ErrorCodes
 {
-    extern const int CANNOT_WRITE_TO_FILE_DESCRIPTOR;
     extern const int CANNOT_SEEK_THROUGH_FILE;
     extern const int CANNOT_TRUNCATE_FILE;
     extern const int DATABASE_ACCESS_DENIED;
@@ -51,7 +50,6 @@ namespace ErrorCodes
     extern const int UNKNOWN_IDENTIFIER;
     extern const int INCORRECT_FILE_NAME;
     extern const int FILE_DOESNT_EXIST;
-    extern const int EMPTY_LIST_OF_COLUMNS_PASSED;
 }
 
 namespace
diff --git a/dbms/src/Storages/StorageHDFS.cpp b/dbms/src/Storages/StorageHDFS.cpp
index 655234b49b6..bdd4ba6a9b2 100644
--- a/dbms/src/Storages/StorageHDFS.cpp
+++ b/dbms/src/Storages/StorageHDFS.cpp
@@ -33,8 +33,6 @@ namespace DB
 namespace ErrorCodes
 {
     extern const int NUMBER_OF_ARGUMENTS_DOESNT_MATCH;
-    extern const int NOT_IMPLEMENTED;
-    extern const int BAD_ARGUMENTS;
 }
 
 StorageHDFS::StorageHDFS(const String & uri_,
diff --git a/dbms/src/Storages/StorageLog.cpp b/dbms/src/Storages/StorageLog.cpp
index cf5f41204c7..20def7d1b1d 100644
--- a/dbms/src/Storages/StorageLog.cpp
+++ b/dbms/src/Storages/StorageLog.cpp
@@ -38,8 +38,6 @@ namespace DB
 namespace ErrorCodes
 {
     extern const int LOGICAL_ERROR;
-    extern const int EMPTY_LIST_OF_COLUMNS_PASSED;
-    extern const int NO_SUCH_COLUMN_IN_TABLE;
     extern const int DUPLICATE_COLUMN;
     extern const int SIZES_OF_MARKS_FILES_ARE_INCONSISTENT;
     extern const int NUMBER_OF_ARGUMENTS_DOESNT_MATCH;
diff --git a/dbms/src/Storages/StorageMaterializedView.cpp b/dbms/src/Storages/StorageMaterializedView.cpp
index dd3ba02ea8e..46c8f0c71c6 100644
--- a/dbms/src/Storages/StorageMaterializedView.cpp
+++ b/dbms/src/Storages/StorageMaterializedView.cpp
@@ -31,7 +31,6 @@ namespace ErrorCodes
     extern const int LOGICAL_ERROR;
     extern const int INCORRECT_QUERY;
     extern const int QUERY_IS_NOT_SUPPORTED_IN_MATERIALIZED_VIEW;
-    extern const int QUERY_IS_NOT_SUPPORTED_IN_LIVE_VIEW;
 }
 
 static inline String generateInnerTableName(const String & table_name)
diff --git a/dbms/src/Storages/StorageMerge.cpp b/dbms/src/Storages/StorageMerge.cpp
index 654289b2d96..c9b2a63afca 100644
--- a/dbms/src/Storages/StorageMerge.cpp
+++ b/dbms/src/Storages/StorageMerge.cpp
@@ -39,7 +39,6 @@ namespace ErrorCodes
 {
     extern const int ILLEGAL_PREWHERE;
     extern const int NUMBER_OF_ARGUMENTS_DOESNT_MATCH;
-    extern const int NO_SUCH_COLUMN_IN_TABLE;
     extern const int BLOCKS_HAVE_DIFFERENT_STRUCTURE;
     extern const int SAMPLING_NOT_SUPPORTED;
 }
diff --git a/dbms/src/Storages/StorageMergeTree.cpp b/dbms/src/Storages/StorageMergeTree.cpp
index c89648c38ac..bee36327130 100644
--- a/dbms/src/Storages/StorageMergeTree.cpp
+++ b/dbms/src/Storages/StorageMergeTree.cpp
@@ -36,12 +36,7 @@ namespace ErrorCodes
     extern const int ABORTED;
     extern const int BAD_ARGUMENTS;
     extern const int INCORRECT_DATA;
-    extern const int INCORRECT_FILE_NAME;
     extern const int CANNOT_ASSIGN_OPTIMIZE;
-    extern const int INCOMPATIBLE_COLUMNS;
-    extern const int PART_IS_TEMPORARILY_LOCKED;
-    extern const int UNKNOWN_SETTING;
-    extern const int TOO_BIG_AST;
 }
 
 namespace ActionLocks
diff --git a/dbms/src/Storages/StorageReplicatedMergeTree.cpp b/dbms/src/Storages/StorageReplicatedMergeTree.cpp
index c81986c02ac..7b754c64175 100644
--- a/dbms/src/Storages/StorageReplicatedMergeTree.cpp
+++ b/dbms/src/Storages/StorageReplicatedMergeTree.cpp
@@ -84,7 +84,6 @@ namespace ErrorCodes
     extern const int INCORRECT_DATA;
     extern const int INCOMPATIBLE_COLUMNS;
     extern const int REPLICA_IS_ALREADY_EXIST;
-    extern const int NO_SUCH_REPLICA;
     extern const int NO_REPLICA_HAS_PART;
     extern const int LOGICAL_ERROR;
     extern const int TOO_MANY_UNEXPECTED_DATA_PARTS;
@@ -99,16 +98,11 @@ namespace ErrorCodes
     extern const int TOO_MANY_RETRIES_TO_FETCH_PARTS;
     extern const int RECEIVED_ERROR_FROM_REMOTE_IO_SERVER;
     extern const int PARTITION_DOESNT_EXIST;
-    extern const int CHECKSUM_DOESNT_MATCH;
-    extern const int BAD_SIZE_OF_FILE_IN_DATA_PART;
-    extern const int UNEXPECTED_FILE_IN_DATA_PART;
-    extern const int NO_FILE_IN_DATA_PART;
     extern const int UNFINISHED;
     extern const int RECEIVED_ERROR_TOO_MANY_REQUESTS;
     extern const int TOO_MANY_FETCHES;
     extern const int BAD_DATA_PART_NAME;
     extern const int PART_IS_TEMPORARILY_LOCKED;
-    extern const int INCORRECT_FILE_NAME;
     extern const int CANNOT_ASSIGN_OPTIMIZE;
     extern const int KEEPER_EXCEPTION;
     extern const int ALL_REPLICAS_LOST;
diff --git a/dbms/src/Storages/StorageReplicatedMergeTree.h b/dbms/src/Storages/StorageReplicatedMergeTree.h
index cc8cb16127e..a6b1ac7d73c 100644
--- a/dbms/src/Storages/StorageReplicatedMergeTree.h
+++ b/dbms/src/Storages/StorageReplicatedMergeTree.h
@@ -555,6 +555,5 @@ protected:
 };
 
 
-extern const int MAX_AGE_OF_LOCAL_PART_THAT_WASNT_ADDED_TO_ZOOKEEPER;
 
 }
diff --git a/dbms/src/Storages/StorageStripeLog.cpp b/dbms/src/Storages/StorageStripeLog.cpp
index bb18cc7e77e..445c16d73de 100644
--- a/dbms/src/Storages/StorageStripeLog.cpp
+++ b/dbms/src/Storages/StorageStripeLog.cpp
@@ -43,11 +43,8 @@ namespace DB
 
 namespace ErrorCodes
 {
-    extern const int EMPTY_LIST_OF_COLUMNS_PASSED;
-    extern const int CANNOT_CREATE_DIRECTORY;
     extern const int NUMBER_OF_ARGUMENTS_DOESNT_MATCH;
     extern const int INCORRECT_FILE_NAME;
-    extern const int LOGICAL_ERROR;
 }
 
 
diff --git a/dbms/src/Storages/StorageTinyLog.cpp b/dbms/src/Storages/StorageTinyLog.cpp
index 85a1925cdac..f171c694f21 100644
--- a/dbms/src/Storages/StorageTinyLog.cpp
+++ b/dbms/src/Storages/StorageTinyLog.cpp
@@ -45,11 +45,7 @@ namespace DB
 
 namespace ErrorCodes
 {
-    extern const int EMPTY_LIST_OF_COLUMNS_PASSED;
-    extern const int CANNOT_CREATE_DIRECTORY;
-    extern const int CANNOT_READ_ALL_DATA;
     extern const int DUPLICATE_COLUMN;
-    extern const int LOGICAL_ERROR;
     extern const int INCORRECT_FILE_NAME;
     extern const int NUMBER_OF_ARGUMENTS_DOESNT_MATCH;
 }
diff --git a/dbms/src/Storages/StorageURL.cpp b/dbms/src/Storages/StorageURL.cpp
index 2d9a58030b1..aaccccebef3 100644
--- a/dbms/src/Storages/StorageURL.cpp
+++ b/dbms/src/Storages/StorageURL.cpp
@@ -26,7 +26,6 @@ namespace DB
 namespace ErrorCodes
 {
     extern const int NUMBER_OF_ARGUMENTS_DOESNT_MATCH;
-    extern const int UNACCEPTABLE_URL;
 }
 
 IStorageURLBase::IStorageURLBase(
diff --git a/dbms/src/Storages/System/StorageSystemColumns.cpp b/dbms/src/Storages/System/StorageSystemColumns.cpp
index 5943435464e..2d97d0af1b9 100644
--- a/dbms/src/Storages/System/StorageSystemColumns.cpp
+++ b/dbms/src/Storages/System/StorageSystemColumns.cpp
@@ -19,7 +19,6 @@ namespace DB
 
 namespace ErrorCodes
 {
-    extern const int LOGICAL_ERROR;
     extern const int TABLE_IS_DROPPED;
 }
 
diff --git a/dbms/src/Storages/System/StorageSystemTables.cpp b/dbms/src/Storages/System/StorageSystemTables.cpp
index f2b7d354226..ef4cbbed325 100644
--- a/dbms/src/Storages/System/StorageSystemTables.cpp
+++ b/dbms/src/Storages/System/StorageSystemTables.cpp
@@ -24,7 +24,6 @@ namespace DB
 
 namespace ErrorCodes
 {
-    extern const int CANNOT_GET_CREATE_TABLE_QUERY;
     extern const int TABLE_IS_DROPPED;
 }
 
diff --git a/dbms/src/Storages/getStructureOfRemoteTable.cpp b/dbms/src/Storages/getStructureOfRemoteTable.cpp
index 2b6924695bf..731cbb5fee7 100644
--- a/dbms/src/Storages/getStructureOfRemoteTable.cpp
+++ b/dbms/src/Storages/getStructureOfRemoteTable.cpp
@@ -20,7 +20,6 @@ namespace DB
 
 namespace ErrorCodes
 {
-    extern const int NO_REMOTE_SHARD_FOUND;
 }
 
 
diff --git a/dbms/src/TableFunctions/TableFunctionFactory.cpp b/dbms/src/TableFunctions/TableFunctionFactory.cpp
index e9e459a09da..1b34c1a1e6f 100644
--- a/dbms/src/TableFunctions/TableFunctionFactory.cpp
+++ b/dbms/src/TableFunctions/TableFunctionFactory.cpp
@@ -10,7 +10,6 @@ namespace DB
 
 namespace ErrorCodes
 {
-    extern const int READONLY;
     extern const int UNKNOWN_FUNCTION;
     extern const int LOGICAL_ERROR;
 }
diff --git a/utils/check-style/check-style b/utils/check-style/check-style
index 6848b8510de..ce6eb9dde23 100755
--- a/utils/check-style/check-style
+++ b/utils/check-style/check-style
@@ -32,3 +32,13 @@ find -L $ROOT_PATH -type l 2>/dev/null | grep -v contrib && echo "^ Broken symli
 
 # Double whitespaces
 find $ROOT_PATH/{dbms,base} -name '*.h' -or -name '*.cpp' 2>/dev/null | while read i; do $ROOT_PATH/utils/check-style/double-whitespaces.pl < $i || echo -e "^ File $i contains double whitespaces\n"; done
+
+# Unused ErrorCodes
+# NOTE: to fix automatically, replace echo with sed -i "/extern const int $code/d" $file
+find $ROOT_PATH/{dbms,base} -name '*.h' -or -name '*.cpp' | xargs grep -l -P 'extern const int [_A-Z]+' | while read file; do grep -P 'extern const int [_A-Z]+;' $file | sed -r -e 's/^.*?extern const int ([_A-Z]+);.*?$/\1/' | while read code; do grep -q "ErrorCodes::$code" $file || echo "ErrorCode $code is defined but not used in file $file"; done; done
+
+# Undefined ErrorCodes
+find $ROOT_PATH/{dbms,base} -name '*.h' -or -name '*.cpp' | xargs grep -l -P 'ErrorCodes::[_A-Z]+' | while read file; do grep -P 'ErrorCodes::[_A-Z]+' $file | sed -r -e 's/^.*?ErrorCodes::([_A-Z]+).*?$/\1/' | while read code; do grep -q "extern const int $code" $file || echo "ErrorCode $code is used in file $file but not defined"; done; done
+
+# Duplicate ErrorCodes
+find $ROOT_PATH/{dbms,base} -name '*.h' -or -name '*.cpp' | xargs grep -l -P 'ErrorCodes::[_A-Z]+' | while read file; do grep -P 'extern const int [_A-Z]+;' $file | sort | uniq -c | grep -v -P ' +1 ' && echo "Duplicate ErrorCode in file $file"; done