fix

src/IO/BrotliWriteBuffer.cpp

@@ -74,7 +74,7 @@ void BrotliWriteBuffer::finalizeBefore()
     next();
 
     /// Don't write out if no data was ever compressed
-    if (total_out == 0)
+    if (!compress_empty && total_out == 0)
         return;
 
     while (true)

src/IO/BrotliWriteBuffer.h

@@ -22,13 +22,15 @@ public:
         int compression_level,
         size_t buf_size = DBMS_DEFAULT_BUFFER_SIZE,
         char * existing_memory = nullptr,
-        size_t alignment = 0)
+        size_t alignment = 0,
+        bool compress_empty_ = true)
     : WriteBufferWithOwnMemoryDecorator(std::move(out_), buf_size, existing_memory, alignment)
     , brotli(std::make_unique<BrotliStateWrapper>())
     , in_available(0)
     , in_data(nullptr)
     , out_capacity(0)
     , out_data(nullptr)
+    , compress_empty(compress_empty_)
     {
         BrotliEncoderSetParameter(brotli->state, BROTLI_PARAM_QUALITY, static_cast<uint32_t>(compression_level));
         // Set LZ77 window size. According to brotli sources default value is 24 (c/tools/brotli.c:81)
@@ -62,6 +64,7 @@ private:
 
 protected:
     size_t total_out = 0;
+    bool compress_empty = true;
 };
 
 }

src/IO/Bzip2WriteBuffer.cpp

@@ -79,7 +79,7 @@ void Bzip2WriteBuffer::finalizeBefore()
     next();
 
     /// Don't write out if no data was ever compressed
-    if (bz->stream.total_out_hi32 == 0 && bz->stream.total_out_lo32 == 0)
+    if (!compress_empty && bz->stream.total_out_hi32 == 0 && bz->stream.total_out_lo32 == 0)
         return;
 
     out->nextIfAtEnd();

src/IO/Bzip2WriteBuffer.h

@@ -21,9 +21,10 @@ public:
         int compression_level,
         size_t buf_size = DBMS_DEFAULT_BUFFER_SIZE,
         char * existing_memory = nullptr,
-        size_t alignment = 0)
-    : WriteBufferWithOwnMemoryDecorator(std::move(out_), buf_size, existing_memory, alignment)
-    , bz(std::make_unique<Bzip2StateWrapper>(compression_level))
+        size_t alignment = 0,
+        bool compress_empty_ = true)
+    : WriteBufferWithOwnMemoryDecorator(std::move(out_), buf_size, existing_memory, alignment), bz(std::make_unique<Bzip2StateWrapper>(compression_level))
+    , compress_empty(compress_empty_)
     {
     }
 
@@ -44,6 +45,7 @@ private:
     };
 
     std::unique_ptr<Bzip2StateWrapper> bz;
+    bool compress_empty = true;
 };
 
 }

src/IO/CompressionMethod.cpp

@@ -172,27 +172,27 @@ std::unique_ptr<ReadBuffer> wrapReadBufferWithCompressionMethod(
 
 template<typename WriteBufferT>
 std::unique_ptr<WriteBuffer> createWriteCompressedWrapper(
-    WriteBufferT && nested, CompressionMethod method, int level, size_t buf_size, char * existing_memory, size_t alignment)
+    WriteBufferT && nested, CompressionMethod method, int level, size_t buf_size, char * existing_memory, size_t alignment, bool compress_empty)
 {
     if (method == DB::CompressionMethod::Gzip || method == CompressionMethod::Zlib)
-        return std::make_unique<ZlibDeflatingWriteBuffer>(std::forward<WriteBufferT>(nested), method, level, buf_size, existing_memory, alignment);
+        return std::make_unique<ZlibDeflatingWriteBuffer>(std::forward<WriteBufferT>(nested), method, level, buf_size, existing_memory, alignment, compress_empty);
 
 #if USE_BROTLI
     if (method == DB::CompressionMethod::Brotli)
-        return std::make_unique<BrotliWriteBuffer>(std::forward<WriteBufferT>(nested), level, buf_size, existing_memory, alignment);
+        return std::make_unique<BrotliWriteBuffer>(std::forward<WriteBufferT>(nested), level, buf_size, existing_memory, alignment, compress_empty);
 #endif
     if (method == CompressionMethod::Xz)
-        return std::make_unique<LZMADeflatingWriteBuffer>(std::forward<WriteBufferT>(nested), level, buf_size, existing_memory, alignment);
+        return std::make_unique<LZMADeflatingWriteBuffer>(std::forward<WriteBufferT>(nested), level, buf_size, existing_memory, alignment, compress_empty);
 
     if (method == CompressionMethod::Zstd)
-        return std::make_unique<ZstdDeflatingWriteBuffer>(std::forward<WriteBufferT>(nested), level, buf_size, existing_memory, alignment);
+        return std::make_unique<ZstdDeflatingWriteBuffer>(std::forward<WriteBufferT>(nested), level, buf_size, existing_memory, alignment, compress_empty);
 
     if (method == CompressionMethod::Lz4)
-        return std::make_unique<Lz4DeflatingWriteBuffer>(std::forward<WriteBufferT>(nested), level, buf_size, existing_memory, alignment);
+        return std::make_unique<Lz4DeflatingWriteBuffer>(std::forward<WriteBufferT>(nested), level, buf_size, existing_memory, alignment, compress_empty);
 
 #if USE_BZIP2
     if (method == CompressionMethod::Bzip2)
-        return std::make_unique<Bzip2WriteBuffer>(std::forward<WriteBufferT>(nested), level, buf_size, existing_memory, alignment);
+        return std::make_unique<Bzip2WriteBuffer>(std::forward<WriteBufferT>(nested), level, buf_size, existing_memory, alignment, compress_empty);
 #endif
 #if USE_SNAPPY
     if (method == CompressionMethod::Snappy)
@@ -209,11 +209,12 @@ std::unique_ptr<WriteBuffer> wrapWriteBufferWithCompressionMethod(
     int level,
     size_t buf_size,
     char * existing_memory,
-    size_t alignment)
+    size_t alignment,
+    bool compress_empty)
 {
     if (method == CompressionMethod::None)
         return nested;
-    return createWriteCompressedWrapper(nested, method, level, buf_size, existing_memory, alignment);
+    return createWriteCompressedWrapper(nested, method, level, buf_size, existing_memory, alignment, compress_empty);
 }
 
 
@@ -223,10 +224,11 @@ std::unique_ptr<WriteBuffer> wrapWriteBufferWithCompressionMethod(
     int level,
     size_t buf_size,
     char * existing_memory,
-    size_t alignment)
+    size_t alignment,
+    bool compress_empty)
 {
     assert(method != CompressionMethod::None);
-    return createWriteCompressedWrapper(nested, method, level, buf_size, existing_memory, alignment);
+    return createWriteCompressedWrapper(nested, method, level, buf_size, existing_memory, alignment, compress_empty);
 }
 
 }

src/IO/CompressionMethod.h

@@ -79,7 +79,8 @@ std::unique_ptr<WriteBuffer> wrapWriteBufferWithCompressionMethod(
     int level,
     size_t buf_size = DBMS_DEFAULT_BUFFER_SIZE,
     char * existing_memory = nullptr,
-    size_t alignment = 0);
+    size_t alignment = 0,
+    bool compress_empty = true);
 
 std::unique_ptr<WriteBuffer> wrapWriteBufferWithCompressionMethod(
     WriteBuffer * nested,
@@ -87,6 +88,7 @@ std::unique_ptr<WriteBuffer> wrapWriteBufferWithCompressionMethod(
     int level,
     size_t buf_size = DBMS_DEFAULT_BUFFER_SIZE,
     char * existing_memory = nullptr,
-    size_t alignment = 0);
+    size_t alignment = 0,
+    bool compress_empty = true);
 
 }

src/IO/LZMADeflatingWriteBuffer.cpp

@@ -93,7 +93,7 @@ void LZMADeflatingWriteBuffer::finalizeBefore()
     next();
 
     /// Don't write out if no data was ever compressed
-    if (lstr.total_out)
+    if (!compress_empty && lstr.total_out == 0)
         return;
 
     do

src/IO/LZMADeflatingWriteBuffer.h

@@ -20,8 +20,9 @@ public:
         int compression_level,
         size_t buf_size = DBMS_DEFAULT_BUFFER_SIZE,
         char * existing_memory = nullptr,
-        size_t alignment = 0)
-    : WriteBufferWithOwnMemoryDecorator(std::move(out_), buf_size, existing_memory, alignment)
+        size_t alignment = 0,
+        bool compress_empty_ = true)
+    : WriteBufferWithOwnMemoryDecorator(std::move(out_), buf_size, existing_memory, alignment), compress_empty(compress_empty_)
     {
         initialize(compression_level);
     }
@@ -37,6 +38,8 @@ private:
     void finalizeAfter() override;
 
     lzma_stream lstr;
+
+    bool compress_empty = true;
 };
 
 }

src/IO/Lz4DeflatingWriteBuffer.cpp

@@ -128,7 +128,7 @@ void Lz4DeflatingWriteBuffer::finalizeBefore()
     next();
 
     /// Don't write out if no data was ever compressed
-    if (first_time)
+    if (!compress_empty && first_time)
         return;
 
     out_capacity = out->buffer().end() - out->position();

src/IO/Lz4DeflatingWriteBuffer.h

@@ -20,12 +20,14 @@ public:
         int compression_level,
         size_t buf_size = DBMS_DEFAULT_BUFFER_SIZE,
         char * existing_memory = nullptr,
-        size_t alignment = 0)
+        size_t alignment = 0,
+        bool compress_empty_ = true)
     : WriteBufferWithOwnMemoryDecorator(std::move(out_), buf_size, existing_memory, alignment)
     , in_data(nullptr)
     , out_data(nullptr)
     , in_capacity(0)
     , out_capacity(0)
+    , compress_empty(compress_empty_)
     {
         initialize(compression_level);
     }
@@ -50,5 +52,6 @@ private:
     size_t out_capacity;
 
     bool first_time = true;
+    bool compress_empty = true;
 };
 }

src/IO/ZlibDeflatingWriteBuffer.cpp

@@ -53,7 +53,7 @@ void ZlibDeflatingWriteBuffer::finalizeBefore()
     next();
 
     /// Don't write out if no data was ever compressed
-    if (zstr.total_out == 0)
+    if (!compress_empty && zstr.total_out == 0)
         return;
 
     /// https://github.com/zlib-ng/zlib-ng/issues/494

src/IO/ZlibDeflatingWriteBuffer.h

@@ -28,8 +28,9 @@ public:
             int compression_level,
             size_t buf_size = DBMS_DEFAULT_BUFFER_SIZE,
             char * existing_memory = nullptr,
-            size_t alignment = 0)
-    : WriteBufferWithOwnMemoryDecorator(std::move(out_), buf_size, existing_memory, alignment)
+            size_t alignment = 0,
+            bool compress_empty_ = true)
+    : WriteBufferWithOwnMemoryDecorator(std::move(out_), buf_size, existing_memory, alignment), compress_empty(compress_empty_)
     {
         zstr.zalloc = nullptr;
         zstr.zfree = nullptr;
@@ -63,6 +64,7 @@ private:
     virtual void finalizeAfter() override;
 
     z_stream zstr;
+    bool compress_empty = true;
 };
 
 }

src/IO/ZstdDeflatingWriteBuffer.cpp

@@ -86,7 +86,7 @@ void ZstdDeflatingWriteBuffer::nextImpl()
 void ZstdDeflatingWriteBuffer::finalizeBefore()
 {
     /// Don't write out if no data was ever compressed
-    if (total_out == 0)
+    if (!compress_empty && total_out == 0)
         return;
     flush(ZSTD_e_end);
 }

src/IO/ZstdDeflatingWriteBuffer.h

@@ -20,8 +20,9 @@ public:
         int compression_level,
         size_t buf_size = DBMS_DEFAULT_BUFFER_SIZE,
         char * existing_memory = nullptr,
-        size_t alignment = 0)
-    : WriteBufferWithOwnMemoryDecorator(std::move(out_), buf_size, existing_memory, alignment)
+        size_t alignment = 0,
+        bool compress_empty_ = true)
+    : WriteBufferWithOwnMemoryDecorator(std::move(out_), buf_size, existing_memory, alignment), compress_empty(compress_empty_)
     {
         initialize(compression_level);
     }
@@ -51,6 +52,7 @@ private:
     ZSTD_outBuffer output;
 
     size_t total_out = 0;
+    bool compress_empty = true;
 };
 
 }

src/Server/HTTPHandler.cpp

@@ -630,7 +630,12 @@ void HTTPHandler::processQuery(
     if (client_supports_http_compression && enable_http_compression)
     {
         used_output.out_holder->setCompressionMethodHeader(http_response_compression_method);
-        used_output.wrap_compressed_holder = wrapWriteBufferWithCompressionMethod(used_output.out_holder.get(), http_response_compression_method, static_cast<int>(http_zlib_compression_level));
+        used_output.wrap_compressed_holder =
+            wrapWriteBufferWithCompressionMethod(
+                used_output.out_holder.get(),
+                http_response_compression_method,
+                static_cast<int>(http_zlib_compression_level),
+                DBMS_DEFAULT_BUFFER_SIZE, nullptr, 0, false);
         used_output.out = used_output.wrap_compressed_holder;
     }
     else