Reduce memory usage of inserts to JSON by using adaptive write buffer size

src/Compression/CompressedWriteBuffer.cpp

@@ -55,10 +55,29 @@ void CompressedWriteBuffer::nextImpl()
 
         out.write(compressed_buffer.data(), compressed_size);
     }
+
+    /// Increase buffer size for next data if adaptive buffer size is used and nextImpl was called because of end of buffer.
+    if (!available() && use_adaptive_buffer_size && memory.size() < adaptive_buffer_max_size)
+    {
+        memory.resize(std::min(memory.size() * 2, adaptive_buffer_max_size));
+        BufferBase::set(memory.data(), memory.size(), 0);
+    }
 }
 
-CompressedWriteBuffer::CompressedWriteBuffer(WriteBuffer & out_, CompressionCodecPtr codec_, size_t buf_size)
+void CompressedWriteBuffer::finalizeImpl()
-    : BufferWithOwnMemory<WriteBuffer>(buf_size), out(out_), codec(std::move(codec_))
+{
+    /// Don't try to resize buffer in nextImpl.
+    use_adaptive_buffer_size = false;
+    next();
+}
+
+CompressedWriteBuffer::CompressedWriteBuffer(
+    WriteBuffer & out_, CompressionCodecPtr codec_, size_t buf_size, bool use_adaptive_buffer_size_, size_t adaptive_buffer_initial_size)
+    : BufferWithOwnMemory<WriteBuffer>(use_adaptive_buffer_size_ ? adaptive_buffer_initial_size : buf_size)
+    , out(out_)
+    , codec(std::move(codec_))
+    , use_adaptive_buffer_size(use_adaptive_buffer_size_)
+    , adaptive_buffer_max_size(buf_size)
 {
 }
 

src/Compression/CompressedWriteBuffer.h

@@ -19,7 +19,9 @@ public:
     explicit CompressedWriteBuffer(
         WriteBuffer & out_,
         CompressionCodecPtr codec_ = CompressionCodecFactory::instance().getDefaultCodec(),
-        size_t buf_size = DBMS_DEFAULT_BUFFER_SIZE);
+        size_t buf_size = DBMS_DEFAULT_BUFFER_SIZE,
+        bool use_adaptive_buffer_size_ = false,
+        size_t adaptive_buffer_initial_size = DBMS_DEFAULT_INITIAL_ADAPTIVE_BUFFER_SIZE);
 
     ~CompressedWriteBuffer() override;
 
@@ -45,10 +47,17 @@ public:
 
 private:
     void nextImpl() override;
+    void finalizeImpl() override;
 
     WriteBuffer & out;
     CompressionCodecPtr codec;
 
+    /// If true, the size of internal buffer will be exponentially increased up to
+    /// adaptive_buffer_max_size after each nextImpl call. It can be used to avoid
+    /// large buffer allocation when actual size of writen data is small.
+    bool use_adaptive_buffer_size;
+    size_t adaptive_buffer_max_size;
+
     PODArray<char> compressed_buffer;
 };
 

src/Core/Defines.h

@@ -20,6 +20,9 @@ static constexpr auto DBMS_DEFAULT_POLL_INTERVAL = 10;
 /// The size of the I/O buffer by default.
 static constexpr auto DBMS_DEFAULT_BUFFER_SIZE = 1048576ULL;
 
+/// The initial size of adaptive I/O buffer by default.
+static constexpr auto DBMS_DEFAULT_INITIAL_ADAPTIVE_BUFFER_SIZE = 16384ULL;
+
 static constexpr auto PADDING_FOR_SIMD = 64;
 
 /** Which blocks by default read the data (by number of rows).

src/DataTypes/Serializations/ISerialization.cpp

@@ -420,6 +420,20 @@ bool ISerialization::isEphemeralSubcolumn(const DB::ISerialization::SubstreamPat
     return path[last_elem].type == Substream::VariantElementNullMap;
 }
 
+bool ISerialization::isDynamicSubcolumn(const DB::ISerialization::SubstreamPath & path, size_t prefix_len)
+{
+    if (prefix_len == 0 || prefix_len > path.size())
+        return false;
+
+    for (size_t i = 0; i != prefix_len; ++i)
+    {
+        if (path[i].type == SubstreamType::DynamicData || path[i].type == SubstreamType::ObjectData)
+            return true;
+    }
+
+    return false;
+}
+
 ISerialization::SubstreamData ISerialization::createFromPath(const SubstreamPath & path, size_t prefix_len)
 {
     assert(prefix_len <= path.size());

src/DataTypes/Serializations/ISerialization.h

@@ -457,6 +457,9 @@ public:
     /// for writing/reading data. For example, it's a null-map subcolumn of Variant type (it's always constructed from discriminators);.
     static bool isEphemeralSubcolumn(const SubstreamPath & path, size_t prefix_len);
 
+    /// Returns true if stream with specified path corresponds to dynamic subcolumn.
+    static bool isDynamicSubcolumn(const SubstreamPath & path, size_t prefix_len);
+
 protected:
     template <typename State, typename StatePtr>
     State * checkAndGetState(const StatePtr & state) const;

src/Disks/DiskLocal.cpp

@@ -23,6 +23,8 @@
 #include <Common/randomSeed.h>
 #include <IO/ReadHelpers.h>
 #include <IO/WriteHelpers.h>
+#include <IO/AdaptiveWriteBufferFromFile.h>
+#include <IO/AdaptiveWriteBuffer.h>
 #include <Common/logger_useful.h>
 
 
@@ -339,7 +341,15 @@ DiskLocal::writeFile(const String & path, size_t buf_size, WriteMode mode, const
 {
     int flags = (mode == WriteMode::Append) ? (O_APPEND | O_CREAT | O_WRONLY) : -1;
     return std::make_unique<WriteBufferFromFile>(
-        fs::path(disk_path) / path, buf_size, flags, settings.local_throttler);
+        fs::path(disk_path) / path,
+        buf_size,
+        flags,
+        settings.local_throttler,
+        0666,
+        nullptr,
+        0,
+        settings.use_adaptive_write_buffer,
+        settings.adaptive_write_buffer_initial_size);
 }
 
 std::vector<String> DiskLocal::getBlobPath(const String & path) const

src/Disks/IO/WriteBufferFromAzureBlobStorage.cpp

@@ -251,12 +251,29 @@ void WriteBufferFromAzureBlobStorage::allocateBuffer()
     auto size = buffer_allocation_policy->getBufferSize();
 
     if (buffer_allocation_policy->getBufferNumber() == 1)
-        size = std::min(size_t(DBMS_DEFAULT_BUFFER_SIZE), size);
+    {
+        allocateFirstBuffer();
+        return;
+    }
 
     memory = Memory(size);
     WriteBuffer::set(memory.data(), memory.size());
 }
 
+void WriteBufferFromAzureBlobStorage::allocateFirstBuffer()
+{
+    /// First buffer was already allocated in BufferWithOwnMemory constructor with buffer size provided in constructor.
+    /// It will be reallocated in subsequent nextImpl calls up to the desired buffer size from buffer_allocation_policy.
+    /// But it may happen that buffer size provided in constructor is larger then desired buffer size from buffer_allocation_policy.
+    /// Resize memory in this case to the desired size.
+    const auto max_first_buffer = buffer_allocation_policy->getBufferSize();
+    if (memory.size() > max_first_buffer)
+    {
+        memory.resize(max_first_buffer);
+        WriteBuffer::set(memory.data(), memory.size());
+    }
+}
+
 void WriteBufferFromAzureBlobStorage::detachBuffer()
 {
     size_t data_size = size_t(position() - memory.data());

src/Disks/IO/WriteBufferFromAzureBlobStorage.h

@@ -53,6 +53,7 @@ private:
     void detachBuffer();
     void reallocateFirstBuffer();
     void allocateBuffer();
+    void allocateFirstBuffer();
     void hidePartialData();
     void setFakeBufferWhenPreFinalized();
 

src/Disks/ObjectStorages/S3/S3ObjectStorage.cpp

@@ -282,7 +282,7 @@ std::unique_ptr<WriteBufferFromFileBase> S3ObjectStorage::writeObject( /// NOLIN
         client.get(),
         uri.bucket,
         object.remote_path,
-        buf_size,
+        write_settings.use_adaptive_write_buffer ? write_settings.adaptive_write_buffer_initial_size : buf_size,
         request_settings,
         std::move(blob_storage_log),
         attributes,

src/IO/WriteBufferFromFile.cpp

@@ -32,8 +32,10 @@ WriteBufferFromFile::WriteBufferFromFile(
     ThrottlerPtr throttler_,
     mode_t mode,
     char * existing_memory,
-    size_t alignment)
+    size_t alignment,
-    : WriteBufferFromFileDescriptor(-1, buf_size, existing_memory, throttler_, alignment, file_name_)
+    bool use_adaptive_buffer_size_,
+    size_t adaptive_buffer_initial_size)
+    : WriteBufferFromFileDescriptor(-1, buf_size, existing_memory, throttler_, alignment, file_name_, use_adaptive_buffer_size_, adaptive_buffer_initial_size)
 {
     ProfileEvents::increment(ProfileEvents::FileOpen);
 
@@ -66,8 +68,10 @@ WriteBufferFromFile::WriteBufferFromFile(
     size_t buf_size,
     ThrottlerPtr throttler_,
     char * existing_memory,
-    size_t alignment)
+    size_t alignment,
-    : WriteBufferFromFileDescriptor(fd_, buf_size, existing_memory, throttler_, alignment, original_file_name)
+    bool use_adaptive_buffer_size_,
+    size_t adaptive_buffer_initial_size)
+    : WriteBufferFromFileDescriptor(fd_, buf_size, existing_memory, throttler_, alignment, original_file_name, use_adaptive_buffer_size_, adaptive_buffer_initial_size)
 {
     fd_ = -1;
 }

src/IO/WriteBufferFromFile.h

@@ -36,7 +36,9 @@ public:
         ThrottlerPtr throttler_ = {},
         mode_t mode = 0666,
         char * existing_memory = nullptr,
-        size_t alignment = 0);
+        size_t alignment = 0,
+        bool use_adaptive_buffer_size_ = false,
+        size_t adaptive_buffer_initial_size = DBMS_DEFAULT_INITIAL_ADAPTIVE_BUFFER_SIZE);
 
     /// Use pre-opened file descriptor.
     explicit WriteBufferFromFile(
@@ -45,7 +47,9 @@ public:
         size_t buf_size = DBMS_DEFAULT_BUFFER_SIZE,
         ThrottlerPtr throttler_ = {},
         char * existing_memory = nullptr,
-        size_t alignment = 0);
+        size_t alignment = 0,
+        bool use_adaptive_buffer_size_ = false,
+        size_t adaptive_buffer_initial_size = DBMS_DEFAULT_INITIAL_ADAPTIVE_BUFFER_SIZE);
 
     ~WriteBufferFromFile() override;
 

src/IO/WriteBufferFromFileDescriptor.cpp

@@ -83,6 +83,13 @@ void WriteBufferFromFileDescriptor::nextImpl()
 
     ProfileEvents::increment(ProfileEvents::DiskWriteElapsedMicroseconds, watch.elapsedMicroseconds());
     ProfileEvents::increment(ProfileEvents::WriteBufferFromFileDescriptorWriteBytes, bytes_written);
+
+    /// Increase buffer size for next data if adaptive buffer size is used and nextImpl was called because of end of buffer.
+    if (!available() && use_adaptive_buffer_size && memory.size() < adaptive_max_buffer_size)
+    {
+        memory.resize(std::min(memory.size() * 2, adaptive_max_buffer_size));
+        BufferBase::set(memory.data(), memory.size(), 0);
+    }
 }
 
 /// NOTE: This class can be used as a very low-level building block, for example
@@ -94,11 +101,15 @@ WriteBufferFromFileDescriptor::WriteBufferFromFileDescriptor(
     char * existing_memory,
     ThrottlerPtr throttler_,
     size_t alignment,
-    std::string file_name_)
+    std::string file_name_,
-    : WriteBufferFromFileBase(buf_size, existing_memory, alignment)
+    bool use_adaptive_buffer_size_,
+    size_t adaptive_buffer_initial_size)
+    : WriteBufferFromFileBase(use_adaptive_buffer_size_ ? adaptive_buffer_initial_size : buf_size, existing_memory, alignment)
     , fd(fd_)
     , throttler(throttler_)
     , file_name(std::move(file_name_))
+    , use_adaptive_buffer_size(use_adaptive_buffer_size_)
+    , adaptive_max_buffer_size(buf_size)
 {
 }
 
@@ -124,6 +135,7 @@ void WriteBufferFromFileDescriptor::finalizeImpl()
         return;
     }
 
+    use_adaptive_buffer_size = false;
     next();
 }
 

src/IO/WriteBufferFromFileDescriptor.h

@@ -18,7 +18,9 @@ public:
         char * existing_memory = nullptr,
         ThrottlerPtr throttler_ = {},
         size_t alignment = 0,
-        std::string file_name_ = "");
+        std::string file_name_ = "",
+        bool use_adaptive_buffer_size_ = false,
+        size_t adaptive_buffer_initial_size = DBMS_DEFAULT_INITIAL_ADAPTIVE_BUFFER_SIZE);
 
     /** Could be used before initialization if needed 'fd' was not passed to constructor.
       * It's not possible to change 'fd' during work.
@@ -56,6 +58,12 @@ protected:
     /// If file has name contains filename, otherwise contains string "(fd=...)"
     std::string file_name;
 
+    /// If true, the size of internal buffer will be exponentially increased up to
+    /// adaptive_buffer_max_size after each nextImpl call. It can be used to avoid
+    /// large buffer allocation when actual size of writen data is small.
+    bool use_adaptive_buffer_size;
+    size_t adaptive_max_buffer_size;
+
     void finalizeImpl() override;
 };
 

src/IO/WriteBufferFromS3.cpp

@@ -364,10 +364,16 @@ void WriteBufferFromS3::allocateBuffer()
 
 void WriteBufferFromS3::allocateFirstBuffer()
 {
+    /// First buffer was already allocated in BufferWithOwnMemory constructor with provided in constructor buffer size.
+    /// It will be reallocated in subsequent nextImpl calls up to the desired buffer size from buffer_allocation_policy.
+    /// But it may happen that buffer size provided in constructor is larger then desired buffer size from buffer_allocation_policy.
+    /// Resize memory in this case to the desired size.
     const auto max_first_buffer = buffer_allocation_policy->getBufferSize();
-    const auto size = std::min(size_t(DBMS_DEFAULT_BUFFER_SIZE), max_first_buffer);
+    if (memory.size() > max_first_buffer)
-    memory = Memory(size);
+    {
-    WriteBuffer::set(memory.data(), memory.size());
+        memory.resize(max_first_buffer);
+        WriteBuffer::set(memory.data(), memory.size());
+    }
 }
 
 void WriteBufferFromS3::setFakeBufferWhenPreFinalized()

src/IO/WriteSettings.h

@@ -25,6 +25,9 @@ struct WriteSettings
     bool s3_allow_parallel_part_upload = true;
     bool azure_allow_parallel_part_upload = true;
 
+    bool use_adaptive_write_buffer = false;
+    size_t adaptive_write_buffer_initial_size = 16 * 1024;
+
     bool operator==(const WriteSettings & other) const = default;
 };
 

src/Storages/MergeTree/MergeTreeDataPartWriterOnDisk.cpp

@@ -85,11 +85,11 @@ MergeTreeDataPartWriterOnDisk::Stream<false>::Stream(
     marks_file_extension{marks_file_extension_},
     plain_file(data_part_storage->writeFile(data_path_ + data_file_extension, max_compress_block_size_, query_write_settings)),
     plain_hashing(*plain_file),
-    compressor(plain_hashing, compression_codec_, max_compress_block_size_),
+    compressor(plain_hashing, compression_codec_, max_compress_block_size_, query_write_settings.use_adaptive_write_buffer, query_write_settings.adaptive_write_buffer_initial_size),
     compressed_hashing(compressor),
     marks_file(data_part_storage->writeFile(marks_path_ + marks_file_extension, 4096, query_write_settings)),
     marks_hashing(*marks_file),
-    marks_compressor(marks_hashing, marks_compression_codec_, marks_compress_block_size_),
+    marks_compressor(marks_hashing, marks_compression_codec_, marks_compress_block_size_, query_write_settings.use_adaptive_write_buffer, query_write_settings.adaptive_write_buffer_initial_size),
     marks_compressed_hashing(marks_compressor),
     compress_marks(MarkType(marks_file_extension).compressed)
 {
@@ -108,7 +108,7 @@ MergeTreeDataPartWriterOnDisk::Stream<true>::Stream(
     data_file_extension{data_file_extension_},
     plain_file(data_part_storage->writeFile(data_path_ + data_file_extension, max_compress_block_size_, query_write_settings)),
     plain_hashing(*plain_file),
-    compressor(plain_hashing, compression_codec_, max_compress_block_size_),
+    compressor(plain_hashing, compression_codec_, max_compress_block_size_, query_write_settings.use_adaptive_write_buffer, query_write_settings.adaptive_write_buffer_initial_size),
     compressed_hashing(compressor),
     compress_marks(false)
 {

src/Storages/MergeTree/MergeTreeDataPartWriterWide.cpp

@@ -177,6 +177,10 @@ void MergeTreeDataPartWriterWide::addStreams(
         if (!max_compress_block_size)
             max_compress_block_size = settings.max_compress_block_size;
 
+        WriteSettings query_write_settings = settings.query_write_settings;
+        query_write_settings.use_adaptive_write_buffer = settings.use_adaptive_write_buffer_for_dynamic_subcolumns && ISerialization::isDynamicSubcolumn(substream_path, substream_path.size());
+        query_write_settings.adaptive_write_buffer_initial_size = settings.adaptive_write_buffer_initial_size;
+
         column_streams[stream_name] = std::make_unique<Stream<false>>(
             stream_name,
             data_part_storage,
@@ -186,7 +190,7 @@ void MergeTreeDataPartWriterWide::addStreams(
             max_compress_block_size,
             marks_compression_codec,
             settings.marks_compress_block_size,
-            settings.query_write_settings);
+            query_write_settings);
 
         full_name_to_stream_name.emplace(full_stream_name, stream_name);
         stream_name_to_full_name.emplace(stream_name, full_stream_name);

src/Storages/MergeTree/MergeTreeIOSettings.cpp

@@ -30,6 +30,8 @@ MergeTreeWriterSettings::MergeTreeWriterSettings(
     , low_cardinality_max_dictionary_size(global_settings.low_cardinality_max_dictionary_size)
     , low_cardinality_use_single_dictionary_for_part(global_settings.low_cardinality_use_single_dictionary_for_part != 0)
     , use_compact_variant_discriminators_serialization(storage_settings->use_compact_variant_discriminators_serialization)
+    , use_adaptive_write_buffer_for_dynamic_subcolumns(storage_settings->use_adaptive_write_buffer_for_dynamic_subcolumns)
+    , adaptive_write_buffer_initial_size(storage_settings->adaptive_write_buffer_initial_size)
 {
 }
 

src/Storages/MergeTree/MergeTreeIOSettings.h

@@ -80,6 +80,8 @@ struct MergeTreeWriterSettings
     size_t low_cardinality_max_dictionary_size;
     bool low_cardinality_use_single_dictionary_for_part;
     bool use_compact_variant_discriminators_serialization;
+    bool use_adaptive_write_buffer_for_dynamic_subcolumns;
+    size_t adaptive_write_buffer_initial_size;
 };
 
 }

src/Storages/MergeTree/MergeTreeSettings.h

@@ -99,6 +99,8 @@ struct Settings;
     M(Bool, add_implicit_sign_column_constraint_for_collapsing_engine, false, "If true, add implicit constraint for sign column for CollapsingMergeTree engine.", 0) \
     M(Milliseconds, sleep_before_commit_local_part_in_replicated_table_ms, 0, "For testing. Do not change it.", 0) \
     M(Bool, optimize_row_order, false, "Allow reshuffling of rows during part inserts and merges to improve the compressibility of the new part", 0) \
+    M(Bool, use_adaptive_write_buffer_for_dynamic_subcolumns, true, "Allow to use adaptive writer buffers during writing dynamic subcolumns to reduce memory usage", 0) \
+    M(UInt64, adaptive_write_buffer_initial_size, 16 * 1024, "Initial size of an adaptive write buffer", 0) \
     \
     /* Part removal settings. */ \
     M(UInt64, simultaneous_parts_removal_limit, 0, "Maximum number of parts to remove during one CleanupThread iteration (0 means unlimited).", 0) \