diff --git a/dbms/programs/server/config.xml b/dbms/programs/server/config.xml
index c1479eaa528..557d1327631 100644
--- a/dbms/programs/server/config.xml
+++ b/dbms/programs/server/config.xml
@@ -25,8 +25,8 @@
     <logger>
         <!-- Possible levels: https://github.com/pocoproject/poco/blob/develop/Foundation/include/Poco/Logger.h#L105 -->
         <level>trace</level>
-        <log>/var/log/clickhouse-server/clickhouse-server.log</log>
-        <errorlog>/var/log/clickhouse-server/clickhouse-server.err.log</errorlog>
+        <log>/home/jokserfn/var/log/clickhouse-server/clickhouse-server.log</log>
+        <errorlog>/home/jokserfn/var/log/clickhouse-server/clickhouse-server.err.log</errorlog>
         <size>1000M</size>
         <count>10</count>
         <!-- <console>1</console> --> <!-- Default behavior is autodetection (log to console if not daemon mode and is tty) -->
@@ -127,13 +127,13 @@
 
 
     <!-- Path to data directory, with trailing slash. -->
-    <path>/var/lib/clickhouse/</path>
+    <path>/home/jokserfn/var/lib/clickhouse/</path>
 
     <!-- Path to temporary data for processing hard queries. -->
-    <tmp_path>/var/lib/clickhouse/tmp/</tmp_path>
+    <tmp_path>/home/jokserfn/var/lib/clickhouse/tmp/</tmp_path>
 
     <!-- Directory with user provided files that are accessible by 'file' table function. -->
-    <user_files_path>/var/lib/clickhouse/user_files/</user_files_path>
+    <user_files_path>/home/jokserfn/var/lib/clickhouse/user_files/</user_files_path>
 
     <!-- Path to configuration file with users, access rights, profiles of settings, quotas. -->
     <users_config>users.xml</users_config>
@@ -327,44 +327,44 @@
     -->
 
     <!-- Query log. Used only for queries with setting log_queries = 1. -->
-    <query_log>
-        <!-- What table to insert data. If table is not exist, it will be created.
+<!--    <query_log>
+        &lt;!&ndash; What table to insert data. If table is not exist, it will be created.
              When query log structure is changed after system update,
               then old table will be renamed and new table will be created automatically.
-        -->
+        &ndash;&gt;
         <database>system</database>
         <table>query_log</table>
-        <!--
+        &lt;!&ndash;
             PARTITION BY expr https://clickhouse.yandex/docs/en/table_engines/custom_partitioning_key/
             Example:
                 event_date
                 toMonday(event_date)
                 toYYYYMM(event_date)
                 toStartOfHour(event_time)
-        -->
+        &ndash;&gt;
         <partition_by>toYYYYMM(event_date)</partition_by>
-        <!-- Interval of flushing data. -->
+        &lt;!&ndash; Interval of flushing data. &ndash;&gt;
         <flush_interval_milliseconds>7500</flush_interval_milliseconds>
-    </query_log>
+    </query_log>-->
 
     <!-- Trace log. Stores stack traces collected by query profilers.
          See query_profiler_real_time_period_ns and query_profiler_cpu_time_period_ns settings. -->
-    <trace_log>
+<!--    <trace_log>
         <database>system</database>
         <table>trace_log</table>
 
         <partition_by>toYYYYMM(event_date)</partition_by>
         <flush_interval_milliseconds>7500</flush_interval_milliseconds>
-    </trace_log>
+    </trace_log>-->
 
     <!-- Query thread log. Has information about all threads participated in query execution.
          Used only for queries with setting log_query_threads = 1. -->
-    <query_thread_log>
+<!--    <query_thread_log>
         <database>system</database>
         <table>query_thread_log</table>
         <partition_by>toYYYYMM(event_date)</partition_by>
         <flush_interval_milliseconds>7500</flush_interval_milliseconds>
-    </query_thread_log>
+    </query_thread_log>-->
 
     <!-- Uncomment if use part log.
          Part log contains information about all actions with parts in MergeTree tables (creation, deletion, merges, downloads).
@@ -489,7 +489,7 @@
     <!-- Directory in <clickhouse-path> containing schema files for various input formats.
          The directory will be created if it doesn't exist.
       -->
-    <format_schema_path>/var/lib/clickhouse/format_schemas/</format_schema_path>
+    <format_schema_path>/home/jokserfn/var/lib/clickhouse/format_schemas/</format_schema_path>
 
 
     <!-- Uncomment to use query masking rules.
diff --git a/dbms/src/Disks/DiskLocal.cpp b/dbms/src/Disks/DiskLocal.cpp
index aed2f71f344..421583a4258 100644
--- a/dbms/src/Disks/DiskLocal.cpp
+++ b/dbms/src/Disks/DiskLocal.cpp
@@ -200,7 +200,7 @@ void DiskLocal::copyFile(const String & from_path, const String & to_path)
     Poco::File(disk_path + from_path).copyTo(disk_path + to_path);
 }
 
-std::unique_ptr<ReadBuffer> DiskLocal::readFile(const String & path, size_t buf_size) const
+std::unique_ptr<SeekableReadBuffer> DiskLocal::readFile(const String & path, size_t buf_size) const
 {
     return std::make_unique<ReadBufferFromFile>(disk_path + path, buf_size);
 }
diff --git a/dbms/src/Disks/DiskLocal.h b/dbms/src/Disks/DiskLocal.h
index 85838d44298..1a9a2e8f6cd 100644
--- a/dbms/src/Disks/DiskLocal.h
+++ b/dbms/src/Disks/DiskLocal.h
@@ -66,7 +66,7 @@ public:
 
     void copyFile(const String & from_path, const String & to_path) override;
 
-    std::unique_ptr<ReadBuffer> readFile(const String & path, size_t buf_size = DBMS_DEFAULT_BUFFER_SIZE) const override;
+    std::unique_ptr<SeekableReadBuffer> readFile(const String & path, size_t buf_size = DBMS_DEFAULT_BUFFER_SIZE) const override;
 
     std::unique_ptr<WriteBuffer> writeFile(const String & path, size_t buf_size = DBMS_DEFAULT_BUFFER_SIZE, WriteMode mode = WriteMode::Rewrite) override;
 
diff --git a/dbms/src/Disks/DiskMemory.cpp b/dbms/src/Disks/DiskMemory.cpp
index 46a73719b5f..521fb796bc3 100644
--- a/dbms/src/Disks/DiskMemory.cpp
+++ b/dbms/src/Disks/DiskMemory.cpp
@@ -4,6 +4,7 @@
 #include <IO/ReadBufferFromString.h>
 #include <IO/WriteBufferFromString.h>
 #include <Interpreters/Context.h>
+#include <IO/SeekableReadBuffer.h>
 
 
 namespace DB
@@ -218,7 +219,7 @@ void DiskMemory::copyFile(const String & /*from_path*/, const String & /*to_path
     throw Exception("Method copyFile is not implemented for memory disks", ErrorCodes::NOT_IMPLEMENTED);
 }
 
-std::unique_ptr<ReadBuffer> DiskMemory::readFile(const String & path, size_t /*buf_size*/) const
+std::unique_ptr<SeekableReadBuffer> DiskMemory::readFile(const String & path, size_t /*buf_size*/) const
 {
     std::lock_guard lock(mutex);
 
diff --git a/dbms/src/Disks/DiskMemory.h b/dbms/src/Disks/DiskMemory.h
index 4ef5b230b1a..f0bed3dfdf9 100644
--- a/dbms/src/Disks/DiskMemory.h
+++ b/dbms/src/Disks/DiskMemory.h
@@ -60,7 +60,8 @@ public:
 
     void copyFile(const String & from_path, const String & to_path) override;
 
-    std::unique_ptr<ReadBuffer> readFile(const String & path, size_t buf_size = DBMS_DEFAULT_BUFFER_SIZE) const override;
+    std::unique_ptr<SeekableReadBuffer> readFile(
+        const String & path, size_t buf_size = DBMS_DEFAULT_BUFFER_SIZE) const override;
 
     std::unique_ptr<WriteBuffer> writeFile(
         const String & path,
diff --git a/dbms/src/Disks/DiskS3.cpp b/dbms/src/Disks/DiskS3.cpp
index 9f20cee15fb..94caf2d018e 100644
--- a/dbms/src/Disks/DiskS3.cpp
+++ b/dbms/src/Disks/DiskS3.cpp
@@ -189,6 +189,7 @@ bool DiskS3::isDirectory(const String & path) const
 
 size_t DiskS3::getFileSize(const String & path) const
 {
+    // TODO: Consider storing actual file size in meta file.
     Aws::S3::Model::GetObjectRequest request;
     request.SetBucket(bucket);
     request.SetKey(getS3Path(path));
@@ -264,13 +265,14 @@ void DiskS3::copyFile(const String & from_path, const String & to_path)
     writeKeyToFile(s3_to_path, metadata_path + to_path);
 }
 
-std::unique_ptr<ReadBuffer> DiskS3::readFile(const String & path, size_t buf_size) const
+std::unique_ptr<SeekableReadBuffer> DiskS3::readFile(const String & path, size_t buf_size) const
 {
     return std::make_unique<ReadBufferFromS3>(client, bucket, getS3Path(path), buf_size);
 }
 
 std::unique_ptr<WriteBuffer> DiskS3::writeFile(const String & path, size_t buf_size, WriteMode mode)
 {
+    // TODO: Optimize append mode. Consider storing several S3 references in one meta file.
     if (!exists(path) || mode == WriteMode::Rewrite)
     {
         String new_s3_path = s3_root_path + getRandomName();
diff --git a/dbms/src/Disks/DiskS3.h b/dbms/src/Disks/DiskS3.h
index c7341fa2183..42c782e6ed2 100644
--- a/dbms/src/Disks/DiskS3.h
+++ b/dbms/src/Disks/DiskS3.h
@@ -7,6 +7,7 @@
 
 #    include <aws/s3/S3Client.h>
 #    include <Poco/DirectoryIterator.h>
+#    include <IO/SeekableReadBuffer.h>
 
 
 namespace DB
@@ -61,7 +62,7 @@ public:
 
     void copyFile(const String & from_path, const String & to_path) override;
 
-    std::unique_ptr<ReadBuffer> readFile(const String & path, size_t buf_size) const override;
+    std::unique_ptr<SeekableReadBuffer> readFile(const String & path, size_t buf_size) const override;
 
     std::unique_ptr<WriteBuffer> writeFile(const String & path, size_t buf_size, WriteMode mode) override;
 
diff --git a/dbms/src/Disks/IDisk.h b/dbms/src/Disks/IDisk.h
index 6ac2745225a..2b189a31d37 100644
--- a/dbms/src/Disks/IDisk.h
+++ b/dbms/src/Disks/IDisk.h
@@ -26,6 +26,7 @@ class IReservation;
 using ReservationPtr = std::unique_ptr<IReservation>;
 
 class ReadBuffer;
+class SeekableReadBuffer;
 class WriteBuffer;
 
 /**
@@ -121,8 +122,8 @@ public:
     /// Copy the file from `from_path` to `to_path`.
     virtual void copyFile(const String & from_path, const String & to_path) = 0;
 
-    /// Open the file for read and return ReadBuffer object.
-    virtual std::unique_ptr<ReadBuffer> readFile(const String & path, size_t buf_size = DBMS_DEFAULT_BUFFER_SIZE) const = 0;
+    /// Open the file for read and return SeekableReadBuffer object.
+    virtual std::unique_ptr<SeekableReadBuffer> readFile(const String & path, size_t buf_size = DBMS_DEFAULT_BUFFER_SIZE) const = 0;
 
     /// Open the file for write and return WriteBuffer object.
     virtual std::unique_ptr<WriteBuffer> writeFile(const String & path, size_t buf_size = DBMS_DEFAULT_BUFFER_SIZE, WriteMode mode = WriteMode::Rewrite) = 0;
diff --git a/dbms/src/IO/ReadBufferFromFileBase.cpp b/dbms/src/IO/ReadBufferFromFileBase.cpp
index e1f9694c85d..feaba0abdd3 100644
--- a/dbms/src/IO/ReadBufferFromFileBase.cpp
+++ b/dbms/src/IO/ReadBufferFromFileBase.cpp
@@ -3,13 +3,12 @@
 namespace DB
 {
 
-ReadBufferFromFileBase::ReadBufferFromFileBase()
-    : BufferWithOwnMemory<ReadBuffer>(0)
+ReadBufferFromFileBase::ReadBufferFromFileBase() : BufferWithOwnMemory<SeekableReadBuffer>(0)
 {
 }
 
 ReadBufferFromFileBase::ReadBufferFromFileBase(size_t buf_size, char * existing_memory, size_t alignment)
-    : BufferWithOwnMemory<ReadBuffer>(buf_size, existing_memory, alignment)
+    : BufferWithOwnMemory<SeekableReadBuffer>(buf_size, existing_memory, alignment)
 {
 }
 
@@ -17,9 +16,4 @@ ReadBufferFromFileBase::~ReadBufferFromFileBase()
 {
 }
 
-off_t ReadBufferFromFileBase::seek(off_t off, int whence)
-{
-    return doSeek(off, whence);
-}
-
 }
diff --git a/dbms/src/IO/ReadBufferFromFileBase.h b/dbms/src/IO/ReadBufferFromFileBase.h
index cf1dff9a574..d9e26d80405 100644
--- a/dbms/src/IO/ReadBufferFromFileBase.h
+++ b/dbms/src/IO/ReadBufferFromFileBase.h
@@ -7,18 +7,18 @@
 #include <IO/ReadBuffer.h>
 #include <IO/BufferWithOwnMemory.h>
 #include <port/clock.h>
+#include "SeekableReadBuffer.h"
 
 namespace DB
 {
 
-class ReadBufferFromFileBase : public BufferWithOwnMemory<ReadBuffer>
+class ReadBufferFromFileBase : public BufferWithOwnMemory<SeekableReadBuffer>
 {
 public:
     ReadBufferFromFileBase();
     ReadBufferFromFileBase(size_t buf_size, char * existing_memory, size_t alignment);
     ReadBufferFromFileBase(ReadBufferFromFileBase &&) = default;
     ~ReadBufferFromFileBase() override;
-    off_t seek(off_t off, int whence = SEEK_SET);
     virtual off_t getPositionInFile() = 0;
     virtual std::string getFileName() const = 0;
     virtual int getFD() const = 0;
@@ -44,8 +44,6 @@ protected:
     ProfileCallback profile_callback;
     clockid_t clock_type{};
 
-    /// Children implementation should be able to seek backwards
-    virtual off_t doSeek(off_t off, int whence) = 0;
 };
 
 }
diff --git a/dbms/src/IO/ReadBufferFromMemory.h b/dbms/src/IO/ReadBufferFromMemory.h
index bcf8d17a1cc..ce8791e4873 100644
--- a/dbms/src/IO/ReadBufferFromMemory.h
+++ b/dbms/src/IO/ReadBufferFromMemory.h
@@ -1,6 +1,7 @@
 #pragma once
 
 #include <IO/ReadBuffer.h>
+#include "SeekableReadBuffer.h"
 
 
 namespace DB
@@ -10,17 +11,20 @@ namespace DB
   * In comparison with just ReadBuffer, it only adds convenient constructors, that do const_cast.
   * In fact, ReadBuffer will not modify data in buffer, but it requires non-const pointer.
   */
-class ReadBufferFromMemory : public ReadBuffer
+class ReadBufferFromMemory : public SeekableReadBuffer
 {
 public:
     ReadBufferFromMemory(const char * buf, size_t size)
-        : ReadBuffer(const_cast<char *>(buf), size, 0) {}
+        : SeekableReadBuffer(const_cast<char *>(buf), size, 0) {}
 
     ReadBufferFromMemory(const unsigned char * buf, size_t size)
-        : ReadBuffer(const_cast<char *>(reinterpret_cast<const char *>(buf)), size, 0) {}
+        : SeekableReadBuffer(const_cast<char *>(reinterpret_cast<const char *>(buf)), size, 0) {}
 
     ReadBufferFromMemory(const signed char * buf, size_t size)
-        : ReadBuffer(const_cast<char *>(reinterpret_cast<const char *>(buf)), size, 0) {}
+        : SeekableReadBuffer(const_cast<char *>(reinterpret_cast<const char *>(buf)), size, 0) {}
+
+protected:
+    off_t doSeek(off_t, int) override { return 0; }
 };
 
 }
diff --git a/dbms/src/IO/ReadBufferFromS3.cpp b/dbms/src/IO/ReadBufferFromS3.cpp
index c29e19ec7ca..9fc7434e8d1 100644
--- a/dbms/src/IO/ReadBufferFromS3.cpp
+++ b/dbms/src/IO/ReadBufferFromS3.cpp
@@ -9,6 +9,8 @@
 #include <aws/s3/model/GetObjectRequest.h>
 #include <aws/s3/S3Client.h>
 
+#include <utility>
+
 namespace DB
 {
 
@@ -18,28 +20,28 @@ namespace ErrorCodes
 }
 
 
-ReadBufferFromS3::ReadBufferFromS3(const std::shared_ptr<Aws::S3::S3Client> & client_ptr,
-        const String & bucket,
-        const String & key,
-        size_t buffer_size_): ReadBuffer(nullptr, 0)
+ReadBufferFromS3::ReadBufferFromS3(
+    std::shared_ptr<Aws::S3::S3Client> client_ptr_,
+    const String & bucket_,
+    const String & key_,
+    size_t buffer_size_
+)
+    : SeekableReadBuffer(nullptr, 0)
+    , client_ptr(std::move(client_ptr_))
+    , bucket(bucket_)
+    , key(key_)
+    , buffer_size(buffer_size_)
 {
-    Aws::S3::Model::GetObjectRequest req;
-    req.SetBucket(bucket);
-    req.SetKey(key);
-
-    Aws::S3::Model::GetObjectOutcome outcome = client_ptr->GetObject(req);
-
-    if (outcome.IsSuccess())
-    {
-        read_result = outcome.GetResultWithOwnership();
-        impl = std::make_unique<ReadBufferFromIStream>(read_result.GetBody(), buffer_size_);
-    }
-    else
-        throw Exception(outcome.GetError().GetMessage(), ErrorCodes::S3_ERROR);
 }
 
 bool ReadBufferFromS3::nextImpl()
 {
+    if (!initialized)
+    {
+        impl = initialize();
+        initialized = true;
+    }
+
     if (!impl->next())
         return false;
     internal_buffer = impl->buffer();
@@ -47,6 +49,31 @@ bool ReadBufferFromS3::nextImpl()
     return true;
 }
 
+off_t ReadBufferFromS3::doSeek(off_t offset_, int) {
+    if (!initialized && offset_)
+        offset = offset_;
+
+    return offset;
+}
+
+std::unique_ptr<ReadBuffer> ReadBufferFromS3::initialize() {
+    Aws::S3::Model::GetObjectRequest req;
+    req.SetBucket(bucket);
+    req.SetKey(key);
+    if (offset != 0)
+        req.SetRange(std::to_string(offset) + "-");
+
+    Aws::S3::Model::GetObjectOutcome outcome = client_ptr->GetObject(req);
+
+    if (outcome.IsSuccess())
+    {
+        read_result = outcome.GetResultWithOwnership();
+        return std::make_unique<ReadBufferFromIStream>(read_result.GetBody(), buffer_size);
+    }
+    else
+        throw Exception(outcome.GetError().GetMessage(), ErrorCodes::S3_ERROR);
+}
+
 }
 
 #endif
diff --git a/dbms/src/IO/ReadBufferFromS3.h b/dbms/src/IO/ReadBufferFromS3.h
index b1065a789f2..fc81efb3b91 100644
--- a/dbms/src/IO/ReadBufferFromS3.h
+++ b/dbms/src/IO/ReadBufferFromS3.h
@@ -9,6 +9,7 @@
 #include <IO/HTTPCommon.h>
 #include <IO/ReadBuffer.h>
 #include <aws/s3/model/GetObjectResult.h>
+#include "SeekableReadBuffer.h"
 
 namespace Aws::S3
 {
@@ -17,24 +18,36 @@ namespace Aws::S3
 
 namespace DB
 {
-/** Perform S3 HTTP GET request and provide response to read.
-  */
-class ReadBufferFromS3 : public ReadBuffer
+/**
+ * Perform S3 HTTP GET request and provide response to read.
+ */
+class ReadBufferFromS3 : public SeekableReadBuffer
 {
 private:
-    Logger * log = &Logger::get("ReadBufferFromS3");
+    std::shared_ptr<Aws::S3::S3Client> client_ptr;
+    String bucket;
+    String key;
+    size_t buffer_size;
+    bool initialized = false;
+    off_t offset = 0;
     Aws::S3::Model::GetObjectResult read_result;
-
-protected:
     std::unique_ptr<ReadBuffer> impl;
 
+    Logger * log = &Logger::get("ReadBufferFromS3");
+
+protected:
+    off_t doSeek(off_t off, int whence) override;
+
 public:
-    explicit ReadBufferFromS3(const std::shared_ptr<Aws::S3::S3Client> & client_ptr,
-        const String & bucket,
-        const String & key,
+    explicit ReadBufferFromS3(std::shared_ptr<Aws::S3::S3Client> client_ptr_,
+        const String & bucket_,
+        const String & key_,
         size_t buffer_size_ = DBMS_DEFAULT_BUFFER_SIZE);
 
     bool nextImpl() override;
+
+private:
+    std::unique_ptr<ReadBuffer> initialize();
 };
 
 }
diff --git a/dbms/src/IO/SeekableReadBuffer.h b/dbms/src/IO/SeekableReadBuffer.h
new file mode 100644
index 00000000000..0ecbf2f9c8b
--- /dev/null
+++ b/dbms/src/IO/SeekableReadBuffer.h
@@ -0,0 +1,29 @@
+#pragma once
+
+#include <string>
+#include <ctime>
+#include <functional>
+#include <fcntl.h>
+#include <IO/ReadBuffer.h>
+#include <IO/BufferWithOwnMemory.h>
+#include <port/clock.h>
+
+namespace DB {
+
+class SeekableReadBuffer : public ReadBuffer {
+public:
+    SeekableReadBuffer(Position ptr, size_t size)
+        : ReadBuffer(ptr, size) {}
+    SeekableReadBuffer(Position ptr, size_t size, size_t offset)
+        : ReadBuffer(ptr, size, offset) {}
+
+    off_t seek(off_t off, int whence = SEEK_SET) {
+        return doSeek(off, whence);
+    };
+
+protected:
+    /// Children implementation should be able to seek backwards
+    virtual off_t doSeek(off_t off, int whence) = 0;
+};
+
+}
diff --git a/dbms/src/Storages/StorageLog.cpp b/dbms/src/Storages/StorageLog.cpp
index 44c3af28267..d411f155422 100644
--- a/dbms/src/Storages/StorageLog.cpp
+++ b/dbms/src/Storages/StorageLog.cpp
@@ -5,8 +5,6 @@
 #include <Common/StringUtils/StringUtils.h>
 #include <Common/typeid_cast.h>
 
-#include <IO/ReadBufferFromFile.h>
-#include <IO/WriteBufferFromFile.h>
 #include <Compression/CompressedReadBuffer.h>
 #include <Compression/CompressedWriteBuffer.h>
 #include <IO/ReadHelpers.h>
@@ -83,14 +81,14 @@ private:
     struct Stream
     {
         Stream(const DiskPtr & disk, const String & data_path, size_t offset, size_t max_read_buffer_size_)
-            : plain(fullPath(disk, data_path), std::min(max_read_buffer_size_, disk->getFileSize(data_path))),
-            compressed(plain)
+            : plain(disk->readFile(data_path, std::min(max_read_buffer_size_, disk->getFileSize(data_path)))),
+            compressed(*plain)
         {
             if (offset)
-                plain.seek(offset);
+                plain->seek(offset);
         }
 
-        ReadBufferFromFile plain;
+        std::unique_ptr<SeekableReadBuffer> plain;
         CompressedReadBuffer compressed;
     };
 
@@ -111,7 +109,7 @@ public:
     explicit LogBlockOutputStream(StorageLog & storage_)
         : storage(storage_),
         lock(storage.rwlock),
-        marks_stream(fullPath(storage.disk, storage.marks_file_path), 4096, O_APPEND | O_CREAT | O_WRONLY)
+        marks_stream(storage.disk->writeFile(storage.marks_file_path, 4096, WriteMode::Append))
     {
     }
 
@@ -139,13 +137,13 @@ private:
     struct Stream
     {
         Stream(const DiskPtr & disk, const String & data_path, CompressionCodecPtr codec, size_t max_compress_block_size) :
-            plain(fullPath(disk, data_path), max_compress_block_size, O_APPEND | O_CREAT | O_WRONLY),
-            compressed(plain, std::move(codec), max_compress_block_size),
+            plain(disk->writeFile(data_path, max_compress_block_size, WriteMode::Append)),
+            compressed(*plain, std::move(codec), max_compress_block_size),
             plain_offset(disk->getFileSize(data_path))
         {
         }
 
-        WriteBufferFromFile plain;
+        std::unique_ptr<WriteBuffer> plain;
         CompressedWriteBuffer compressed;
 
         size_t plain_offset;    /// How many bytes were in the file at the time the LogBlockOutputStream was created.
@@ -153,7 +151,7 @@ private:
         void finalize()
         {
             compressed.next();
-            plain.next();
+            plain->next();
         }
     };
 
@@ -165,7 +163,7 @@ private:
 
     using WrittenStreams = std::set<String>;
 
-    WriteBufferFromFile marks_stream; /// Declared below `lock` to make the file open when rwlock is captured.
+    std::unique_ptr<WriteBuffer> marks_stream; /// Declared below `lock` to make the file open when rwlock is captured.
 
     using SerializeState = IDataType::SerializeBinaryBulkStatePtr;
     using SerializeStates = std::map<String, SerializeState>;
@@ -302,7 +300,7 @@ void LogBlockOutputStream::writeSuffix()
     }
 
     /// Finish write.
-    marks_stream.next();
+    marks_stream->next();
 
     for (auto & name_stream : streams)
         name_stream.second.finalize();
@@ -372,7 +370,7 @@ void LogBlockOutputStream::writeData(const String & name, const IDataType & type
 
         Mark mark;
         mark.rows = (file.marks.empty() ? 0 : file.marks.back().rows) + column.size();
-        mark.offset = stream_it->second.plain_offset + stream_it->second.plain.count();
+        mark.offset = stream_it->second.plain_offset + stream_it->second.plain->count();
 
         out_marks.emplace_back(file.column_index, mark);
     }, settings.path);
@@ -402,8 +400,8 @@ void LogBlockOutputStream::writeMarks(MarksForColumns && marks)
 
     for (const auto & mark : marks)
     {
-        writeIntBinary(mark.second.rows, marks_stream);
-        writeIntBinary(mark.second.offset, marks_stream);
+        writeIntBinary(mark.second.rows, *marks_stream);
+        writeIntBinary(mark.second.offset, *marks_stream);
 
         size_t column_index = mark.first;
         storage.files[storage.column_names_by_idx[column_index]].marks.push_back(mark.second);