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Merge pull request #49733 from ClickHouse/nickitat-patch-11

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Do not allocate own buffer in CachedOnDiskReadBufferFromFile when `use_external_buffer == true`
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Kseniia Sumarokova 2023-05-12 00:05:25 +02:00 committed by GitHub
commit f5b959624d
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1 changed files with 3 additions and 5 deletions
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8
src/Disks/IO/CachedOnDiskReadBufferFromFile.cpp
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@ -50,7 +50,7 @@ CachedOnDiskReadBufferFromFile::CachedOnDiskReadBufferFromFile(
bool use_external_buffer_,
std::optional<size_t> read_until_position_,
std::shared_ptr<FilesystemCacheLog> cache_log_)
: ReadBufferFromFileBase(settings_.remote_fs_buffer_size, nullptr, 0, file_size_)
: ReadBufferFromFileBase(use_external_buffer_ ? 0 : settings_.remote_fs_buffer_size, nullptr, 0, file_size_)
#ifndef NDEBUG
, log(&Poco::Logger::get("CachedOnDiskReadBufferFromFile(" + source_file_path_ + ")"))
#else
@ -151,10 +151,8 @@ CachedOnDiskReadBufferFromFile::getCacheReadBuffer(const FileSegment & file_segm
/// Do not allow to use asynchronous version of LocalFSReadMethod.
local_read_settings.local_fs_method = LocalFSReadMethod::pread;
// The buffer will unnecessarily allocate a Memory of size local_fs_buffer_size, which will then
// most likely be unused because we're swap()ping our own internal_buffer into
// implementation_buffer before each read. But we can't just set local_fs_buffer_size = 0 here
// because some buffer implementations actually use that memory (e.g. for prefetching).
if (use_external_buffer)
local_read_settings.local_fs_buffer_size = 0;
auto buf = createReadBufferFromFileBase(path, local_read_settings);