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58 lines
1.7 KiB
C++
58 lines
1.7 KiB
C++
#pragma once
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#include <string>
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#include <memory>
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#include <Core/Defines.h>
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namespace DB
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{
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class ReadBuffer;
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class WriteBuffer;
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/** These are "generally recognizable" compression methods for data import/export.
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* Do not mess with more efficient compression methods used by ClickHouse internally
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* (they use non-standard framing, indexes, checksums...)
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*/
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enum class CompressionMethod
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{
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None,
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/// DEFLATE compression with gzip header and CRC32 checksum.
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/// This option corresponds to files produced by gzip(1) or HTTP Content-Encoding: gzip.
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Gzip,
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/// DEFLATE compression with zlib header and Adler32 checksum.
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/// This option corresponds to HTTP Content-Encoding: deflate.
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Zlib,
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Brotli
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};
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/// How the compression method is named in HTTP.
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std::string toContentEncodingName(CompressionMethod method);
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/** Choose compression method from path and hint.
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* if hint is "auto" or empty string, then path is analyzed,
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* otherwise path parameter is ignored and hint is used as compression method name.
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* path is arbitrary string that will be analyzed for file extension (gz, br...) that determines compression.
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*/
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CompressionMethod chooseCompressionMethod(const std::string & path, const std::string & hint);
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std::unique_ptr<ReadBuffer> wrapReadBufferWithCompressionMethod(
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std::unique_ptr<ReadBuffer> nested,
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CompressionMethod method,
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size_t buf_size = DBMS_DEFAULT_BUFFER_SIZE,
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char * existing_memory = nullptr,
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size_t alignment = 0);
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std::unique_ptr<WriteBuffer> wrapWriteBufferWithCompressionMethod(
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std::unique_ptr<WriteBuffer> nested,
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CompressionMethod method,
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int level,
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size_t buf_size = DBMS_DEFAULT_BUFFER_SIZE,
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char * existing_memory = nullptr,
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size_t alignment = 0);
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}
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