ClickHouse/dbms/IO/CompressionMethod.h
Ivan 97f2a2213e
Move all folders inside /dbms one level up (#9974)
* Move some code outside dbms/src folder
* Fix paths
2020-04-02 02:51:21 +03:00

58 lines
1.7 KiB
C++

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