Quelle  compression.h

/*-------------------------------------------------------------------------
 *
 * compression.h
 *
 * Shared definitions for compression methods and specifications.
 *
 * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
 *
 * IDENTIFICATION
 *    src/include/common/compression.h
 *-------------------------------------------------------------------------
 */

#ifndef PG_COMPRESSION_H
#define PG_COMPRESSION_H

/*
 * These values are stored in disk, for example in files generated by pg_dump.
 * Create the necessary backwards compatibility layers if their order changes.
 */
typedef enum pg_compress_algorithm
{
 PG_COMPRESSION_NONE,
 PG_COMPRESSION_GZIP,
 PG_COMPRESSION_LZ4,
 PG_COMPRESSION_ZSTD,
} pg_compress_algorithm;

#define PG_COMPRESSION_OPTION_WORKERS  (1 << 0)
#define PG_COMPRESSION_OPTION_LONG_DISTANCE (1 << 1)

typedef struct pg_compress_specification
{
 pg_compress_algorithm algorithm;
 unsigned options;  /* OR of PG_COMPRESSION_OPTION constants */
 int   level;
 int   workers;
 bool  long_distance;
 char    *parse_error; /* NULL if parsing was OK, else message */
} pg_compress_specification;

extern void parse_compress_options(const char *option, char **algorithm,
           char **detail);
extern bool parse_compress_algorithm(char *name, pg_compress_algorithm *algorithm);
extern const char *get_compress_algorithm_name(pg_compress_algorithm algorithm);

extern void parse_compress_specification(pg_compress_algorithm algorithm,
           char *specification,
           pg_compress_specification *result);

extern char *validate_compress_specification(pg_compress_specification *);

#endif