compression.h

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/*-------------------------------------------------------------------------
 *
 * compression.h
 *
 * Shared definitions for compression methods and specifications.
 *
 * Portions Copyright (c) 1996-2026, 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