Server IP : 85.214.239.14 / Your IP : 18.117.11.13 Web Server : Apache/2.4.62 (Debian) System : Linux h2886529.stratoserver.net 4.9.0 #1 SMP Tue Jan 9 19:45:01 MSK 2024 x86_64 User : www-data ( 33) PHP Version : 7.4.18 Disable Function : pcntl_alarm,pcntl_fork,pcntl_waitpid,pcntl_wait,pcntl_wifexited,pcntl_wifstopped,pcntl_wifsignaled,pcntl_wifcontinued,pcntl_wexitstatus,pcntl_wtermsig,pcntl_wstopsig,pcntl_signal,pcntl_signal_get_handler,pcntl_signal_dispatch,pcntl_get_last_error,pcntl_strerror,pcntl_sigprocmask,pcntl_sigwaitinfo,pcntl_sigtimedwait,pcntl_exec,pcntl_getpriority,pcntl_setpriority,pcntl_async_signals,pcntl_unshare, MySQL : OFF | cURL : OFF | WGET : ON | Perl : ON | Python : ON | Sudo : ON | Pkexec : OFF Directory : /proc/3/cwd/usr/include/postgresql/9.6/server/common/ |
Upload File : |
/* ---------- * pg_lzcompress.h - * * Definitions for the builtin LZ compressor * * src/include/common/pg_lzcompress.h * ---------- */ #ifndef _PG_LZCOMPRESS_H_ #define _PG_LZCOMPRESS_H_ /* ---------- * PGLZ_MAX_OUTPUT - * * Macro to compute the buffer size required by pglz_compress(). * We allow 4 bytes for overrun before detecting compression failure. * ---------- */ #define PGLZ_MAX_OUTPUT(_dlen) ((_dlen) + 4) /* ---------- * PGLZ_Strategy - * * Some values that control the compression algorithm. * * min_input_size Minimum input data size to consider compression. * * max_input_size Maximum input data size to consider compression. * * min_comp_rate Minimum compression rate (0-99%) to require. * Regardless of min_comp_rate, the output must be * smaller than the input, else we don't store * compressed. * * first_success_by Abandon compression if we find no compressible * data within the first this-many bytes. * * match_size_good The initial GOOD match size when starting history * lookup. When looking up the history to find a * match that could be expressed as a tag, the * algorithm does not always walk back entirely. * A good match fast is usually better than the * best possible one very late. For each iteration * in the lookup, this value is lowered so the * longer the lookup takes, the smaller matches * are considered good. * * match_size_drop The percentage by which match_size_good is lowered * after each history check. Allowed values are * 0 (no change until end) to 100 (only check * latest history entry at all). * ---------- */ typedef struct PGLZ_Strategy { int32 min_input_size; int32 max_input_size; int32 min_comp_rate; int32 first_success_by; int32 match_size_good; int32 match_size_drop; } PGLZ_Strategy; /* ---------- * The standard strategies * * PGLZ_strategy_default Recommended default strategy for TOAST. * * PGLZ_strategy_always Try to compress inputs of any length. * Fallback to uncompressed storage only if * output would be larger than input. * ---------- */ extern const PGLZ_Strategy *const PGLZ_strategy_default; extern const PGLZ_Strategy *const PGLZ_strategy_always; /* ---------- * Global function declarations * ---------- */ extern int32 pglz_compress(const char *source, int32 slen, char *dest, const PGLZ_Strategy *strategy); extern int32 pglz_decompress(const char *source, int32 slen, char *dest, int32 rawsize); #endif /* _PG_LZCOMPRESS_H_ */