From 75a3fa4e68235f956f8761e43adf25be2fc9147c Mon Sep 17 00:00:00 2001 From: Justin Pryzby Date: Sat, 23 Oct 2021 10:41:19 -0500 Subject: [PATCH 2/6] Save bits in xlog FPI record.. 2 bits can support 4 methods (including 'none'), and 3 bits can support 8 See also: https://www.postgresql.org/message-id/20220131222800.GY23027@telsasoft.com --- src/backend/access/transam/xloginsert.c | 29 +++---------------------- src/backend/access/transam/xlogreader.c | 7 +++--- src/bin/pg_waldump/pg_waldump.c | 16 +++++--------- src/include/access/xlogrecord.h | 17 ++++++++++----- 4 files changed, 23 insertions(+), 46 deletions(-) diff --git a/src/backend/access/transam/xloginsert.c b/src/backend/access/transam/xloginsert.c index 847ce0c3fc..5f9d07156a 100644 --- a/src/backend/access/transam/xloginsert.c +++ b/src/backend/access/transam/xloginsert.c @@ -689,33 +689,10 @@ XLogRecordAssemble(RmgrId rmid, uint8 info, bimg.length = compressed_len; /* Set the compression method used for this block */ - switch ((WalCompression) wal_compression) - { - case WAL_COMPRESSION_PGLZ: - bimg.bimg_info |= BKPIMAGE_COMPRESS_PGLZ; - break; - - case WAL_COMPRESSION_LZ4: -#ifdef USE_LZ4 - bimg.bimg_info |= BKPIMAGE_COMPRESS_LZ4; -#else - elog(ERROR, "LZ4 is not supported by this build"); -#endif - break; + Assert(wal_compression < (1 << BKPIMAGE_COMPRESS_BITS)); - case WAL_COMPRESSION_ZSTD: -#ifdef USE_ZSTD - bimg.bimg_info |= BKPIMAGE_COMPRESS_ZSTD; -#else - elog(ERROR, "ZSTD is not supported by this build"); -#endif - break; - - case WAL_COMPRESSION_NONE: - Assert(false); /* cannot happen */ - break; - /* no default case, so that compiler will warn */ - } + bimg.bimg_info |= + wal_compression << BKPIMAGE_COMPRESS_OFFSET_BITS; rdt_datas_last->data = regbuf->compressed_page; rdt_datas_last->len = compressed_len; diff --git a/src/backend/access/transam/xlogreader.c b/src/backend/access/transam/xlogreader.c index d60e4cbaf6..d2d882d0d1 100644 --- a/src/backend/access/transam/xlogreader.c +++ b/src/backend/access/transam/xlogreader.c @@ -1602,14 +1602,15 @@ RestoreBlockImage(XLogReaderState *record, uint8 block_id, char *page) { /* If a backup block image is compressed, decompress it */ bool decomp_success = true; + int compressid = BKPIMAGE_COMPRESSION(bkpb->bimg_info); - if ((bkpb->bimg_info & BKPIMAGE_COMPRESS_PGLZ) != 0) + if (compressid == WAL_COMPRESSION_PGLZ) { if (pglz_decompress(ptr, bkpb->bimg_len, tmp.data, BLCKSZ - bkpb->hole_length, true) < 0) decomp_success = false; } - else if ((bkpb->bimg_info & BKPIMAGE_COMPRESS_LZ4) != 0) + else if (compressid == WAL_COMPRESSION_LZ4) { #ifdef USE_LZ4 if (LZ4_decompress_safe(ptr, tmp.data, @@ -1623,7 +1624,7 @@ RestoreBlockImage(XLogReaderState *record, uint8 block_id, char *page) return false; #endif } - else if ((bkpb->bimg_info & BKPIMAGE_COMPRESS_ZSTD) != 0) + else if (compressid == WAL_COMPRESSION_ZSTD) { #ifdef USE_ZSTD size_t decomp_result = ZSTD_decompress(tmp.data, diff --git a/src/bin/pg_waldump/pg_waldump.c b/src/bin/pg_waldump/pg_waldump.c index c448658ea2..bec3fda2aa 100644 --- a/src/bin/pg_waldump/pg_waldump.c +++ b/src/bin/pg_waldump/pg_waldump.c @@ -18,6 +18,7 @@ #include #include "access/transam.h" +#include "access/xlog.h" #include "access/xlog_internal.h" #include "access/xlogreader.h" #include "access/xlogrecord.h" @@ -559,17 +560,10 @@ XLogDumpDisplayRecord(XLogDumpConfig *config, XLogReaderState *record) if (BKPIMAGE_COMPRESSED(bimg_info)) { - const char *method; - - if ((bimg_info & BKPIMAGE_COMPRESS_PGLZ) != 0) - method = "pglz"; - else if ((bimg_info & BKPIMAGE_COMPRESS_LZ4) != 0) - method = "lz4"; - else if ((bimg_info & BKPIMAGE_COMPRESS_ZSTD) != 0) - method = "zstd"; - else - method = "unknown"; + int compressid = BKPIMAGE_COMPRESSION(bimg_info); + const char *methods[] = {"none", "pglz", "lz4", "zstd"}; + Assert(compressid < lengthof(methods)); printf(" (FPW%s); hole: offset: %u, length: %u, " "compression saved: %u, method: %s", XLogRecBlockImageApply(record, block_id) ? @@ -579,7 +573,7 @@ XLogDumpDisplayRecord(XLogDumpConfig *config, XLogReaderState *record) BLCKSZ - record->blocks[block_id].hole_length - record->blocks[block_id].bimg_len, - method); + methods[compressid]); } else { diff --git a/src/include/access/xlogrecord.h b/src/include/access/xlogrecord.h index 052ac6817a..2080fb707f 100644 --- a/src/include/access/xlogrecord.h +++ b/src/include/access/xlogrecord.h @@ -147,13 +147,18 @@ typedef struct XLogRecordBlockImageHeader #define BKPIMAGE_APPLY 0x02 /* page image should be restored * during replay */ /* compression methods supported */ -#define BKPIMAGE_COMPRESS_PGLZ 0x04 -#define BKPIMAGE_COMPRESS_LZ4 0x08 -#define BKPIMAGE_COMPRESS_ZSTD 0x10 - +#define BKPIMAGE_COMPRESS_METHOD1 0x04 /* bits to encode compression method */ +#define BKPIMAGE_COMPRESS_METHOD2 0x08 /* 0=none, 1=pglz, 2=lz4, 3=zstd */ + +/* How many bits to shift to extract compression */ +#define BKPIMAGE_COMPRESS_OFFSET_BITS 2 +/* How many bits are for compression */ +#define BKPIMAGE_COMPRESS_BITS 2 +/* Extract the compression from the bimg_info */ +#define BKPIMAGE_COMPRESSION(info) ((info >> BKPIMAGE_COMPRESS_OFFSET_BITS) & ((1<