diff options
Diffstat (limited to 'src/include/access/xlog.h')
| -rw-r--r-- | src/include/access/xlog.h | 30 |
1 files changed, 25 insertions, 5 deletions
diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index d0ff1d99f50..8f9d97adad3 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -6,7 +6,7 @@ * Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * - * $PostgreSQL: pgsql/src/include/access/xlog.h,v 1.48 2004/01/19 19:04:40 tgl Exp $ + * $PostgreSQL: pgsql/src/include/access/xlog.h,v 1.49 2004/02/11 22:55:25 tgl Exp $ */ #ifndef XLOG_H #define XLOG_H @@ -131,15 +131,35 @@ typedef XLogPageHeaderData *XLogPageHeader; #define XLP_ALL_FLAGS 0x0001 /* - * We break each logical log file (xlogid value) into 16Mb segments. - * One possible segment at the end of each log file is wasted, to ensure - * that we don't have problems representing last-byte-position-plus-1. + * We break each logical log file (xlogid value) into segment files of the + * size indicated by XLOG_SEG_SIZE. One possible segment at the end of each + * log file is wasted, to ensure that we don't have problems representing + * last-byte-position-plus-1. */ -#define XLogSegSize ((uint32) (16*1024*1024)) +#define XLogSegSize ((uint32) XLOG_SEG_SIZE) #define XLogSegsPerFile (((uint32) 0xffffffff) / XLogSegSize) #define XLogFileSize (XLogSegsPerFile * XLogSegSize) /* + * The first XLOG record in each segment file is always an XLOG_FILE_HEADER + * record. This record does nothing as far as XLOG replay is concerned, + * but it is useful for verifying that we haven't mixed up XLOG segment files. + * The body of an XLOG_FILE_HEADER record is a struct XLogFileHeaderData. + * Note: the xlogid/segno fields are really redundant with xlp_pageaddr in + * the page header, but we store them anyway as an extra check. + */ +typedef struct XLogFileHeaderData +{ + uint64 xlfhd_sysid; /* system identifier from pg_control */ + uint32 xlfhd_xlogid; /* logical log file # */ + uint32 xlfhd_segno; /* segment number within logical log file */ + uint32 xlfhd_seg_size; /* just as a cross-check */ +} XLogFileHeaderData; + +#define SizeOfXLogFHD MAXALIGN(sizeof(XLogFileHeaderData)) + + +/* * Method table for resource managers. * * RmgrTable[] is indexed by RmgrId values (see rmgr.h). |