227 lines
7.2 KiB
C
227 lines
7.2 KiB
C
/*
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* xlog.h
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*
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* PostgreSQL transaction log manager
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*
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* Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* $Id: xlog.h,v 1.32 2002/08/04 06:26:38 thomas Exp $
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*/
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#ifndef XLOG_H
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#define XLOG_H
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#include "access/rmgr.h"
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#include "access/transam.h"
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#include "access/xlogdefs.h"
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#include "storage/bufmgr.h"
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#include "utils/pg_crc.h"
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/*
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* Header for each record in XLOG
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*
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* NOTE: xl_len counts only the rmgr data, not the XLogRecord header,
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* and also not any backup blocks appended to the record (which are signaled
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* by xl_info flag bits). The total space needed for an XLOG record is
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* really:
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*
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* SizeOfXLogRecord + xl_len + n_backup_blocks * (sizeof(BkpBlock) + BLCKSZ)
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*
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* rounded up to a MAXALIGN boundary (so that all xlog records start on
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* MAXALIGN boundaries).
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*/
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typedef struct XLogRecord
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{
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crc64 xl_crc; /* CRC for this record */
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XLogRecPtr xl_prev; /* ptr to previous record in log */
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XLogRecPtr xl_xact_prev; /* ptr to previous record of this xact */
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TransactionId xl_xid; /* xact id */
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uint16 xl_len; /* total len of rmgr data */
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uint8 xl_info; /* flag bits, see below */
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RmgrId xl_rmid; /* resource manager for this record */
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/* ACTUAL LOG DATA FOLLOWS AT END OF STRUCT */
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} XLogRecord;
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#define SizeOfXLogRecord MAXALIGN(sizeof(XLogRecord))
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#define MAXLOGRECSZ 65535 /* the most that'll fit in xl_len */
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#define XLogRecGetData(record) ((char*) (record) + SizeOfXLogRecord)
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/*
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* XLOG uses only low 4 bits of xl_info. High 4 bits may be used by rmgr.
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*/
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#define XLR_INFO_MASK 0x0F
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/*
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* We support backup of up to 2 disk blocks per XLOG record (could support
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* more if we cared to dedicate more xl_info bits for this purpose; currently
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* do not need more than 2 anyway). If we backed up any disk blocks then we
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* use flag bits in xl_info to signal it.
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*/
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#define XLR_BKP_BLOCK_MASK 0x0C /* all info bits used for bkp
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* blocks */
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#define XLR_MAX_BKP_BLOCKS 2
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#define XLR_SET_BKP_BLOCK(iblk) (0x08 >> (iblk))
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#define XLR_BKP_BLOCK_1 XLR_SET_BKP_BLOCK(0) /* 0x08 */
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#define XLR_BKP_BLOCK_2 XLR_SET_BKP_BLOCK(1) /* 0x04 */
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/*
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* Sometimes we log records which are out of transaction control.
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* Rmgr may "or" XLOG_NO_TRAN into info passed to XLogInsert to indicate this.
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*/
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#define XLOG_NO_TRAN XLR_INFO_MASK
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/*
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* Header info for a backup block appended to an XLOG record.
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*
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* Note that the backup block has its own CRC, and is not covered by
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* the CRC of the XLOG record proper. Also note that we don't attempt
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* to align either the BkpBlock struct or the block's data.
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*/
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typedef struct BkpBlock
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{
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crc64 crc;
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RelFileNode node;
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BlockNumber block;
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} BkpBlock;
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/*
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* When there is not enough space on current page for whole record, we
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* continue on the next page with continuation record. (However, the
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* XLogRecord header will never be split across pages; if there's less than
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* SizeOfXLogRecord space left at the end of a page, we just waste it.)
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*
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* Note that xl_rem_len includes backup-block data, unlike xl_len in the
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* initial header.
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*/
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typedef struct XLogContRecord
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{
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uint32 xl_rem_len; /* total len of remaining data for record */
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/* ACTUAL LOG DATA FOLLOWS AT END OF STRUCT */
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} XLogContRecord;
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#define SizeOfXLogContRecord MAXALIGN(sizeof(XLogContRecord))
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/*
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* Each page of XLOG file has a header like this:
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*/
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#define XLOG_PAGE_MAGIC 0xD059 /* can be used as WAL version indicator */
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typedef struct XLogPageHeaderData
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{
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uint16 xlp_magic; /* magic value for correctness checks */
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uint16 xlp_info; /* flag bits, see below */
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StartUpID xlp_sui; /* StartUpID of first record on page */
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XLogRecPtr xlp_pageaddr; /* XLOG address of this page */
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} XLogPageHeaderData;
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#define SizeOfXLogPHD MAXALIGN(sizeof(XLogPageHeaderData))
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typedef XLogPageHeaderData *XLogPageHeader;
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/* When record crosses page boundary, set this flag in new page's header */
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#define XLP_FIRST_IS_CONTRECORD 0x0001
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/* All defined flag bits in xlp_info (used for validity checking of header) */
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#define XLP_ALL_FLAGS 0x0001
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/*
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* We break each logical log file (xlogid value) into 16Mb segments.
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* One possible segment at the end of each log file is wasted, to ensure
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* that we don't have problems representing last-byte-position-plus-1.
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*/
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#define XLogSegSize ((uint32) (16*1024*1024))
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#define XLogSegsPerFile (((uint32) 0xffffffff) / XLogSegSize)
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#define XLogFileSize (XLogSegsPerFile * XLogSegSize)
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/*
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* Method table for resource managers.
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*
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* RmgrTable[] is indexed by RmgrId values (see rmgr.h).
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*/
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typedef struct RmgrData
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{
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char *rm_name;
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void (*rm_redo) (XLogRecPtr lsn, XLogRecord *rptr);
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void (*rm_undo) (XLogRecPtr lsn, XLogRecord *rptr);
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void (*rm_desc) (char *buf, uint8 xl_info, char *rec);
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} RmgrData;
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extern RmgrData RmgrTable[];
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/*--------------------
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* List of these structs is used to pass data to XLogInsert().
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*
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* If buffer is valid then XLOG will check if buffer must be backed up
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* (ie, whether this is first change of that page since last checkpoint).
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* If so, the whole page contents are attached to the XLOG record, and XLOG
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* sets XLR_BKP_BLOCK_X bit in xl_info. Note that the buffer must be pinned
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* and locked while this is going on, so that it won't change under us.
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* NB: when this happens, we do not bother to insert the associated data into
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* the XLOG record, since we assume it's present in the buffer. Therefore,
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* rmgr redo routines MUST pay attention to XLR_BKP_BLOCK_X to know what
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* is actually stored in the XLOG record.
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*--------------------
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*/
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typedef struct XLogRecData
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{
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Buffer buffer; /* buffer associated with this data */
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char *data;
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uint32 len;
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struct XLogRecData *next;
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} XLogRecData;
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/* XLOG directory name */
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extern char XLogDir[];
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extern StartUpID ThisStartUpID; /* current SUI */
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extern bool InRecovery;
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extern XLogRecPtr MyLastRecPtr;
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extern bool MyXactMadeXLogEntry;
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extern XLogRecPtr ProcLastRecEnd;
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/* these variables are GUC parameters related to XLOG */
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extern int CheckPointSegments;
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extern int XLOGbuffers;
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extern int XLOGfiles;
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extern int XLOG_DEBUG;
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extern char *XLOG_sync_method;
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extern const char XLOG_sync_method_default[];
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extern void SetXLogDir(char *path);
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extern XLogRecPtr XLogInsert(RmgrId rmid, uint8 info, XLogRecData *rdata);
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extern void XLogFlush(XLogRecPtr RecPtr);
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extern void xlog_redo(XLogRecPtr lsn, XLogRecord *record);
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extern void xlog_undo(XLogRecPtr lsn, XLogRecord *record);
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extern void xlog_desc(char *buf, uint8 xl_info, char *rec);
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extern void UpdateControlFile(void);
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extern int XLOGShmemSize(void);
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extern void XLOGShmemInit(void);
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extern void XLOGPathInit(void);
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extern void BootStrapXLOG(void);
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extern void StartupXLOG(void);
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extern void ShutdownXLOG(void);
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extern void CreateCheckPoint(bool shutdown);
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extern void SetThisStartUpID(void);
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extern void XLogPutNextOid(Oid nextOid);
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extern void SetSavedRedoRecPtr(void);
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extern void GetSavedRedoRecPtr(void);
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extern XLogRecPtr GetRedoRecPtr(void);
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/* in storage/ipc/sinval.c, but don't want to declare in sinval.h because
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* we'd have to include xlog.h into that ...
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*/
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extern XLogRecPtr GetUndoRecPtr(void);
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extern const char *assign_xlog_sync_method(const char *method,
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bool doit, bool interactive);
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#endif /* XLOG_H */
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