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5d5f1a79e6
track shared relations in a separate hashtable, so that operations done from different databases are counted correctly. Add proper support for anti-XID-wraparound vacuuming, even in databases that are never connected to and so have no stats entries. Miscellaneous other bug fixes. Alvaro Herrera, some additional fixes by Tom Lane.
171 lines
6.3 KiB
C
171 lines
6.3 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) 1996-2005, 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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* $PostgreSQL: pgsql/src/include/access/xlog.h,v 1.67 2005/07/29 19:30:08 tgl 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/buf.h"
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#include "utils/pg_crc.h"
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/*
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* The overall layout of an XLOG record is:
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* Fixed-size header (XLogRecord struct)
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* rmgr-specific data
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* BkpBlock
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* backup block data
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* BkpBlock
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* backup block data
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* ...
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*
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* where there can be zero to three backup blocks (as signaled by xl_info flag
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* bits). XLogRecord structs always start on MAXALIGN boundaries in the WAL
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* files, and we round up SizeOfXLogRecord so that the rmgr data is also
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* guaranteed to begin on a MAXALIGN boundary. However, no padding is added
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* to align BkpBlock structs or backup block data.
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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. xl_tot_len counts everything. Neither
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* length field is rounded up to an alignment boundary.
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*/
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typedef struct XLogRecord
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{
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pg_crc32 xl_crc; /* CRC for this record */
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XLogRecPtr xl_prev; /* ptr to previous record in log */
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TransactionId xl_xid; /* xact id */
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uint32 xl_tot_len; /* total len of entire record */
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uint32 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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/* Depending on MAXALIGN, there are either 2 or 6 wasted bytes here */
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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 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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* If we backed up any disk blocks with the XLOG record, we use flag bits in
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* xl_info to signal it. We support backup of up to 3 disk blocks per XLOG
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* record. (Could support 4 if we cared to dedicate all the xl_info bits for
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* this purpose; currently bit 0 of xl_info is unused and available.)
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*/
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#define XLR_BKP_BLOCK_MASK 0x0E /* all info bits used for bkp
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* blocks */
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#define XLR_MAX_BKP_BLOCKS 3
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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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#define XLR_BKP_BLOCK_3 XLR_SET_BKP_BLOCK(2) /* 0x02 */
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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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/* Sync methods */
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#define SYNC_METHOD_FSYNC 0
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#define SYNC_METHOD_FDATASYNC 1
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#define SYNC_METHOD_OPEN 2 /* for O_SYNC and O_DSYNC */
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#define SYNC_METHOD_FSYNC_WRITETHROUGH 3
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extern int sync_method;
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/*
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* The rmgr data to be written by XLogInsert() is defined by a chain of
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* one or more XLogRecData structs. (Multiple structs would be used when
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* parts of the source data aren't physically adjacent in memory, or when
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* multiple associated buffers need to be specified.)
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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 exclusive-locked by the caller, so that it won't change under us.
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* NB: when the buffer is backed up, we DO NOT insert the data pointed to by
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* this XLogRecData struct into the XLOG record, since we assume it's present
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* in the buffer. Therefore, rmgr redo routines MUST pay attention to
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* XLR_BKP_BLOCK_X to know what is actually stored in the XLOG record.
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* The i'th XLR_BKP_BLOCK bit corresponds to the i'th distinct buffer
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* value (ignoring InvalidBuffer) appearing in the rdata chain.
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*
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* When buffer is valid, caller must set buffer_std to indicate whether the
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* page uses standard pd_lower/pd_upper header fields. If this is true, then
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* XLOG is allowed to omit the free space between pd_lower and pd_upper from
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* the backed-up page image. Note that even when buffer_std is false, the
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* page MUST have an LSN field as its first eight bytes!
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*
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* Note: data can be NULL to indicate no rmgr data associated with this chain
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* entry. This can be sensible (ie, not a wasted entry) if buffer is valid.
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* The implication is that the buffer has been changed by the operation being
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* logged, and so may need to be backed up, but the change can be redone using
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* only information already present elsewhere in the XLOG entry.
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*/
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typedef struct XLogRecData
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{
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char *data; /* start of rmgr data to include */
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uint32 len; /* length of rmgr data to include */
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Buffer buffer; /* buffer associated with data, if any */
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bool buffer_std; /* buffer has standard pd_lower/pd_upper */
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struct XLogRecData *next; /* next struct in chain, or NULL */
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} XLogRecData;
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extern TimeLineID ThisTimeLineID; /* current TLI */
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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 bool MyXactMadeTempRelUpdate;
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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 char *XLogArchiveCommand;
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extern char *XLOG_sync_method;
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extern const char XLOG_sync_method_default[];
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#define XLogArchivingActive() (XLogArchiveCommand[0] != '\0')
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#ifdef WAL_DEBUG
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extern bool XLOG_DEBUG;
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#endif
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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_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 BootStrapXLOG(void);
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extern void StartupXLOG(void);
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extern void ShutdownXLOG(int code, Datum arg);
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extern void InitXLOGAccess(void);
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extern void CreateCheckPoint(bool shutdown, bool force);
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extern void XLogPutNextOid(Oid nextOid);
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extern XLogRecPtr GetRedoRecPtr(void);
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extern TransactionId GetRecentNextXid(void);
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#endif /* XLOG_H */
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