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e6140d9052
instead a dedicated symbol. This probably makes no functional difference for likely values of BLCKSZ, but it makes the intent clearer. Simon Riggs, minor editorialization by Tom Lane.
160 lines
5.3 KiB
C
160 lines
5.3 KiB
C
/*-------------------------------------------------------------------------
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*
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* pg_control.h
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* The system control file "pg_control" is not a heap relation.
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* However, we define it here so that the format is documented.
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*
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*
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* Portions Copyright (c) 1996-2006, 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/catalog/pg_control.h,v 1.29 2006/04/04 22:39:59 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef PG_CONTROL_H
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#define PG_CONTROL_H
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#include <time.h>
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#include "access/xlogdefs.h"
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#include "utils/pg_crc.h"
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/* Version identifier for this pg_control format */
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#define PG_CONTROL_VERSION 820
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/*
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* Body of CheckPoint XLOG records. This is declared here because we keep
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* a copy of the latest one in pg_control for possible disaster recovery.
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*/
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typedef struct CheckPoint
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{
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XLogRecPtr redo; /* next RecPtr available when we began to
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* create CheckPoint (i.e. REDO start point) */
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XLogRecPtr undo; /* first record of oldest in-progress
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* transaction when we started (i.e. UNDO end
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* point) */
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TimeLineID ThisTimeLineID; /* current TLI */
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TransactionId nextXid; /* next free XID */
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Oid nextOid; /* next free OID */
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MultiXactId nextMulti; /* next free MultiXactId */
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MultiXactOffset nextMultiOffset; /* next free MultiXact offset */
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time_t time; /* time stamp of checkpoint */
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} CheckPoint;
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/* XLOG info values for XLOG rmgr */
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#define XLOG_CHECKPOINT_SHUTDOWN 0x00
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#define XLOG_CHECKPOINT_ONLINE 0x10
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#define XLOG_NEXTOID 0x30
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/* System status indicator */
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typedef enum DBState
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{
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DB_STARTUP = 0,
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DB_SHUTDOWNED,
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DB_SHUTDOWNING,
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DB_IN_RECOVERY,
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DB_IN_PRODUCTION
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} DBState;
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#define LOCALE_NAME_BUFLEN 128
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/*
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* Contents of pg_control.
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*
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* NOTE: try to keep this under 512 bytes so that it will fit on one physical
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* sector of typical disk drives. This reduces the odds of corruption due to
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* power failure midway through a write. Currently it fits comfortably,
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* but we could probably reduce LOCALE_NAME_BUFLEN if things get tight.
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*/
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typedef struct ControlFileData
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{
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/*
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* Unique system identifier --- to ensure we match up xlog files with the
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* installation that produced them.
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*/
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uint64 system_identifier;
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/*
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* Version identifier information. Keep these fields at the same offset,
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* especially pg_control_version; they won't be real useful if they move
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* around. (For historical reasons they must be 8 bytes into the file
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* rather than immediately at the front.)
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*
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* pg_control_version identifies the format of pg_control itself.
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* catalog_version_no identifies the format of the system catalogs.
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*
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* There are additional version identifiers in individual files; for
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* example, WAL logs contain per-page magic numbers that can serve as
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* version cues for the WAL log.
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*/
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uint32 pg_control_version; /* PG_CONTROL_VERSION */
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uint32 catalog_version_no; /* see catversion.h */
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/*
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* System status data
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*/
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DBState state; /* see enum above */
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time_t time; /* time stamp of last pg_control update */
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uint32 logId; /* current log file id */
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uint32 logSeg; /* current log file segment, + 1 */
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XLogRecPtr checkPoint; /* last check point record ptr */
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XLogRecPtr prevCheckPoint; /* previous check point record ptr */
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CheckPoint checkPointCopy; /* copy of last check point record */
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/*
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* This data is used to check for hardware-architecture compatibility of
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* the database and the backend executable. We need not check endianness
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* explicitly, since the pg_control version will surely look wrong to a
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* machine of different endianness, but we do need to worry about MAXALIGN
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* and floating-point format. (Note: storage layout nominally also
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* depends on SHORTALIGN and INTALIGN, but in practice these are the same
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* on all architectures of interest.)
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*
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* Testing just one double value is not a very bulletproof test for
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* floating-point compatibility, but it will catch most cases.
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*/
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uint32 maxAlign; /* alignment requirement for tuples */
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double floatFormat; /* constant 1234567.0 */
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#define FLOATFORMAT_VALUE 1234567.0
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/*
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* This data is used to make sure that configuration of this database is
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* compatible with the backend executable.
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*/
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uint32 blcksz; /* data block size for this DB */
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uint32 relseg_size; /* blocks per segment of large relation */
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uint32 xlog_blcksz; /* block size within WAL files */
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uint32 xlog_seg_size; /* size of each WAL segment */
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uint32 nameDataLen; /* catalog name field width */
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uint32 indexMaxKeys; /* max number of columns in an index */
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/* flag indicating internal format of timestamp, interval, time */
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uint32 enableIntTimes; /* int64 storage enabled? */
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/* active locales */
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uint32 localeBuflen;
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char lc_collate[LOCALE_NAME_BUFLEN];
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char lc_ctype[LOCALE_NAME_BUFLEN];
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/* CRC of all above ... MUST BE LAST! */
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pg_crc32 crc;
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} ControlFileData;
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/*
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* Physical size of the pg_control file. Note that this is considerably
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* bigger than the actually used size (ie, sizeof(ControlFileData)).
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* The idea is to keep the physical size constant independent of format
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* changes, so that ReadControlFile will deliver a suitable wrong-version
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* message instead of a read error if it's looking at an incompatible file.
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*/
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#define PG_CONTROL_SIZE 8192
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#endif /* PG_CONTROL_H */
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