240 lines
8.8 KiB
C
240 lines
8.8 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) 1996-2014, 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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* src/include/catalog/pg_control.h
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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 "access/xlogdefs.h"
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#include "pgtime.h" /* for pg_time_t */
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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 942
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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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* Changing this struct requires a PG_CONTROL_VERSION bump.
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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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TimeLineID ThisTimeLineID; /* current TLI */
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TimeLineID PrevTimeLineID; /* previous TLI, if this record begins a new
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* timeline (equals ThisTimeLineID otherwise) */
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bool fullPageWrites; /* current full_page_writes */
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uint32 nextXidEpoch; /* higher-order bits of nextXid */
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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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TransactionId oldestXid; /* cluster-wide minimum datfrozenxid */
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Oid oldestXidDB; /* database with minimum datfrozenxid */
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MultiXactId oldestMulti; /* cluster-wide minimum datminmxid */
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Oid oldestMultiDB; /* database with minimum datminmxid */
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pg_time_t time; /* time stamp of checkpoint */
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TransactionId oldestCommitTs; /* oldest Xid with valid commit timestamp */
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TransactionId newestCommitTs; /* newest Xid with valid commit timestamp */
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/*
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* Oldest XID still running. This is only needed to initialize hot standby
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* mode from an online checkpoint, so we only bother calculating this for
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* online checkpoints and only when wal_level is hot_standby. Otherwise
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* it's set to InvalidTransactionId.
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*/
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TransactionId oldestActiveXid;
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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_NOOP 0x20
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#define XLOG_NEXTOID 0x30
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#define XLOG_SWITCH 0x40
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#define XLOG_BACKUP_END 0x50
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#define XLOG_PARAMETER_CHANGE 0x60
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#define XLOG_RESTORE_POINT 0x70
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#define XLOG_FPW_CHANGE 0x80
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#define XLOG_END_OF_RECOVERY 0x90
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#define XLOG_FPI_FOR_HINT 0xA0
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#define XLOG_FPI 0xB0
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/*
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* System status indicator. Note this is stored in pg_control; if you change
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* it, you must bump PG_CONTROL_VERSION
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*/
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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_SHUTDOWNED_IN_RECOVERY,
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DB_SHUTDOWNING,
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DB_IN_CRASH_RECOVERY,
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DB_IN_ARCHIVE_RECOVERY,
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DB_IN_PRODUCTION
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} DBState;
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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.
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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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pg_time_t time; /* time stamp of last pg_control update */
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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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XLogRecPtr unloggedLSN; /* current fake LSN value, for unlogged rels */
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/*
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* These two values determine the minimum point we must recover up to
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* before starting up:
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*
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* minRecoveryPoint is updated to the latest replayed LSN whenever we
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* flush a data change during archive recovery. That guards against
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* starting archive recovery, aborting it, and restarting with an earlier
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* stop location. If we've already flushed data changes from WAL record X
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* to disk, we mustn't start up until we reach X again. Zero when not
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* doing archive recovery.
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*
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* backupStartPoint is the redo pointer of the backup start checkpoint, if
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* we are recovering from an online backup and haven't reached the end of
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* backup yet. It is reset to zero when the end of backup is reached, and
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* we mustn't start up before that. A boolean would suffice otherwise, but
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* we use the redo pointer as a cross-check when we see an end-of-backup
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* record, to make sure the end-of-backup record corresponds the base
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* backup we're recovering from.
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*
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* backupEndPoint is the backup end location, if we are recovering from an
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* online backup which was taken from the standby and haven't reached the
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* end of backup yet. It is initialized to the minimum recovery point in
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* pg_control which was backed up last. It is reset to zero when the end
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* of backup is reached, and we mustn't start up before that.
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*
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* If backupEndRequired is true, we know for sure that we're restoring
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* from a backup, and must see a backup-end record before we can safely
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* start up. If it's false, but backupStartPoint is set, a backup_label
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* file was found at startup but it may have been a leftover from a stray
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* pg_start_backup() call, not accompanied by pg_stop_backup().
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*/
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XLogRecPtr minRecoveryPoint;
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TimeLineID minRecoveryPointTLI;
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XLogRecPtr backupStartPoint;
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XLogRecPtr backupEndPoint;
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bool backupEndRequired;
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/*
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* Parameter settings that determine if the WAL can be used for archival
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* or hot standby.
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*/
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int wal_level;
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bool wal_log_hints;
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int MaxConnections;
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int max_worker_processes;
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int max_prepared_xacts;
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int max_locks_per_xact;
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bool track_commit_timestamp;
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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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uint32 toast_max_chunk_size; /* chunk size in TOAST tables */
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uint32 loblksize; /* chunk size in pg_largeobject */
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/* flag indicating internal format of timestamp, interval, time */
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bool enableIntTimes; /* int64 storage enabled? */
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/* flags indicating pass-by-value status of various types */
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bool float4ByVal; /* float4 pass-by-value? */
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bool float8ByVal; /* float8, int8, etc pass-by-value? */
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/* Are data pages protected by checksums? Zero if no checksum version */
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uint32 data_checksum_version;
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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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