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/*------------------------------------------------------------------------- * * pg_control.h * The system control file "pg_control" is not a heap relation. * However, we define it here so that the format is documented. * * * Portions Copyright (c) 1996-2012, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * * src/include/catalog/pg_control.h * *------------------------------------------------------------------------- */ #ifndef PG_CONTROL_H #define PG_CONTROL_H #include "access/xlogdefs.h" #include "pgtime.h" /* for pg_time_t */ #include "utils/pg_crc.h" /* Version identifier for this pg_control format */ #define PG_CONTROL_VERSION 922 /* * Body of CheckPoint XLOG records. This is declared here because we keep * a copy of the latest one in pg_control for possible disaster recovery. * Changing this struct requires a PG_CONTROL_VERSION bump. */ typedef struct CheckPoint { XLogRecPtr redo; /* next RecPtr available when we began to * create CheckPoint (i.e. REDO start point) */ TimeLineID ThisTimeLineID; /* current TLI */ bool fullPageWrites; /* current full_page_writes */ uint32 nextXidEpoch; /* higher-order bits of nextXid */ TransactionId nextXid; /* next free XID */ Oid nextOid; /* next free OID */ MultiXactId nextMulti; /* next free MultiXactId */ MultiXactOffset nextMultiOffset; /* next free MultiXact offset */ TransactionId oldestXid; /* cluster-wide minimum datfrozenxid */ Oid oldestXidDB; /* database with minimum datfrozenxid */ pg_time_t time; /* time stamp of checkpoint */ /* * Oldest XID still running. This is only needed to initialize hot standby * mode from an online checkpoint, so we only bother calculating this for * online checkpoints and only when wal_level is hot_standby. Otherwise * it's set to InvalidTransactionId. */ TransactionId oldestActiveXid; } CheckPoint; /* XLOG info values for XLOG rmgr */ #define XLOG_CHECKPOINT_SHUTDOWN 0x00 #define XLOG_CHECKPOINT_ONLINE 0x10 #define XLOG_NOOP 0x20 #define XLOG_NEXTOID 0x30 #define XLOG_SWITCH 0x40 #define XLOG_BACKUP_END 0x50 #define XLOG_PARAMETER_CHANGE 0x60 #define XLOG_RESTORE_POINT 0x70 #define XLOG_FPW_CHANGE 0x80 /* * System status indicator. Note this is stored in pg_control; if you change * it, you must bump PG_CONTROL_VERSION */ typedef enum DBState { DB_STARTUP = 0, DB_SHUTDOWNED, DB_SHUTDOWNED_IN_RECOVERY, DB_SHUTDOWNING, DB_IN_CRASH_RECOVERY, DB_IN_ARCHIVE_RECOVERY, DB_IN_PRODUCTION } DBState; /* * Contents of pg_control. * * NOTE: try to keep this under 512 bytes so that it will fit on one physical * sector of typical disk drives. This reduces the odds of corruption due to * power failure midway through a write. */ typedef struct ControlFileData { /* * Unique system identifier --- to ensure we match up xlog files with the * installation that produced them. */ uint64 system_identifier; /* * Version identifier information. Keep these fields at the same offset, * especially pg_control_version; they won't be real useful if they move * around. (For historical reasons they must be 8 bytes into the file * rather than immediately at the front.) * * pg_control_version identifies the format of pg_control itself. * catalog_version_no identifies the format of the system catalogs. * * There are additional version identifiers in individual files; for * example, WAL logs contain per-page magic numbers that can serve as * version cues for the WAL log. */ uint32 pg_control_version; /* PG_CONTROL_VERSION */ uint32 catalog_version_no; /* see catversion.h */ /* * System status data */ DBState state; /* see enum above */ pg_time_t time; /* time stamp of last pg_control update */ XLogRecPtr checkPoint; /* last check point record ptr */ XLogRecPtr prevCheckPoint; /* previous check point record ptr */ CheckPoint checkPointCopy; /* copy of last check point record */ /* * These two values determine the minimum point we must recover up to * before starting up: * * minRecoveryPoint is updated to the latest replayed LSN whenever we * flush a data change during archive recovery. That guards against * starting archive recovery, aborting it, and restarting with an earlier * stop location. If we've already flushed data changes from WAL record X * to disk, we mustn't start up until we reach X again. Zero when not * doing archive recovery. * * backupStartPoint is the redo pointer of the backup start checkpoint, if * we are recovering from an online backup and haven't reached the end of * backup yet. It is reset to zero when the end of backup is reached, and * we mustn't start up before that. A boolean would suffice otherwise, but * we use the redo pointer as a cross-check when we see an end-of-backup * record, to make sure the end-of-backup record corresponds the base * backup we're recovering from. * * backupEndPoint is the backup end location, if we are recovering from an * online backup which was taken from the standby and haven't reached the * end of backup yet. It is initialized to the minimum recovery point in * pg_control which was backed up last. It is reset to zero when the end * of backup is reached, and we mustn't start up before that. * * If backupEndRequired is true, we know for sure that we're restoring * from a backup, and must see a backup-end record before we can safely * start up. If it's false, but backupStartPoint is set, a backup_label * file was found at startup but it may have been a leftover from a stray * pg_start_backup() call, not accompanied by pg_stop_backup(). */ XLogRecPtr minRecoveryPoint; XLogRecPtr backupStartPoint; XLogRecPtr backupEndPoint; bool backupEndRequired; /* * Parameter settings that determine if the WAL can be used for archival * or hot standby. */ int wal_level; int MaxConnections; int max_prepared_xacts; int max_locks_per_xact; /* * This data is used to check for hardware-architecture compatibility of * the database and the backend executable. We need not check endianness * explicitly, since the pg_control version will surely look wrong to a * machine of different endianness, but we do need to worry about MAXALIGN * and floating-point format. (Note: storage layout nominally also * depends on SHORTALIGN and INTALIGN, but in practice these are the same * on all architectures of interest.) * * Testing just one double value is not a very bulletproof test for * floating-point compatibility, but it will catch most cases. */ uint32 maxAlign; /* alignment requirement for tuples */ double floatFormat; /* constant 1234567.0 */ #define FLOATFORMAT_VALUE 1234567.0 /* * This data is used to make sure that configuration of this database is * compatible with the backend executable. */ uint32 blcksz; /* data block size for this DB */ uint32 relseg_size; /* blocks per segment of large relation */ uint32 xlog_blcksz; /* block size within WAL files */ uint32 xlog_seg_size; /* size of each WAL segment */ uint32 nameDataLen; /* catalog name field width */ uint32 indexMaxKeys; /* max number of columns in an index */ uint32 toast_max_chunk_size; /* chunk size in TOAST tables */ /* flag indicating internal format of timestamp, interval, time */ bool enableIntTimes; /* int64 storage enabled? */ /* flags indicating pass-by-value status of various types */ bool float4ByVal; /* float4 pass-by-value? */ bool float8ByVal; /* float8, int8, etc pass-by-value? */ /* CRC of all above ... MUST BE LAST! */ pg_crc32 crc; } ControlFileData; /* * Physical size of the pg_control file. Note that this is considerably * bigger than the actually used size (ie, sizeof(ControlFileData)). * The idea is to keep the physical size constant independent of format * changes, so that ReadControlFile will deliver a suitable wrong-version * message instead of a read error if it's looking at an incompatible file. */ #define PG_CONTROL_SIZE 8192 #endif /* PG_CONTROL_H */