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Diffstat (limited to 'src/include/catalog/pg_control.h')
| -rw-r--r-- | src/include/catalog/pg_control.h | 258 |
1 files changed, 258 insertions, 0 deletions
diff --git a/src/include/catalog/pg_control.h b/src/include/catalog/pg_control.h new file mode 100644 index 0000000..dc95397 --- /dev/null +++ b/src/include/catalog/pg_control.h @@ -0,0 +1,258 @@ +/*------------------------------------------------------------------------- + * + * 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) 1996-2023, 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/transam.h" +#include "access/xlogdefs.h" +#include "pgtime.h" /* for pg_time_t */ +#include "port/pg_crc32c.h" + + +/* Version identifier for this pg_control format */ +#define PG_CONTROL_VERSION 1300 + +/* Nonce key length, see below */ +#define MOCK_AUTH_NONCE_LEN 32 + +/* + * 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 */ + TimeLineID PrevTimeLineID; /* previous TLI, if this record begins a new + * timeline (equals ThisTimeLineID otherwise) */ + bool fullPageWrites; /* current full_page_writes */ + FullTransactionId nextXid; /* next free transaction ID */ + 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 */ + MultiXactId oldestMulti; /* cluster-wide minimum datminmxid */ + Oid oldestMultiDB; /* database with minimum datminmxid */ + pg_time_t time; /* time stamp of checkpoint */ + TransactionId oldestCommitTsXid; /* oldest Xid with valid commit + * timestamp */ + TransactionId newestCommitTsXid; /* newest Xid with valid commit + * timestamp */ + + /* + * 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 replica. 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 +#define XLOG_END_OF_RECOVERY 0x90 +#define XLOG_FPI_FOR_HINT 0xA0 +#define XLOG_FPI 0xB0 +/* 0xC0 is used in Postgres 9.5-11 */ +#define XLOG_OVERWRITE_CONTRECORD 0xD0 + + +/* + * 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. + */ + +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 */ + + CheckPoint checkPointCopy; /* copy of last check point record */ + + XLogRecPtr unloggedLSN; /* current fake LSN value, for unlogged rels */ + + /* + * 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. + */ + XLogRecPtr minRecoveryPoint; + TimeLineID minRecoveryPointTLI; + XLogRecPtr backupStartPoint; + XLogRecPtr backupEndPoint; + bool backupEndRequired; + + /* + * Parameter settings that determine if the WAL can be used for archival + * or hot standby. + */ + int wal_level; + bool wal_log_hints; + int MaxConnections; + int max_worker_processes; + int max_wal_senders; + int max_prepared_xacts; + int max_locks_per_xact; + bool track_commit_timestamp; + + /* + * 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 */ + uint32 loblksize; /* chunk size in pg_largeobject */ + + bool float8ByVal; /* float8, int8, etc pass-by-value? */ + + /* Are data pages protected by checksums? Zero if no checksum version */ + uint32 data_checksum_version; + + /* + * Random nonce, used in authentication requests that need to proceed + * based on values that are cluster-unique, like a SASL exchange that + * failed at an early stage. + */ + char mock_authentication_nonce[MOCK_AUTH_NONCE_LEN]; + + /* CRC of all above ... MUST BE LAST! */ + pg_crc32c crc; +} ControlFileData; + +/* + * Maximum safe value of sizeof(ControlFileData). For reliability's sake, + * it's critical that pg_control updates be atomic writes. That generally + * means the active data can't be more than one disk sector, which is 512 + * bytes on common hardware. Be very careful about raising this limit. + */ +#define PG_CONTROL_MAX_SAFE_SIZE 512 + +/* + * 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_FILE_SIZE 8192 + +/* + * Ensure that the size of the pg_control data structure is sane. + */ +StaticAssertDecl(sizeof(ControlFileData) <= PG_CONTROL_MAX_SAFE_SIZE, + "pg_control is too large for atomic disk writes"); +StaticAssertDecl(sizeof(ControlFileData) <= PG_CONTROL_FILE_SIZE, + "sizeof(ControlFileData) exceeds PG_CONTROL_FILE_SIZE"); + +#endif /* PG_CONTROL_H */ |