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pg_control.h
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1 /*-------------------------------------------------------------------------
2  *
3  * pg_control.h
4  * The system control file "pg_control" is not a heap relation.
5  * However, we define it here so that the format is documented.
6  *
7  *
8  * Portions Copyright (c) 1996-2017, PostgreSQL Global Development Group
9  * Portions Copyright (c) 1994, Regents of the University of California
10  *
11  * src/include/catalog/pg_control.h
12  *
13  *-------------------------------------------------------------------------
14  */
15 #ifndef PG_CONTROL_H
16 #define PG_CONTROL_H
17 
18 #include "access/xlogdefs.h"
19 #include "pgtime.h" /* for pg_time_t */
20 #include "port/pg_crc32c.h"
21 
22 
23 #define MOCK_AUTH_NONCE_LEN 32
24 
25 /* Version identifier for this pg_control format */
26 #define PG_CONTROL_VERSION 1002
27 
28 /*
29  * Body of CheckPoint XLOG records. This is declared here because we keep
30  * a copy of the latest one in pg_control for possible disaster recovery.
31  * Changing this struct requires a PG_CONTROL_VERSION bump.
32  */
33 typedef struct CheckPoint
34 {
35  XLogRecPtr redo; /* next RecPtr available when we began to
36  * create CheckPoint (i.e. REDO start point) */
37  TimeLineID ThisTimeLineID; /* current TLI */
38  TimeLineID PrevTimeLineID; /* previous TLI, if this record begins a new
39  * timeline (equals ThisTimeLineID otherwise) */
40  bool fullPageWrites; /* current full_page_writes */
41  uint32 nextXidEpoch; /* higher-order bits of nextXid */
42  TransactionId nextXid; /* next free XID */
43  Oid nextOid; /* next free OID */
44  MultiXactId nextMulti; /* next free MultiXactId */
45  MultiXactOffset nextMultiOffset; /* next free MultiXact offset */
46  TransactionId oldestXid; /* cluster-wide minimum datfrozenxid */
47  Oid oldestXidDB; /* database with minimum datfrozenxid */
48  MultiXactId oldestMulti; /* cluster-wide minimum datminmxid */
49  Oid oldestMultiDB; /* database with minimum datminmxid */
50  pg_time_t time; /* time stamp of checkpoint */
51  TransactionId oldestCommitTsXid; /* oldest Xid with valid commit
52  * timestamp */
53  TransactionId newestCommitTsXid; /* newest Xid with valid commit
54  * timestamp */
55 
56  /*
57  * Oldest XID still running. This is only needed to initialize hot standby
58  * mode from an online checkpoint, so we only bother calculating this for
59  * online checkpoints and only when wal_level is replica. Otherwise it's
60  * set to InvalidTransactionId.
61  */
63 } CheckPoint;
64 
65 /* XLOG info values for XLOG rmgr */
66 #define XLOG_CHECKPOINT_SHUTDOWN 0x00
67 #define XLOG_CHECKPOINT_ONLINE 0x10
68 #define XLOG_NOOP 0x20
69 #define XLOG_NEXTOID 0x30
70 #define XLOG_SWITCH 0x40
71 #define XLOG_BACKUP_END 0x50
72 #define XLOG_PARAMETER_CHANGE 0x60
73 #define XLOG_RESTORE_POINT 0x70
74 #define XLOG_FPW_CHANGE 0x80
75 #define XLOG_END_OF_RECOVERY 0x90
76 #define XLOG_FPI_FOR_HINT 0xA0
77 #define XLOG_FPI 0xB0
78 
79 
80 /*
81  * System status indicator. Note this is stored in pg_control; if you change
82  * it, you must bump PG_CONTROL_VERSION
83  */
84 typedef enum DBState
85 {
93 } DBState;
94 
95 /*
96  * Contents of pg_control.
97  *
98  * NOTE: try to keep this under 512 bytes so that it will fit on one physical
99  * sector of typical disk drives. This reduces the odds of corruption due to
100  * power failure midway through a write.
101  */
102 
103 typedef struct ControlFileData
104 {
105  /*
106  * Unique system identifier --- to ensure we match up xlog files with the
107  * installation that produced them.
108  */
110 
111  /*
112  * Version identifier information. Keep these fields at the same offset,
113  * especially pg_control_version; they won't be real useful if they move
114  * around. (For historical reasons they must be 8 bytes into the file
115  * rather than immediately at the front.)
116  *
117  * pg_control_version identifies the format of pg_control itself.
118  * catalog_version_no identifies the format of the system catalogs.
119  *
120  * There are additional version identifiers in individual files; for
121  * example, WAL logs contain per-page magic numbers that can serve as
122  * version cues for the WAL log.
123  */
124  uint32 pg_control_version; /* PG_CONTROL_VERSION */
125  uint32 catalog_version_no; /* see catversion.h */
126 
127  /*
128  * System status data
129  */
130  DBState state; /* see enum above */
131  pg_time_t time; /* time stamp of last pg_control update */
132  XLogRecPtr checkPoint; /* last check point record ptr */
133  XLogRecPtr prevCheckPoint; /* previous check point record ptr */
134 
135  CheckPoint checkPointCopy; /* copy of last check point record */
136 
137  XLogRecPtr unloggedLSN; /* current fake LSN value, for unlogged rels */
138 
139  /*
140  * These two values determine the minimum point we must recover up to
141  * before starting up:
142  *
143  * minRecoveryPoint is updated to the latest replayed LSN whenever we
144  * flush a data change during archive recovery. That guards against
145  * starting archive recovery, aborting it, and restarting with an earlier
146  * stop location. If we've already flushed data changes from WAL record X
147  * to disk, we mustn't start up until we reach X again. Zero when not
148  * doing archive recovery.
149  *
150  * backupStartPoint is the redo pointer of the backup start checkpoint, if
151  * we are recovering from an online backup and haven't reached the end of
152  * backup yet. It is reset to zero when the end of backup is reached, and
153  * we mustn't start up before that. A boolean would suffice otherwise, but
154  * we use the redo pointer as a cross-check when we see an end-of-backup
155  * record, to make sure the end-of-backup record corresponds the base
156  * backup we're recovering from.
157  *
158  * backupEndPoint is the backup end location, if we are recovering from an
159  * online backup which was taken from the standby and haven't reached the
160  * end of backup yet. It is initialized to the minimum recovery point in
161  * pg_control which was backed up last. It is reset to zero when the end
162  * of backup is reached, and we mustn't start up before that.
163  *
164  * If backupEndRequired is true, we know for sure that we're restoring
165  * from a backup, and must see a backup-end record before we can safely
166  * start up. If it's false, but backupStartPoint is set, a backup_label
167  * file was found at startup but it may have been a leftover from a stray
168  * pg_start_backup() call, not accompanied by pg_stop_backup().
169  */
175 
176  /*
177  * Parameter settings that determine if the WAL can be used for archival
178  * or hot standby.
179  */
187 
188  /*
189  * This data is used to check for hardware-architecture compatibility of
190  * the database and the backend executable. We need not check endianness
191  * explicitly, since the pg_control version will surely look wrong to a
192  * machine of different endianness, but we do need to worry about MAXALIGN
193  * and floating-point format. (Note: storage layout nominally also
194  * depends on SHORTALIGN and INTALIGN, but in practice these are the same
195  * on all architectures of interest.)
196  *
197  * Testing just one double value is not a very bulletproof test for
198  * floating-point compatibility, but it will catch most cases.
199  */
200  uint32 maxAlign; /* alignment requirement for tuples */
201  double floatFormat; /* constant 1234567.0 */
202 #define FLOATFORMAT_VALUE 1234567.0
203 
204  /*
205  * This data is used to make sure that configuration of this database is
206  * compatible with the backend executable.
207  */
208  uint32 blcksz; /* data block size for this DB */
209  uint32 relseg_size; /* blocks per segment of large relation */
210 
211  uint32 xlog_blcksz; /* block size within WAL files */
212  uint32 xlog_seg_size; /* size of each WAL segment */
213 
214  uint32 nameDataLen; /* catalog name field width */
215  uint32 indexMaxKeys; /* max number of columns in an index */
216 
217  uint32 toast_max_chunk_size; /* chunk size in TOAST tables */
218  uint32 loblksize; /* chunk size in pg_largeobject */
219 
220  /* flags indicating pass-by-value status of various types */
221  bool float4ByVal; /* float4 pass-by-value? */
222  bool float8ByVal; /* float8, int8, etc pass-by-value? */
223 
224  /* Are data pages protected by checksums? Zero if no checksum version */
226 
227  /*
228  * Random nonce, used in authentication requests that need to proceed
229  * based on values that are cluster-unique, like a SASL exchange that
230  * failed at an early stage.
231  */
233 
234  /* CRC of all above ... MUST BE LAST! */
237 
238 /*
239  * Physical size of the pg_control file. Note that this is considerably
240  * bigger than the actually used size (ie, sizeof(ControlFileData)).
241  * The idea is to keep the physical size constant independent of format
242  * changes, so that ReadControlFile will deliver a suitable wrong-version
243  * message instead of a read error if it's looking at an incompatible file.
244  */
245 #define PG_CONTROL_SIZE 8192
246 
247 #endif /* PG_CONTROL_H */
int max_locks_per_xact
Definition: pg_control.h:185
int max_prepared_xacts
Definition: pg_control.h:184
uint32 TimeLineID
Definition: xlogdefs.h:45
int64 pg_time_t
Definition: pgtime.h:23
uint32 MultiXactOffset
Definition: c.h:409
pg_time_t time
Definition: pg_control.h:131
uint32 TransactionId
Definition: c.h:397
TimeLineID minRecoveryPointTLI
Definition: pg_control.h:171
int max_worker_processes
Definition: pg_control.h:183
uint32 pg_crc32c
Definition: pg_crc32c.h:38
TransactionId oldestActiveXid
Definition: pg_control.h:62
uint32 nameDataLen
Definition: pg_control.h:214
MultiXactId oldestMulti
Definition: pg_control.h:48
TimeLineID PrevTimeLineID
Definition: pg_control.h:38
uint32 pg_control_version
Definition: pg_control.h:124
CheckPoint checkPointCopy
Definition: pg_control.h:135
uint32 xlog_blcksz
Definition: pg_control.h:211
TransactionId oldestXid
Definition: pg_control.h:46
unsigned int Oid
Definition: postgres_ext.h:31
TransactionId nextXid
Definition: pg_control.h:42
pg_time_t time
Definition: pg_control.h:50
#define MOCK_AUTH_NONCE_LEN
Definition: pg_control.h:23
bool backupEndRequired
Definition: pg_control.h:174
MultiXactOffset nextMultiOffset
Definition: pg_control.h:45
TransactionId oldestCommitTsXid
Definition: pg_control.h:51
uint32 xlog_seg_size
Definition: pg_control.h:212
uint64 system_identifier
Definition: pg_control.h:109
uint32 nextXidEpoch
Definition: pg_control.h:41
uint32 data_checksum_version
Definition: pg_control.h:225
struct ControlFileData ControlFileData
XLogRecPtr unloggedLSN
Definition: pg_control.h:137
unsigned int uint32
Definition: c.h:268
pg_crc32c crc
Definition: pg_control.h:235
uint32 loblksize
Definition: pg_control.h:218
uint32 indexMaxKeys
Definition: pg_control.h:215
DBState
Definition: pg_control.h:84
TransactionId newestCommitTsXid
Definition: pg_control.h:53
char mock_authentication_nonce[MOCK_AUTH_NONCE_LEN]
Definition: pg_control.h:232
Oid oldestMultiDB
Definition: pg_control.h:49
XLogRecPtr prevCheckPoint
Definition: pg_control.h:133
uint32 toast_max_chunk_size
Definition: pg_control.h:217
Oid nextOid
Definition: pg_control.h:43
XLogRecPtr backupEndPoint
Definition: pg_control.h:173
bool fullPageWrites
Definition: pg_control.h:40
TransactionId MultiXactId
Definition: c.h:407
bool track_commit_timestamp
Definition: pg_control.h:186
uint64 XLogRecPtr
Definition: xlogdefs.h:21
Oid oldestXidDB
Definition: pg_control.h:47
double floatFormat
Definition: pg_control.h:201
MultiXactId nextMulti
Definition: pg_control.h:44
uint32 catalog_version_no
Definition: pg_control.h:125
struct CheckPoint CheckPoint
TimeLineID ThisTimeLineID
Definition: pg_control.h:37
XLogRecPtr backupStartPoint
Definition: pg_control.h:172
uint32 relseg_size
Definition: pg_control.h:209
XLogRecPtr checkPoint
Definition: pg_control.h:132
XLogRecPtr redo
Definition: pg_control.h:35
XLogRecPtr minRecoveryPoint
Definition: pg_control.h:170