src/include/access/xlog_internal.h

   1 /*
   2  * xlog_internal.h
   3  *
   4  * PostgreSQL write-ahead log internal declarations
   5  *
   6  * NOTE: this file is intended to contain declarations useful for
   7  * manipulating the XLOG files directly, but it is not supposed to be
   8  * needed by rmgr routines (redo support for individual record types).
   9  * So the XLogRecord typedef and associated stuff appear in xlogrecord.h.
  10  *
  11  * Note: This file must be includable in both frontend and backend contexts,
  12  * to allow stand-alone tools like pg_receivewal to deal with WAL files.
  13  *
  14  * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
  15  * Portions Copyright (c) 1994, Regents of the University of California
  16  *
  17  * src/include/access/xlog_internal.h
  18  */
  19 #ifndef XLOG_INTERNAL_H
  20 #define XLOG_INTERNAL_H
  21
  22 #include "access/xlogdefs.h"
  23 #include "access/xlogreader.h"
  24 #include "datatype/timestamp.h"
  25 #include "lib/stringinfo.h"
  26 #include "pgtime.h"
  27 #include "storage/block.h"
  28 #include "storage/relfilenode.h"
  29
  30
  31 /*
  32  * Each page of XLOG file has a header like this:
  33  */
  34 #define XLOG_PAGE_MAGIC 0xD10E  /* can be used as WAL version indicator */
  35
  36 typedef struct XLogPageHeaderData
  37 {
  38         uint16          xlp_magic;              /* magic value for correctness checks */
  39         uint16          xlp_info;               /* flag bits, see below */
  40         TimeLineID      xlp_tli;                /* TimeLineID of first record on page */
  41         XLogRecPtr      xlp_pageaddr;   /* XLOG address of this page */
  42
  43         /*
  44          * When there is not enough space on current page for whole record, we
  45          * continue on the next page.  xlp_rem_len is the number of bytes
  46          * remaining from a previous page; it tracks xl_tot_len in the initial
  47          * header.  Note that the continuation data isn't necessarily aligned.
  48          */
  49         uint32          xlp_rem_len;    /* total len of remaining data for record */
  50 } XLogPageHeaderData;
  51
  52 #define SizeOfXLogShortPHD      MAXALIGN(sizeof(XLogPageHeaderData))
  53
  54 typedef XLogPageHeaderData *XLogPageHeader;
  55
  56 /*
  57  * When the XLP_LONG_HEADER flag is set, we store additional fields in the
  58  * page header.  (This is ordinarily done just in the first page of an
  59  * XLOG file.)  The additional fields serve to identify the file accurately.
  60  */
  61 typedef struct XLogLongPageHeaderData
  62 {
  63         XLogPageHeaderData std;         /* standard header fields */
  64         uint64          xlp_sysid;              /* system identifier from pg_control */
  65         uint32          xlp_seg_size;   /* just as a cross-check */
  66         uint32          xlp_xlog_blcksz;        /* just as a cross-check */
  67 } XLogLongPageHeaderData;
  68
  69 #define SizeOfXLogLongPHD       MAXALIGN(sizeof(XLogLongPageHeaderData))
  70
  71 typedef XLogLongPageHeaderData *XLogLongPageHeader;
  72
  73 /* When record crosses page boundary, set this flag in new page's header */
  74 #define XLP_FIRST_IS_CONTRECORD         0x0001
  75 /* This flag indicates a "long" page header */
  76 #define XLP_LONG_HEADER                         0x0002
  77 /* This flag indicates backup blocks starting in this page are optional */
  78 #define XLP_BKP_REMOVABLE                       0x0004
  79 /* All defined flag bits in xlp_info (used for validity checking of header) */
  80 #define XLP_ALL_FLAGS                           0x0007
  81
  82 #define XLogPageHeaderSize(hdr)         \
  83         (((hdr)->xlp_info & XLP_LONG_HEADER) ? SizeOfXLogLongPHD : SizeOfXLogShortPHD)
  84
  85 /* wal_segment_size can range from 1MB to 1GB */
  86 #define WalSegMinSize 1024 * 1024
  87 #define WalSegMaxSize 1024 * 1024 * 1024
  88 /* default number of min and max wal segments */
  89 #define DEFAULT_MIN_WAL_SEGS 5
  90 #define DEFAULT_MAX_WAL_SEGS 64
  91
  92 /* check that the given size is a valid wal_segment_size */
  93 #define IsPowerOf2(x) (x > 0 && ((x) & ((x)-1)) == 0)
  94 #define IsValidWalSegSize(size) \
  95          (IsPowerOf2(size) && \
  96          ((size) >= WalSegMinSize && (size) <= WalSegMaxSize))
  97
  98 #define XLogSegmentsPerXLogId(wal_segsz_bytes)  \
  99         (UINT64CONST(0x100000000) / (wal_segsz_bytes))
 100
 101 #define XLogSegNoOffsetToRecPtr(segno, offset, wal_segsz_bytes, dest) \
 102                 (dest) = (segno) * (wal_segsz_bytes) + (offset)
 103
 104 #define XLogSegmentOffset(xlogptr, wal_segsz_bytes)     \
 105         ((xlogptr) & ((wal_segsz_bytes) - 1))
 106
 107 /*
 108  * Compute a segment number from an XLogRecPtr.
 109  *
 110  * For XLByteToSeg, do the computation at face value.  For XLByteToPrevSeg,
 111  * a boundary byte is taken to be in the previous segment.  This is suitable
 112  * for deciding which segment to write given a pointer to a record end,
 113  * for example.
 114  */
 115 #define XLByteToSeg(xlrp, logSegNo, wal_segsz_bytes) \
 116         logSegNo = (xlrp) / (wal_segsz_bytes)
 117
 118 #define XLByteToPrevSeg(xlrp, logSegNo, wal_segsz_bytes) \
 119         logSegNo = ((xlrp) - 1) / (wal_segsz_bytes)
 120
 121 /*
 122  * Convert values of GUCs measured in megabytes to equiv. segment count.
 123  * Rounds down.
 124  */
 125 #define XLogMBVarToSegs(mbvar, wal_segsz_bytes) \
 126         ((mbvar) / ((wal_segsz_bytes) / (1024 * 1024)))
 127
 128 /*
 129  * Is an XLogRecPtr within a particular XLOG segment?
 130  *
 131  * For XLByteInSeg, do the computation at face value.  For XLByteInPrevSeg,
 132  * a boundary byte is taken to be in the previous segment.
 133  */
 134 #define XLByteInSeg(xlrp, logSegNo, wal_segsz_bytes) \
 135         (((xlrp) / (wal_segsz_bytes)) == (logSegNo))
 136
 137 #define XLByteInPrevSeg(xlrp, logSegNo, wal_segsz_bytes) \
 138         ((((xlrp) - 1) / (wal_segsz_bytes)) == (logSegNo))
 139
 140 /* Check if an XLogRecPtr value is in a plausible range */
 141 #define XRecOffIsValid(xlrp) \
 142                 ((xlrp) % XLOG_BLCKSZ >= SizeOfXLogShortPHD)
 143
 144 /*
 145  * The XLog directory and control file (relative to $PGDATA)
 146  */
 147 #define XLOGDIR                         "pg_wal"
 148 #define XLOG_CONTROL_FILE       "global/pg_control"
 149
 150 /*
 151  * These macros encapsulate knowledge about the exact layout of XLog file
 152  * names, timeline history file names, and archive-status file names.
 153  */
 154 #define MAXFNAMELEN             64
 155
 156 /* Length of XLog file name */
 157 #define XLOG_FNAME_LEN     24
 158
 159 /*
 160  * Generate a WAL segment file name.  Do not use this macro in a helper
 161  * function allocating the result generated.
 162  */
 163 #define XLogFileName(fname, tli, logSegNo, wal_segsz_bytes)     \
 164         snprintf(fname, MAXFNAMELEN, "%08X%08X%08X", tli,               \
 165                          (uint32) ((logSegNo) / XLogSegmentsPerXLogId(wal_segsz_bytes)), \
 166                          (uint32) ((logSegNo) % XLogSegmentsPerXLogId(wal_segsz_bytes)))
 167
 168 #define XLogFileNameById(fname, tli, log, seg)  \
 169         snprintf(fname, MAXFNAMELEN, "%08X%08X%08X", tli, log, seg)
 170
 171 #define IsXLogFileName(fname) \
 172         (strlen(fname) == XLOG_FNAME_LEN && \
 173          strspn(fname, "0123456789ABCDEF") == XLOG_FNAME_LEN)
 174
 175 /*
 176  * XLOG segment with .partial suffix.  Used by pg_receivewal and at end of
 177  * archive recovery, when we want to archive a WAL segment but it might not
 178  * be complete yet.
 179  */
 180 #define IsPartialXLogFileName(fname)    \
 181         (strlen(fname) == XLOG_FNAME_LEN + strlen(".partial") &&        \
 182          strspn(fname, "0123456789ABCDEF") == XLOG_FNAME_LEN &&         \
 183          strcmp((fname) + XLOG_FNAME_LEN, ".partial") == 0)
 184
 185 #define XLogFromFileName(fname, tli, logSegNo, wal_segsz_bytes) \
 186         do {                                                                                            \
 187                 uint32 log;                                                                             \
 188                 uint32 seg;                                                                             \
 189                 sscanf(fname, "%08X%08X%08X", tli, &log, &seg); \
 190                 *logSegNo = (uint64) log * XLogSegmentsPerXLogId(wal_segsz_bytes) + seg; \
 191         } while (0)
 192
 193 #define XLogFilePath(path, tli, logSegNo, wal_segsz_bytes)      \
 194         snprintf(path, MAXPGPATH, XLOGDIR "/%08X%08X%08X", tli, \
 195                          (uint32) ((logSegNo) / XLogSegmentsPerXLogId(wal_segsz_bytes)), \
 196                          (uint32) ((logSegNo) % XLogSegmentsPerXLogId(wal_segsz_bytes)))
 197
 198 #define TLHistoryFileName(fname, tli)   \
 199         snprintf(fname, MAXFNAMELEN, "%08X.history", tli)
 200
 201 #define IsTLHistoryFileName(fname)      \
 202         (strlen(fname) == 8 + strlen(".history") &&             \
 203          strspn(fname, "0123456789ABCDEF") == 8 &&              \
 204          strcmp((fname) + 8, ".history") == 0)
 205
 206 #define TLHistoryFilePath(path, tli)    \
 207         snprintf(path, MAXPGPATH, XLOGDIR "/%08X.history", tli)
 208
 209 #define StatusFilePath(path, xlog, suffix)      \
 210         snprintf(path, MAXPGPATH, XLOGDIR "/archive_status/%s%s", xlog, suffix)
 211
 212 #define BackupHistoryFileName(fname, tli, logSegNo, startpoint, wal_segsz_bytes) \
 213         snprintf(fname, MAXFNAMELEN, "%08X%08X%08X.%08X.backup", tli, \
 214                          (uint32) ((logSegNo) / XLogSegmentsPerXLogId(wal_segsz_bytes)), \
 215                          (uint32) ((logSegNo) % XLogSegmentsPerXLogId(wal_segsz_bytes)), \
 216                          (uint32) (XLogSegmentOffset(startpoint, wal_segsz_bytes)))
 217
 218 #define IsBackupHistoryFileName(fname) \
 219         (strlen(fname) > XLOG_FNAME_LEN && \
 220          strspn(fname, "0123456789ABCDEF") == XLOG_FNAME_LEN && \
 221          strcmp((fname) + strlen(fname) - strlen(".backup"), ".backup") == 0)
 222
 223 #define BackupHistoryFilePath(path, tli, logSegNo, startpoint, wal_segsz_bytes) \
 224         snprintf(path, MAXPGPATH, XLOGDIR "/%08X%08X%08X.%08X.backup", tli, \
 225                          (uint32) ((logSegNo) / XLogSegmentsPerXLogId(wal_segsz_bytes)), \
 226                          (uint32) ((logSegNo) % XLogSegmentsPerXLogId(wal_segsz_bytes)), \
 227                          (uint32) (XLogSegmentOffset((startpoint), wal_segsz_bytes)))
 228
 229 /*
 230  * Information logged when we detect a change in one of the parameters
 231  * important for Hot Standby.
 232  */
 233 typedef struct xl_parameter_change
 234 {
 235         int                     MaxConnections;
 236         int                     max_worker_processes;
 237         int                     max_wal_senders;
 238         int                     max_prepared_xacts;
 239         int                     max_locks_per_xact;
 240         int                     wal_level;
 241         bool            wal_log_hints;
 242         bool            track_commit_timestamp;
 243 } xl_parameter_change;
 244
 245 /* logs restore point */
 246 typedef struct xl_restore_point
 247 {
 248         TimestampTz rp_time;
 249         char            rp_name[MAXFNAMELEN];
 250 } xl_restore_point;
 251
 252 /* End of recovery mark, when we don't do an END_OF_RECOVERY checkpoint */
 253 typedef struct xl_end_of_recovery
 254 {
 255         TimestampTz end_time;
 256         TimeLineID      ThisTimeLineID; /* new TLI */
 257         TimeLineID      PrevTimeLineID; /* previous TLI we forked off from */
 258 } xl_end_of_recovery;
 259
 260 /*
 261  * The functions in xloginsert.c construct a chain of XLogRecData structs
 262  * to represent the final WAL record.
 263  */
 264 typedef struct XLogRecData
 265 {
 266         struct XLogRecData *next;       /* next struct in chain, or NULL */
 267         char       *data;                       /* start of rmgr data to include */
 268         uint32          len;                    /* length of rmgr data to include */
 269 } XLogRecData;
 270
 271 /*
 272  * Recovery target action.
 273  */
 274 typedef enum
 275 {
 276         RECOVERY_TARGET_ACTION_PAUSE,
 277         RECOVERY_TARGET_ACTION_PROMOTE,
 278         RECOVERY_TARGET_ACTION_SHUTDOWN
 279 }                       RecoveryTargetAction;
 280
 281 /*
 282  * Method table for resource managers.
 283  *
 284  * This struct must be kept in sync with the PG_RMGR definition in
 285  * rmgr.c.
 286  *
 287  * rm_identify must return a name for the record based on xl_info (without
 288  * reference to the rmid). For example, XLOG_BTREE_VACUUM would be named
 289  * "VACUUM". rm_desc can then be called to obtain additional detail for the
 290  * record, if available (e.g. the last block).
 291  *
 292  * rm_mask takes as input a page modified by the resource manager and masks
 293  * out bits that shouldn't be flagged by wal_consistency_checking.
 294  *
 295  * RmgrTable[] is indexed by RmgrId values (see rmgrlist.h).
 296  */
 297 typedef struct RmgrData
 298 {
 299         const char *rm_name;
 300         void            (*rm_redo) (XLogReaderState *record);
 301         void            (*rm_desc) (StringInfo buf, XLogReaderState *record);
 302         const char *(*rm_identify) (uint8 info);
 303         void            (*rm_startup) (void);
 304         void            (*rm_cleanup) (void);
 305         void            (*rm_mask) (char *pagedata, BlockNumber blkno);
 306 } RmgrData;
 307
 308 extern const RmgrData RmgrTable[];
 309
 310 /*
 311  * Exported to support xlog switching from checkpointer
 312  */
 313 extern pg_time_t GetLastSegSwitchData(XLogRecPtr *lastSwitchLSN);
 314 extern XLogRecPtr RequestXLogSwitch(bool mark_unimportant);
 315
 316 extern void GetOldestRestartPoint(XLogRecPtr *oldrecptr, TimeLineID *oldtli);
 317
 318 /*
 319  * Exported for the functions in timeline.c and xlogarchive.c.  Only valid
 320  * in the startup process.
 321  */
 322 extern bool ArchiveRecoveryRequested;
 323 extern bool InArchiveRecovery;
 324 extern bool StandbyMode;
 325 extern char *recoveryRestoreCommand;
 326
 327 #endif                                                  /* XLOG_INTERNAL_H */