src/include/access/xlogutils.h

   1 /*
   2  * xlogutils.h
   3  *
   4  * Utilities for replaying WAL records.
   5  *
   6  * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
   7  * Portions Copyright (c) 1994, Regents of the University of California
   8  *
   9  * src/include/access/xlogutils.h
  10  */
  11 #ifndef XLOG_UTILS_H
  12 #define XLOG_UTILS_H
  13
  14 #include "access/xlogreader.h"
  15 #include "storage/bufmgr.h"
  16
  17 /*
  18  * Prior to 8.4, all activity during recovery was carried out by the startup
  19  * process. This local variable continues to be used in many parts of the
  20  * code to indicate actions taken by RecoveryManagers. Other processes that
  21  * potentially perform work during recovery should check RecoveryInProgress().
  22  * See XLogCtl notes in xlog.c.
  23  */
  24 extern bool InRecovery;
  25
  26 /*
  27  * Like InRecovery, standbyState is only valid in the startup process.
  28  * In all other processes it will have the value STANDBY_DISABLED (so
  29  * InHotStandby will read as false).
  30  *
  31  * In DISABLED state, we're performing crash recovery or hot standby was
  32  * disabled in postgresql.conf.
  33  *
  34  * In INITIALIZED state, we've run InitRecoveryTransactionEnvironment, but
  35  * we haven't yet processed a RUNNING_XACTS or shutdown-checkpoint WAL record
  36  * to initialize our primary-transaction tracking system.
  37  *
  38  * When the transaction tracking is initialized, we enter the SNAPSHOT_PENDING
  39  * state. The tracked information might still be incomplete, so we can't allow
  40  * connections yet, but redo functions must update the in-memory state when
  41  * appropriate.
  42  *
  43  * In SNAPSHOT_READY mode, we have full knowledge of transactions that are
  44  * (or were) running on the primary at the current WAL location. Snapshots
  45  * can be taken, and read-only queries can be run.
  46  */
  47 typedef enum
  48 {
  49         STANDBY_DISABLED,
  50         STANDBY_INITIALIZED,
  51         STANDBY_SNAPSHOT_PENDING,
  52         STANDBY_SNAPSHOT_READY
  53 } HotStandbyState;
  54
  55 extern HotStandbyState standbyState;
  56
  57 #define InHotStandby (standbyState >= STANDBY_SNAPSHOT_PENDING)
  58
  59
  60 extern bool XLogHaveInvalidPages(void);
  61 extern void XLogCheckInvalidPages(void);
  62
  63 extern void XLogDropRelation(RelFileNode rnode, ForkNumber forknum);
  64 extern void XLogDropDatabase(Oid dbid);
  65 extern void XLogTruncateRelation(RelFileNode rnode, ForkNumber forkNum,
  66                                                                  BlockNumber nblocks);
  67
  68 /* Result codes for XLogReadBufferForRedo[Extended] */
  69 typedef enum
  70 {
  71         BLK_NEEDS_REDO,                         /* changes from WAL record need to be applied */
  72         BLK_DONE,                                       /* block is already up-to-date */
  73         BLK_RESTORED,                           /* block was restored from a full-page image */
  74         BLK_NOTFOUND                            /* block was not found (and hence does not
  75                                                                  * need to be replayed) */
  76 } XLogRedoAction;
  77
  78 extern XLogRedoAction XLogReadBufferForRedo(XLogReaderState *record,
  79                                                                                         uint8 buffer_id, Buffer *buf);
  80 extern Buffer XLogInitBufferForRedo(XLogReaderState *record, uint8 block_id);
  81 extern XLogRedoAction XLogReadBufferForRedoExtended(XLogReaderState *record,
  82                                                                                                         uint8 buffer_id,
  83                                                                                                         ReadBufferMode mode, bool get_cleanup_lock,
  84                                                                                                         Buffer *buf);
  85
  86 extern Buffer XLogReadBufferExtended(RelFileNode rnode, ForkNumber forknum,
  87                                                                          BlockNumber blkno, ReadBufferMode mode);
  88
  89 extern Relation CreateFakeRelcacheEntry(RelFileNode rnode);
  90 extern void FreeFakeRelcacheEntry(Relation fakerel);
  91
  92 extern int      read_local_xlog_page(XLogReaderState *state,
  93                                                                  XLogRecPtr targetPagePtr, int reqLen,
  94                                                                  XLogRecPtr targetRecPtr, char *cur_page);
  95 extern void wal_segment_open(XLogReaderState *state,
  96                                                          XLogSegNo nextSegNo,
  97                                                          TimeLineID *tli_p);
  98 extern void wal_segment_close(XLogReaderState *state);
  99
 100 extern void XLogReadDetermineTimeline(XLogReaderState *state,
 101                                                                           XLogRecPtr wantPage, uint32 wantLength);
 102
 103 extern void WALReadRaiseError(WALReadError *errinfo);
 104
 105 #endif