@ -7,7 +7,7 @@
* Portions Copyright ( c ) 1996 - 2003 , PostgreSQL Global Development Group
* Portions Copyright ( c ) 1994 , Regents of the University of California
*
* $ PostgreSQL : pgsql / src / backend / access / transam / xlog . c , v 1.153 2004 / 08 / 01 17 : 45 : 4 2 tgl Exp $
* $ PostgreSQL : pgsql / src / backend / access / transam / xlog . c , v 1.154 2004 / 08 / 03 20 : 32 : 3 2 tgl Exp $
*
* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
*/
@ -5048,3 +5048,233 @@ issue_xlog_fsync(void)
break ;
}
}
/*
* pg_start_backup : set up for taking an on - line backup dump
*
* Essentially what this does is to create a backup label file in $ PGDATA ,
* where it will be archived as part of the backup dump . The label file
* contains the user - supplied label string ( typically this would be used
* to tell where the backup dump will be stored ) and the starting time and
* starting WAL offset for the dump .
*/
Datum
pg_start_backup ( PG_FUNCTION_ARGS )
{
text * backupid = PG_GETARG_TEXT_P ( 0 ) ;
text * result ;
char * backupidstr ;
XLogRecPtr startpoint ;
time_t stamp_time ;
char strfbuf [ 128 ] ;
char labelfilename [ MAXPGPATH ] ;
char xlogfilename [ MAXFNAMELEN ] ;
uint32 _logId ;
uint32 _logSeg ;
struct stat stat_buf ;
FILE * fp ;
if ( ! superuser ( ) )
ereport ( ERROR ,
( errcode ( ERRCODE_INSUFFICIENT_PRIVILEGE ) ,
( errmsg ( " must be superuser to run a backup " ) ) ) ) ;
backupidstr = DatumGetCString ( DirectFunctionCall1 ( textout ,
PointerGetDatum ( backupid ) ) ) ;
/*
* The oldest point in WAL that would be needed to restore starting from
* the most recent checkpoint is precisely the RedoRecPtr .
*/
startpoint = GetRedoRecPtr ( ) ;
XLByteToSeg ( startpoint , _logId , _logSeg ) ;
XLogFileName ( xlogfilename , ThisTimeLineID , _logId , _logSeg ) ;
/*
* We deliberately use strftime / localtime not the src / timezone functions ,
* so that backup labels will consistently be recorded in the same
* timezone regardless of TimeZone setting . This matches elog . c ' s
* practice .
*/
stamp_time = time ( NULL ) ;
strftime ( strfbuf , sizeof ( strfbuf ) ,
" %Y-%m-%d %H:%M:%S %Z " ,
localtime ( & stamp_time ) ) ;
/*
* Check for existing backup label - - - implies a backup is already running
*/
snprintf ( labelfilename , MAXPGPATH , " %s/backup_label " , DataDir ) ;
if ( stat ( labelfilename , & stat_buf ) ! = 0 )
{
if ( errno ! = ENOENT )
ereport ( ERROR ,
( errcode_for_file_access ( ) ,
errmsg ( " could not stat \" %s \" : %m " ,
labelfilename ) ) ) ;
}
else
ereport ( ERROR ,
( errcode ( ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE ) ,
errmsg ( " a backup is already in progress " ) ,
errhint ( " If you're sure there is no backup in progress, remove file \" %s \" and try again. " ,
labelfilename ) ) ) ;
/*
* Okay , write the file
*/
fp = AllocateFile ( labelfilename , " w " ) ;
if ( ! fp )
ereport ( ERROR ,
( errcode_for_file_access ( ) ,
errmsg ( " could not create file \" %s \" : %m " ,
labelfilename ) ) ) ;
fprintf ( fp , " START WAL LOCATION: %X/%X (file %s) \n " ,
startpoint . xlogid , startpoint . xrecoff , xlogfilename ) ;
fprintf ( fp , " START TIME: %s \n " , strfbuf ) ;
fprintf ( fp , " LABEL: %s \n " , backupidstr ) ;
if ( fflush ( fp ) | | ferror ( fp ) | | FreeFile ( fp ) )
ereport ( ERROR ,
( errcode_for_file_access ( ) ,
errmsg ( " could not write file \" %s \" : %m " ,
labelfilename ) ) ) ;
/*
* We ' re done . As a convenience , return the starting WAL offset .
*/
snprintf ( xlogfilename , sizeof ( xlogfilename ) , " %X/%X " ,
startpoint . xlogid , startpoint . xrecoff ) ;
result = DatumGetTextP ( DirectFunctionCall1 ( textin ,
CStringGetDatum ( xlogfilename ) ) ) ;
PG_RETURN_TEXT_P ( result ) ;
}
/*
* pg_stop_backup : finish taking an on - line backup dump
*
* We remove the backup label file created by pg_start_backup , and instead
* create a backup history file in pg_xlog ( whence it will immediately be
* archived ) . The backup history file contains the same info found in
* the label file , plus the backup - end time and WAL offset .
*/
Datum
pg_stop_backup ( PG_FUNCTION_ARGS )
{
text * result ;
XLogCtlInsert * Insert = & XLogCtl - > Insert ;
XLogRecPtr startpoint ;
XLogRecPtr stoppoint ;
time_t stamp_time ;
char strfbuf [ 128 ] ;
char labelfilename [ MAXPGPATH ] ;
char histfilename [ MAXPGPATH ] ;
char startxlogfilename [ MAXFNAMELEN ] ;
char stopxlogfilename [ MAXFNAMELEN ] ;
uint32 _logId ;
uint32 _logSeg ;
FILE * lfp ;
FILE * fp ;
char ch ;
int ich ;
if ( ! superuser ( ) )
ereport ( ERROR ,
( errcode ( ERRCODE_INSUFFICIENT_PRIVILEGE ) ,
( errmsg ( " must be superuser to run a backup " ) ) ) ) ;
/*
* Get the current end - of - WAL position ; it will be unsafe to use this
* dump to restore to a point in advance of this time .
*/
LWLockAcquire ( WALInsertLock , LW_EXCLUSIVE ) ;
INSERT_RECPTR ( stoppoint , Insert , Insert - > curridx ) ;
LWLockRelease ( WALInsertLock ) ;
XLByteToSeg ( stoppoint , _logId , _logSeg ) ;
XLogFileName ( stopxlogfilename , ThisTimeLineID , _logId , _logSeg ) ;
/*
* We deliberately use strftime / localtime not the src / timezone functions ,
* so that backup labels will consistently be recorded in the same
* timezone regardless of TimeZone setting . This matches elog . c ' s
* practice .
*/
stamp_time = time ( NULL ) ;
strftime ( strfbuf , sizeof ( strfbuf ) ,
" %Y-%m-%d %H:%M:%S %Z " ,
localtime ( & stamp_time ) ) ;
/*
* Open the existing label file
*/
snprintf ( labelfilename , MAXPGPATH , " %s/backup_label " , DataDir ) ;
lfp = AllocateFile ( labelfilename , " r " ) ;
if ( ! lfp )
{
if ( errno ! = ENOENT )
ereport ( ERROR ,
( errcode_for_file_access ( ) ,
errmsg ( " could not read file \" %s \" : %m " ,
labelfilename ) ) ) ;
ereport ( ERROR ,
( errcode ( ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE ) ,
errmsg ( " a backup is not in progress " ) ) ) ;
}
/*
* Read and parse the START WAL LOCATION line ( this code is pretty
* crude , but we are not expecting any variability in the file format ) .
*/
if ( fscanf ( lfp , " START WAL LOCATION: %X/%X (file %24s)%c " ,
& startpoint . xlogid , & startpoint . xrecoff , startxlogfilename ,
& ch ) ! = 4 | | ch ! = ' \n ' )
ereport ( ERROR ,
( errcode ( ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE ) ,
errmsg ( " invalid data in file \" %s \" " , labelfilename ) ) ) ;
/*
* Write the backup history file
*/
XLByteToSeg ( startpoint , _logId , _logSeg ) ;
BackupHistoryFilePath ( histfilename , ThisTimeLineID , _logId , _logSeg ,
startpoint . xrecoff % XLogSegSize ) ;
fp = AllocateFile ( histfilename , " w " ) ;
if ( ! fp )
ereport ( ERROR ,
( errcode_for_file_access ( ) ,
errmsg ( " could not create file \" %s \" : %m " ,
histfilename ) ) ) ;
fprintf ( fp , " START WAL LOCATION: %X/%X (file %s) \n " ,
startpoint . xlogid , startpoint . xrecoff , startxlogfilename ) ;
fprintf ( fp , " STOP WAL LOCATION: %X/%X (file %s) \n " ,
stoppoint . xlogid , stoppoint . xrecoff , stopxlogfilename ) ;
/* transfer start time and label lines from label to history file */
while ( ( ich = fgetc ( lfp ) ) ! = EOF )
fputc ( ich , fp ) ;
fprintf ( fp , " STOP TIME: %s \n " , strfbuf ) ;
if ( fflush ( fp ) | | ferror ( fp ) | | FreeFile ( fp ) )
ereport ( ERROR ,
( errcode_for_file_access ( ) ,
errmsg ( " could not write file \" %s \" : %m " ,
histfilename ) ) ) ;
/*
* Close and remove the backup label file
*/
if ( ferror ( lfp ) | | FreeFile ( lfp ) )
ereport ( ERROR ,
( errcode_for_file_access ( ) ,
errmsg ( " could not read file \" %s \" : %m " ,
labelfilename ) ) ) ;
if ( unlink ( labelfilename ) ! = 0 )
ereport ( ERROR ,
( errcode_for_file_access ( ) ,
errmsg ( " could not remove file \" %s \" : %m " ,
labelfilename ) ) ) ;
/*
* Notify archiver that history file may be archived immediately
*/
if ( XLogArchivingActive ( ) )
{
BackupHistoryFileName ( histfilename , ThisTimeLineID , _logId , _logSeg ,
startpoint . xrecoff % XLogSegSize ) ;
XLogArchiveNotify ( histfilename ) ;
}
/*
* We ' re done . As a convenience , return the ending WAL offset .
*/
snprintf ( stopxlogfilename , sizeof ( stopxlogfilename ) , " %X/%X " ,
stoppoint . xlogid , stoppoint . xrecoff ) ;
result = DatumGetTextP ( DirectFunctionCall1 ( textin ,
CStringGetDatum ( stopxlogfilename ) ) ) ;
PG_RETURN_TEXT_P ( result ) ;
}
Tom Lane
21 years ago