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Make pg_receivexlog and pg_basebackup -X stream work across timeline switches.

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This mirrors the changes done earlier to the server in standby mode. When
receivelog reaches the end of a timeline, as reported by the server, it
fetches the timeline history file of the next timeline, and restarts
streaming from the new timeline by issuing a new START_STREAMING command.

When pg_receivexlog crosses a timeline, it leaves the .partial suffix on the
last segment on the old timeline. This helps you to tell apart a partial
segment left in the directory because of a timeline switch, and a completed
segment. If you just follow a single server, it won't make a difference, but
it can be significant in more complicated scenarios where new WAL is still
generated on the old timeline.

This includes two small changes to the streaming replication protocol:
First, when you reach the end of timeline while streaming, the server now
sends the TLI of the next timeline in the server's history to the client.
pg_receivexlog uses that as the next timeline, so that it doesn't need to
parse the timeline history file like a standby server does. Second, when
BASE_BACKUP command sends the begin and end WAL positions, it now also sends
the timeline IDs corresponding the positions.
This commit is contained in:
Heikki Linnakangas
2013-01-17 20:23:00 +02:00
parent 8ae35e9180
commit 0b6329130e
12 changed files with 699 additions and 312 deletions
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14
src/backend/access/transam/timeline.c
View File

@@ -545,22 +545,26 @@ tliOfPointInHistory(XLogRecPtr ptr, List *history)
}
/*
* Returns the point in history where we branched off the given timeline.
* Returns InvalidXLogRecPtr if the timeline is current (= we have not
* branched off from it), and throws an error if the timeline is not part of
* this server's history.
* Returns the point in history where we branched off the given timeline,
* and the timeline we branched to (*nextTLI). Returns InvalidXLogRecPtr if
* the timeline is current, ie. we have not branched off from it, and throws
* an error if the timeline is not part of this server's history.
*/
XLogRecPtr
tliSwitchPoint(TimeLineID tli, List *history)
tliSwitchPoint(TimeLineID tli, List *history, TimeLineID *nextTLI)
{
ListCell *cell;
if (nextTLI)
*nextTLI = 0;
foreach (cell, history)
{
TimeLineHistoryEntry *tle = (TimeLineHistoryEntry *) lfirst(cell);
if (tle->tli == tli)
return tle->end;
if (nextTLI)
*nextTLI = tle->tli;
}
ereport(ERROR,

24
src/backend/access/transam/xlog.c
View File

@@ -4930,7 +4930,7 @@ StartupXLOG(void)
* tliSwitchPoint will throw an error if the checkpoint's timeline
* is not in expectedTLEs at all.
*/
switchpoint = tliSwitchPoint(ControlFile->checkPointCopy.ThisTimeLineID, expectedTLEs);
switchpoint = tliSwitchPoint(ControlFile->checkPointCopy.ThisTimeLineID, expectedTLEs, NULL);
ereport(FATAL,
(errmsg("requested timeline %u is not a child of this server's history",
recoveryTargetTLI),
@@ -7870,16 +7870,21 @@ XLogFileNameP(TimeLineID tli, XLogSegNo segno)
* non-exclusive backups active at the same time, and they don't conflict
* with an exclusive backup either.
*
* Returns the minimum WAL position that must be present to restore from this
* backup, and the corresponding timeline ID in *starttli_p.
*
* Every successfully started non-exclusive backup must be stopped by calling
* do_pg_stop_backup() or do_pg_abort_backup().
*/
XLogRecPtr
do_pg_start_backup(const char *backupidstr, bool fast, char **labelfile)
do_pg_start_backup(const char *backupidstr, bool fast, TimeLineID *starttli_p,
char **labelfile)
{
bool exclusive = (labelfile == NULL);
bool backup_started_in_recovery = false;
XLogRecPtr checkpointloc;
XLogRecPtr startpoint;
TimeLineID starttli;
pg_time_t stamp_time;
char strfbuf[128];
char xlogfilename[MAXFNAMELEN];
@@ -8021,6 +8026,7 @@ do_pg_start_backup(const char *backupidstr, bool fast, char **labelfile)
LWLockAcquire(ControlFileLock, LW_SHARED);
checkpointloc = ControlFile->checkPoint;
startpoint = ControlFile->checkPointCopy.redo;
starttli = ControlFile->checkPointCopy.ThisTimeLineID;
checkpointfpw = ControlFile->checkPointCopy.fullPageWrites;
LWLockRelease(ControlFileLock);
@@ -8154,6 +8160,8 @@ do_pg_start_backup(const char *backupidstr, bool fast, char **labelfile)
/*
* We're done. As a convenience, return the starting WAL location.
*/
if (starttli_p)
*starttli_p = starttli;
return startpoint;
}
@@ -8190,14 +8198,18 @@ pg_start_backup_callback(int code, Datum arg)
* If labelfile is NULL, this stops an exclusive backup. Otherwise this stops
* the non-exclusive backup specified by 'labelfile'.
*
* Returns the last WAL position that must be present to restore from this
* backup, and the corresponding timeline ID in *stoptli_p.
*/
XLogRecPtr
do_pg_stop_backup(char *labelfile, bool waitforarchive)
do_pg_stop_backup(char *labelfile, bool waitforarchive, TimeLineID *stoptli_p)
{
bool exclusive = (labelfile == NULL);
bool backup_started_in_recovery = false;
XLogRecPtr startpoint;
XLogRecPtr stoppoint;
TimeLineID stoptli;
XLogRecData rdata;
pg_time_t stamp_time;
char strfbuf[128];
@@ -8401,8 +8413,11 @@ do_pg_stop_backup(char *labelfile, bool waitforarchive)
LWLockAcquire(ControlFileLock, LW_SHARED);
stoppoint = ControlFile->minRecoveryPoint;
stoptli = ControlFile->minRecoveryPointTLI;
LWLockRelease(ControlFileLock);
if (stoptli_p)
*stoptli_p = stoptli;
return stoppoint;
}
@@ -8414,6 +8429,7 @@ do_pg_stop_backup(char *labelfile, bool waitforarchive)
rdata.buffer = InvalidBuffer;
rdata.next = NULL;
stoppoint = XLogInsert(RM_XLOG_ID, XLOG_BACKUP_END, &rdata);
stoptli = ThisTimeLineID;
/*
* Force a switch to a new xlog segment file, so that the backup is valid
@@ -8529,6 +8545,8 @@ do_pg_stop_backup(char *labelfile, bool waitforarchive)
/*
* We're done. As a convenience, return the ending WAL location.
*/
if (stoptli_p)
*stoptli_p = stoptli;
return stoppoint;
}

4
src/backend/access/transam/xlogfuncs.c
View File

@@ -56,7 +56,7 @@ pg_start_backup(PG_FUNCTION_ARGS)
backupidstr = text_to_cstring(backupid);
startpoint = do_pg_start_backup(backupidstr, fast, NULL);
startpoint = do_pg_start_backup(backupidstr, fast, NULL, NULL);
snprintf(startxlogstr, sizeof(startxlogstr), "%X/%X",
(uint32) (startpoint >> 32), (uint32) startpoint);
@@ -82,7 +82,7 @@ pg_stop_backup(PG_FUNCTION_ARGS)
XLogRecPtr stoppoint;
char stopxlogstr[MAXFNAMELEN];
stoppoint = do_pg_stop_backup(NULL, true);
stoppoint = do_pg_stop_backup(NULL, true, NULL);
snprintf(stopxlogstr, sizeof(stopxlogstr), "%X/%X",
(uint32) (stoppoint >> 32), (uint32) stoppoint);