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Delay reading timeline history file until it's fetched from master.

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Streaming replication can fetch any missing timeline history files from the
master, but recovery would read the timeline history file for the target
timeline before reading the checkpoint record, and before walreceiver has
had a chance to fetch it from the master. Delay reading it, and the sanity
checks involving timeline history, until after reading the checkpoint
record.

There is at least one scenario where this makes a difference: if you take
a base backup from a standby server right after a timeline switch, the
WAL segment containing the initial checkpoint record will begin with an
older timeline ID. Without the timeline history file, recovering that file
will fail as the older timeline ID is not recognized to be an ancestor of
the target timeline. If you try to recover from such a backup, using only
streaming replication to fetch the WAL, this patch is required for that to
work.
pull/3/head
Heikki Linnakangas 13 years ago
parent bcbe99244f
commit ee994272ca
2 changed files with 90 additions and 55 deletions
Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL
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  1. 140
      src/backend/access/transam/xlog.c
  2. 5
      src/backend/replication/walreceiver.c

140
src/backend/access/transam/xlog.c
Unescape View File

@ -2675,6 +2675,7 @@ XLogFileReadAnyTLI(XLogSegNo segno, int emode, int source)
char path[MAXPGPATH];
ListCell *cell;
int fd;
List *tles;
/*
* Loop looking for a suitable timeline ID: we might need to read any of
@ -2685,8 +2686,21 @@ XLogFileReadAnyTLI(XLogSegNo segno, int emode, int source)
* to go backwards; this prevents us from picking up the wrong file when a
* parent timeline extends to higher segment numbers than the child we
* want to read.
*/
foreach(cell, expectedTLEs)
*
* If we haven't read the timeline history file yet, read it now, so that
* we know which TLIs to scan. We don't save the list in expectedTLEs,
* however, unless we actually find a valid segment. That way if there is
* neither a timeline history file nor a WAL segment in the archive, and
* streaming replication is set up, we'll read the timeline history file
* streamed from the master when we start streaming, instead of recovering
* with a dummy history generated here.
*/
if (expectedTLEs)
tles = expectedTLEs;
else
tles = readTimeLineHistory(recoveryTargetTLI);
foreach(cell, tles)
{
TimeLineID tli = ((TimeLineHistoryEntry *) lfirst(cell))->tli;
@ -2699,6 +2713,8 @@ XLogFileReadAnyTLI(XLogSegNo segno, int emode, int source)
if (fd != -1)
{
elog(DEBUG1, "got WAL segment from archive");
if (!expectedTLEs)
expectedTLEs = tles;
return fd;
}
}
@ -2707,7 +2723,11 @@ XLogFileReadAnyTLI(XLogSegNo segno, int emode, int source)
{
fd = XLogFileRead(segno, emode, tli, XLOG_FROM_PG_XLOG, true);
if (fd != -1)
{
if (!expectedTLEs)
expectedTLEs = tles;
return fd;
}
}
}
@ -5279,49 +5299,6 @@ StartupXLOG(void)
*/
readRecoveryCommandFile();
/* Now we can determine the list of expected TLIs */
expectedTLEs = readTimeLineHistory(recoveryTargetTLI);
/*
* If the location of the checkpoint record is not on the expected
* timeline in the history of the requested timeline, we cannot proceed:
* the backup is not part of the history of the requested timeline.
*/
if (tliOfPointInHistory(ControlFile->checkPoint, expectedTLEs) !=
ControlFile->checkPointCopy.ThisTimeLineID)
{
XLogRecPtr switchpoint;
/*
* tliSwitchPoint will throw an error if the checkpoint's timeline
* is not in expectedTLEs at all.
*/
switchpoint = tliSwitchPoint(ControlFile->checkPointCopy.ThisTimeLineID, expectedTLEs);
ereport(FATAL,
(errmsg("requested timeline %u is not a child of this server's history",
recoveryTargetTLI),
errdetail("Latest checkpoint is at %X/%X on timeline %u, but in the history of the requested timeline, the server forked off from that timeline at %X/%X",
(uint32) (ControlFile->checkPoint >> 32),
(uint32) ControlFile->checkPoint,
ControlFile->checkPointCopy.ThisTimeLineID,
(uint32) (switchpoint >> 32),
(uint32) switchpoint)));
}
/*
* The min recovery point should be part of the requested timeline's
* history, too.
*/
if (!XLogRecPtrIsInvalid(ControlFile->minRecoveryPoint) &&
tliOfPointInHistory(ControlFile->minRecoveryPoint - 1, expectedTLEs) !=
ControlFile->minRecoveryPointTLI)
ereport(FATAL,
(errmsg("requested timeline %u does not contain minimum recovery point %X/%X on timeline %u",
recoveryTargetTLI,
(uint32) (ControlFile->minRecoveryPoint >> 32),
(uint32) ControlFile->minRecoveryPoint,
ControlFile->minRecoveryPointTLI)));
/*
* Save archive_cleanup_command in shared memory so that other processes
* can see it.
@ -5443,6 +5420,47 @@ StartupXLOG(void)
wasShutdown = (record->xl_info == XLOG_CHECKPOINT_SHUTDOWN);
}
/*
* If the location of the checkpoint record is not on the expected
* timeline in the history of the requested timeline, we cannot proceed:
* the backup is not part of the history of the requested timeline.
*/
Assert(expectedTLEs); /* was initialized by reading checkpoint record */
if (tliOfPointInHistory(checkPointLoc, expectedTLEs) !=
checkPoint.ThisTimeLineID)
{
XLogRecPtr switchpoint;
/*
* tliSwitchPoint will throw an error if the checkpoint's timeline
* is not in expectedTLEs at all.
*/
switchpoint = tliSwitchPoint(ControlFile->checkPointCopy.ThisTimeLineID, expectedTLEs);
ereport(FATAL,
(errmsg("requested timeline %u is not a child of this server's history",
recoveryTargetTLI),
errdetail("Latest checkpoint is at %X/%X on timeline %u, but in the history of the requested timeline, the server forked off from that timeline at %X/%X",
(uint32) (ControlFile->checkPoint >> 32),
(uint32) ControlFile->checkPoint,
ControlFile->checkPointCopy.ThisTimeLineID,
(uint32) (switchpoint >> 32),
(uint32) switchpoint)));
}
/*
* The min recovery point should be part of the requested timeline's
* history, too.
*/
if (!XLogRecPtrIsInvalid(ControlFile->minRecoveryPoint) &&
tliOfPointInHistory(ControlFile->minRecoveryPoint - 1, expectedTLEs) !=
ControlFile->minRecoveryPointTLI)
ereport(FATAL,
(errmsg("requested timeline %u does not contain minimum recovery point %X/%X on timeline %u",
recoveryTargetTLI,
(uint32) (ControlFile->minRecoveryPoint >> 32),
(uint32) ControlFile->minRecoveryPoint,
ControlFile->minRecoveryPointTLI)));
LastRec = RecPtr = checkPointLoc;
ereport(DEBUG1,
@ -9569,13 +9587,24 @@ WaitForWALToBecomeAvailable(XLogRecPtr RecPtr, bool randAccess,
*/
if (PrimaryConnInfo)
{
XLogRecPtr ptr = fetching_ckpt ? RedoStartLSN : RecPtr;
TimeLineID tli = tliOfPointInHistory(ptr, expectedTLEs);
XLogRecPtr ptr;
TimeLineID tli;
if (curFileTLI > 0 && tli < curFileTLI)
elog(ERROR, "according to history file, WAL location %X/%X belongs to timeline %u, but previous recovered WAL file came from timeline %u",
(uint32) (ptr >> 32), (uint32) ptr,
tli, curFileTLI);
if (fetching_ckpt)
{
ptr = RedoStartLSN;
tli = ControlFile->checkPointCopy.ThisTimeLineID;
}
else
{
ptr = RecPtr;
tli = tliOfPointInHistory(ptr, expectedTLEs);
if (curFileTLI > 0 && tli < curFileTLI)
elog(ERROR, "according to history file, WAL location %X/%X belongs to timeline %u, but previous recovered WAL file came from timeline %u",
(uint32) (ptr >> 32), (uint32) ptr,
tli, curFileTLI);
}
curFileTLI = tli;
RequestXLogStreaming(curFileTLI, ptr, PrimaryConnInfo);
}
@ -9739,11 +9768,16 @@ WaitForWALToBecomeAvailable(XLogRecPtr RecPtr, bool randAccess,
{
/*
* Great, streamed far enough. Open the file if it's not
* open already. Use XLOG_FROM_STREAM so that source info
* is set correctly and XLogReceiptTime isn't changed.
* open already. Also read the timeline history file if
* we haven't initialized timeline history yet; it should
* be streamed over and present in pg_xlog by now. Use
* XLOG_FROM_STREAM so that source info is set correctly
* and XLogReceiptTime isn't changed.
*/
if (readFile < 0)
{
if (!expectedTLEs)
expectedTLEs = readTimeLineHistory(receiveTLI);
readFile = XLogFileRead(readSegNo, PANIC,
receiveTLI,
XLOG_FROM_STREAM, false);

5
src/backend/replication/walreceiver.c
Unescape View File

@ -338,7 +338,7 @@ WalReceiverMain(void)
* ensure that a unique timeline id is chosen in every case, but let's
* avoid the confusion of timeline id collisions where we can.
*/
WalRcvFetchTimeLineHistoryFiles(startpointTLI + 1, primaryTLI);
WalRcvFetchTimeLineHistoryFiles(startpointTLI, primaryTLI);
/*
* Start streaming.
@ -627,7 +627,8 @@ WalRcvFetchTimeLineHistoryFiles(TimeLineID first, TimeLineID last)
for (tli = first; tli <= last; tli++)
{
if (!existsTimeLineHistory(tli))
/* there's no history file for timeline 1 */
if (tli != 1 && !existsTimeLineHistory(tli))
{
char *fname;
char *content;

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