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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.
This commit is contained in:
Heikki Linnakangas
2013-01-03 10:41:58 +02:00
parent bcbe99244f
commit ee994272ca
2 changed files with 89 additions and 54 deletions
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5
src/backend/replication/walreceiver.c
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@ -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;