From 35216a217af6c3452e9cd70b10963c238bcee9ff Mon Sep 17 00:00:00 2001
From: Alvaro Herrera <alvherre@alvh.no-ip.org>
Date: Mon, 27 Jan 2020 14:43:17 -0300
Subject: [PATCH v2] Use CheckPoint->time to update latest recovery timestamp
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Previously, only timestamps carried by transaction commit/abort and
recovery labels were used, but there's no reason to ignore checkpoint's.

Also, rearrange things so that the timestamp is updated by StartupXLOG's
loop rather than recoveryStopsAfter, which was an odd choice.

Author: Álvaro Herrera
Reviewed-by:
Discussion: https://postgr.es/m/20200110140828.GA6228@alvherre.pgsql
---
 src/backend/access/transam/xlog.c | 37 ++++++++++++++++++++++---------
 1 file changed, 26 insertions(+), 11 deletions(-)

diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 882d5e8a73..0bc3d8cec5 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -5560,8 +5560,8 @@ exitArchiveRecovery(TimeLineID endTLI, XLogRecPtr endOfLog)
  *
  * If the record contains a timestamp, returns true, and saves the timestamp
  * in *recordXtime. If the record type has no timestamp, returns false.
- * Currently, only transaction commit/abort records and restore points contain
- * timestamps.
+ * Currently, only transaction commit/abort records, restore points and
+ * checkpoints contain timestamps.
  */
 static bool
 getRecordTimestamp(XLogReaderState *record, TimestampTz *recordXtime)
@@ -5575,6 +5575,13 @@ getRecordTimestamp(XLogReaderState *record, TimestampTz *recordXtime)
 		*recordXtime = ((xl_restore_point *) XLogRecGetData(record))->rp_time;
 		return true;
 	}
+	if (rmid == RM_XLOG_ID && (info == XLOG_CHECKPOINT_ONLINE ||
+							   info == XLOG_CHECKPOINT_SHUTDOWN))
+	{
+		*recordXtime =
+			time_t_to_timestamptz(((CheckPoint *) XLogRecGetData(record))->time);
+		return true;
+	}
 	if (rmid == RM_XACT_ID && (xact_info == XLOG_XACT_COMMIT ||
 							   xact_info == XLOG_XACT_COMMIT_PREPARED))
 	{
@@ -5743,9 +5750,6 @@ recoveryStopsBefore(XLogReaderState *record)
 
 /*
  * Same as recoveryStopsBefore, but called after applying the record.
- *
- * We also track the timestamp of the latest applied COMMIT/ABORT
- * record in XLogCtl->recoveryLastXTime.
  */
 static bool
 recoveryStopsAfter(XLogReaderState *record)
@@ -5753,7 +5757,6 @@ recoveryStopsAfter(XLogReaderState *record)
 	uint8		info;
 	uint8		xact_info;
 	uint8		rmid;
-	TimestampTz recordXtime;
 
 	/*
 	 * Ignore recovery target settings when not in archive recovery (meaning
@@ -5821,10 +5824,6 @@ recoveryStopsAfter(XLogReaderState *record)
 	{
 		TransactionId recordXid;
 
-		/* Update the last applied transaction timestamp */
-		if (getRecordTimestamp(record, &recordXtime))
-			SetLatestXTime(recordXtime);
-
 		/* Extract the XID of the committed/aborted transaction */
 		if (xact_info == XLOG_XACT_COMMIT_PREPARED)
 		{
@@ -5863,7 +5862,7 @@ recoveryStopsAfter(XLogReaderState *record)
 		{
 			recoveryStopAfter = true;
 			recoveryStopXid = recordXid;
-			recoveryStopTime = recordXtime;
+			getRecordTimestamp(record, &recoveryStopTime);
 			recoveryStopLSN = InvalidXLogRecPtr;
 			recoveryStopName[0] = '\0';
 
@@ -6047,6 +6046,19 @@ recoveryApplyDelay(XLogReaderState *record)
 	return true;
 }
 
+/*
+ * Track the timestamp of the latest applied time-bearing WAL record in
+ * XLogCtl->recoveryLastXTime.
+ */
+static void
+updateRecoveryXTime(XLogReaderState *record)
+{
+	TimestampTz	recordXtime;
+
+	if (getRecordTimestamp(record, &recordXtime))
+		SetLatestXTime(recordXtime);
+}
+
 /*
  * Save timestamp of latest processed commit/abort record.
  *
@@ -7255,6 +7267,9 @@ StartupXLOG(void)
 						WalSndWakeup();
 				}
 
+				/* update last recovery time */
+				updateRecoveryXTime(xlogreader);
+
 				/* Exit loop if we reached inclusive recovery target */
 				if (recoveryStopsAfter(xlogreader))
 				{
-- 
2.20.1