diff --git a/doc/src/sgml/protocol.sgml b/doc/src/sgml/protocol.sgml
index 1a75059370..d32626677d 100644
--- a/doc/src/sgml/protocol.sgml
+++ b/doc/src/sgml/protocol.sgml
@@ -1682,8 +1682,10 @@ The commands accepted in walsender mode are:
- The standby's current xmin. This may be 0, if the standby does not
- support feedback, or is not yet in Hot Standby state.
+ The standby's current xmin. This may be 0, if the standby is
+ sending notification that Hot Standby feedback will no longer
+ be sent on this connection. Later non-zero messages may
+ reinitiate the feedback mechanism.
diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index 73592973ac..37d5e0821e 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -47,6 +47,7 @@
#include
#include "access/timeline.h"
+#include "access/transam.h"
#include "access/xlog_internal.h"
#include "libpq/pqformat.h"
#include "libpq/pqsignal.h"
@@ -138,7 +139,7 @@ static void XLogWalRcvProcessMsg(unsigned char type, char *buf, Size len);
static void XLogWalRcvWrite(char *buf, Size nbytes, XLogRecPtr recptr);
static void XLogWalRcvFlush(bool dying);
static void XLogWalRcvSendReply(bool force, bool requestReply);
-static void XLogWalRcvSendHSFeedback(void);
+static void XLogWalRcvSendHSFeedback(bool immed);
static void ProcessWalSndrMessage(XLogRecPtr walEnd, TimestampTz sendTime);
/* Signal handlers */
@@ -406,6 +407,7 @@ WalReceiverMain(void)
{
got_SIGHUP = false;
ProcessConfigFile(PGC_SIGHUP);
+ XLogWalRcvSendHSFeedback(true);
}
/* Wait a while for data to arrive */
@@ -496,7 +498,7 @@ WalReceiverMain(void)
}
XLogWalRcvSendReply(requestReply, requestReply);
- XLogWalRcvSendHSFeedback();
+ XLogWalRcvSendHSFeedback(false);
}
}
@@ -1059,46 +1061,60 @@ XLogWalRcvSendReply(bool force, bool requestReply)
/*
* Send hot standby feedback message to primary, plus the current time,
* in case they don't have a watch.
+ *
+ * If the user disables feedback, send one final message to tell sender
+ * to forget about the xmin on this standby.
*/
static void
-XLogWalRcvSendHSFeedback(void)
+XLogWalRcvSendHSFeedback(bool immed)
{
TimestampTz now;
TransactionId nextXid;
uint32 nextEpoch;
TransactionId xmin;
static TimestampTz sendTime = 0;
+ static bool master_has_standby_xmin = false;
/*
* If the user doesn't want status to be reported to the master, be sure
* to exit before doing anything at all.
*/
- if (wal_receiver_status_interval <= 0 || !hot_standby_feedback)
+ if ((wal_receiver_status_interval <= 0 || !hot_standby_feedback) &&
+ !master_has_standby_xmin)
return;
/* Get current timestamp. */
now = GetCurrentTimestamp();
- /*
- * Send feedback at most once per wal_receiver_status_interval.
- */
- if (!TimestampDifferenceExceeds(sendTime, now,
+ if (!immed)
+ {
+ /*
+ * Send feedback at most once per wal_receiver_status_interval.
+ */
+ if (!TimestampDifferenceExceeds(sendTime, now,
wal_receiver_status_interval * 1000))
- return;
- sendTime = now;
+ return;
+ sendTime = now;
+ }
/*
* If Hot Standby is not yet active there is nothing to send. Check this
* after the interval has expired to reduce number of calls.
*/
if (!HotStandbyActive())
+ {
+ Assert(!master_has_standby_xmin);
return;
+ }
/*
* Make the expensive call to get the oldest xmin once we are certain
* everything else has been checked.
*/
- xmin = GetOldestXmin(true, false);
+ if (hot_standby_feedback)
+ xmin = GetOldestXmin(true, false);
+ else
+ xmin = InvalidTransactionId;
/*
* Get epoch and adjust if nextXid and oldestXmin are different sides of
@@ -1118,6 +1134,10 @@ XLogWalRcvSendHSFeedback(void)
pq_sendint(&reply_message, xmin, 4);
pq_sendint(&reply_message, nextEpoch, 4);
walrcv_send(reply_message.data, reply_message.len);
+ if (TransactionIdIsValid(xmin))
+ master_has_standby_xmin = true;
+ else
+ master_has_standby_xmin = false;
}
/*
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 10e4050696..490b121362 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -870,9 +870,12 @@ ProcessStandbyHSFeedbackMessage(void)
feedbackXmin,
feedbackEpoch);
- /* Ignore invalid xmin (can't actually happen with current walreceiver) */
+ /* Unset WalSender's xmin if the feedback message value is invalid */
if (!TransactionIdIsNormal(feedbackXmin))
+ {
+ MyPgXact->xmin = InvalidTransactionId;
return;
+ }
/*
* Check that the provided xmin/epoch are sane, that is, not in the future