Hello
Sorry for late replies.
> Yes. In my opinion, patch 0002 should not change the GUC mode of
> wal_receiver_create_temp_slot as the discussion here is about
> primary_conninfo, even if both may share some logic regarding WAL
> receiver shutdown and its restart triggered by the startup process.
Ok, I removed related changes from main patch. Along with minor merge conflict.
> Patch 0001 has actually been presented on this thread first:
> https://www.postgresql.org/message-id/753391579708...@iva3-77ae5995f07f.qloud-c.yandex.net
> And there is an independent patch registered in this CF:
> https://commitfest.postgresql.org/27/2456/
Yep, 0001 is separate patch. I will post copy of this patch here to make cfbot
works. Main patch 0002 requires resetting of is_temp_slot in
RequestXLogStreaming to works properly.
> Should we add patch 0001 as an open item for v13 as there is a risk of
> forgetting this issue?
I think yes.
Well, it seems better to move this patch to next commitfest?
regards, Sergei
diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h
index 98b033fc20..12362421d7 100644
--- a/src/include/access/xlog.h
+++ b/src/include/access/xlog.h
@@ -129,6 +129,7 @@ extern int recoveryTargetAction;
extern int recovery_min_apply_delay;
extern char *PrimaryConnInfo;
extern char *PrimarySlotName;
+extern bool wal_receiver_create_temp_slot;
/* indirectly set via GUC system */
extern TransactionId recoveryTargetXid;
diff --git a/src/include/replication/walreceiver.h b/src/include/replication/walreceiver.h
index e08afc6548..cf3e43128c 100644
--- a/src/include/replication/walreceiver.h
+++ b/src/include/replication/walreceiver.h
@@ -23,7 +23,6 @@
#include "utils/tuplestore.h"
/* user-settable parameters */
-extern bool wal_receiver_create_temp_slot;
extern int wal_receiver_status_interval;
extern int wal_receiver_timeout;
extern bool hot_standby_feedback;
@@ -321,7 +320,8 @@ extern void ShutdownWalRcv(void);
extern bool WalRcvStreaming(void);
extern bool WalRcvRunning(void);
extern void RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr,
- const char *conninfo, const char *slotname);
+ const char *conninfo, const char *slotname,
+ bool create_temp_slot);
extern XLogRecPtr GetWalRcvWriteRecPtr(XLogRecPtr *latestChunkStart, TimeLineID *receiveTLI);
extern int GetReplicationApplyDelay(void);
extern int GetReplicationTransferLatency(void);
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 3813eadfb4..e0f3ed5c2a 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -283,6 +283,7 @@ bool StandbyModeRequested = false;
char *PrimaryConnInfo = NULL;
char *PrimarySlotName = NULL;
char *PromoteTriggerFile = NULL;
+bool wal_receiver_create_temp_slot = false;
/* are we currently in standby mode? */
bool StandbyMode = false;
@@ -11901,7 +11902,7 @@ WaitForWALToBecomeAvailable(XLogRecPtr RecPtr, bool randAccess,
}
curFileTLI = tli;
RequestXLogStreaming(tli, ptr, PrimaryConnInfo,
- PrimarySlotName);
+ PrimarySlotName, wal_receiver_create_temp_slot);
receivedUpto = 0;
}
diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index 2ab15c3cbb..ff45482faa 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -15,6 +15,12 @@
* WalRcv->receivedUpto variable in shared memory, to inform the startup
* process of how far it can proceed with XLOG replay.
*
+ * WAL receivers cannot load directly GUC parameters used when establishing
+ * their connection to the primary, and rely on parameter values passed down
+ * by the startup process when WAL streaming is requested. This applies
+ * to for example the replication slot creation and the connection string to
+ * use for the connection with the primary.
+ *
* If the primary server ends streaming, but doesn't disconnect, walreceiver
* goes into "waiting" mode, and waits for the startup process to give new
* instructions. The startup process will treat that the same as
@@ -73,7 +79,6 @@
/* GUC variables */
-bool wal_receiver_create_temp_slot;
int wal_receiver_status_interval;
int wal_receiver_timeout;
bool hot_standby_feedback;
@@ -348,42 +353,23 @@ WalReceiverMain(void)
WalRcvFetchTimeLineHistoryFiles(startpointTLI, primaryTLI);
/*
- * Create temporary replication slot if no slot name is configured or
- * the slot from the previous run was temporary, unless
- * wal_receiver_create_temp_slot is disabled. We also need to handle
- * the case where the previous run used a temporary slot but
- * wal_receiver_create_temp_slot was changed in the meantime. In that
- * case, we delete the old slot name in shared memory. (This would
+ * Create temporary replication slot if requested. In that
+ * case, we update slot name in shared memory. (This would
* all be a bit easier if we just didn't copy the slot name into
* shared memory, since we won't need it again later, but then we
* can't see the slot name in the stats views.)
*/
- if (slotname[0] == '\0' || is_temp_slot)
+ if (is_temp_slot)
{
- bool changed = false;
+ snprintf(slotname, sizeof(slotname),
+ "pg_walreceiver_%lld",
+ (long long int) walrcv_get_backend_pid(wrconn));
- if (wal_receiver_create_temp_slot)
- {
- snprintf(slotname, sizeof(slotname),
- "pg_walreceiver_%lld",
- (long long int) walrcv_get_backend_pid(wrconn));
+ walrcv_create_slot(wrconn, slotname, true, 0, NULL);
- walrcv_create_slot(wrconn, slotname, true, 0, NULL);
- changed = true;
- }
- else if (slotname[0] != '\0')
- {
- slotname[0] = '\0';
- changed = true;
- }
-
- if (changed)
- {
- SpinLockAcquire(&walrcv->mutex);
- strlcpy(walrcv->slotname, slotname, NAMEDATALEN);
- walrcv->is_temp_slot = wal_receiver_create_temp_slot;
- SpinLockRelease(&walrcv->mutex);
- }
+ SpinLockAcquire(&walrcv->mutex);
+ strlcpy(walrcv->slotname, slotname, NAMEDATALEN);
+ SpinLockRelease(&walrcv->mutex);
}
/*
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 89c903e45a..821680a857 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -215,13 +215,19 @@ ShutdownWalRcv(void)
/*
* Request postmaster to start walreceiver.
*
- * recptr indicates the position where streaming should begin, conninfo
- * is a libpq connection string to use, and slotname is, optionally, the name
- * of a replication slot to acquire.
+ * "recptr" indicates the position where streaming should begin. "conninfo"
+ * is a libpq connection string to use. "slotname" is, optionally, the name
+ * of a replication slot to acquire. "create_temp_slot" indicates to create
+ * a temporary slot when no "slotname" is given.
+ *
+ * WAL receivers do not directly load GUC parameters used for the connection
+ * to the primary, and rely on the values passed down by the caller of this
+ * routine instead. Hence, the addition of any new parameters should happen
+ * through this code path.
*/
void
RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
- const char *slotname)
+ const char *slotname, bool create_temp_slot)
{
WalRcvData *walrcv = WalRcv;
bool launch = false;
@@ -248,10 +254,22 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
else
walrcv->conninfo[0] = '\0';
+ /*
+ * Use configured replication slot if present, and ignore the value
+ * of create_temp_slot as the slot name should be persistent. Otherwise,
+ * use create_temp_slot to determine whether this WAL receiver should
+ * create a temporary slot by itself and use it, or not.
+ */
if (slotname != NULL)
+ {
strlcpy((char *) walrcv->slotname, slotname, NAMEDATALEN);
+ walrcv->is_temp_slot = false;
+ }
else
+ {
walrcv->slotname[0] = '\0';
+ walrcv->is_temp_slot = create_temp_slot;
+ }
if (walrcv->walRcvState == WALRCV_STOPPED)
{
diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index 8228e1f390..ec9cd3696c 100644
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -2029,11 +2029,11 @@ static struct config_bool ConfigureNamesBool[] =
},
{
- {"wal_receiver_create_temp_slot", PGC_SIGHUP, REPLICATION_STANDBY,
+ {"wal_receiver_create_temp_slot", PGC_POSTMASTER, REPLICATION_STANDBY,
gettext_noop("Sets whether a WAL receiver should create a temporary replication slot if no permanent slot is configured."),
},
&wal_receiver_create_temp_slot,
- true,
+ false,
NULL, NULL, NULL
},
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index e1048c0047..1dd2a86567 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -321,7 +321,9 @@
#max_standby_streaming_delay = 30s # max delay before canceling queries
# when reading streaming WAL;
# -1 allows indefinite delay
-#wal_receiver_create_temp_slot = on # create temp slot if primary_slot_name not set
+#wal_receiver_create_temp_slot = off # Create temp slot if primary_slot_name
+ # is not set.
+ # (change requires restart)
#wal_receiver_status_interval = 10s # send replies at least this often
# 0 disables
#hot_standby_feedback = off # send info from standby to prevent
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index c1128f89ec..683d87c491 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4140,11 +4140,7 @@ ANY <replaceable class="parameter">num_sync</replaceable> ( <replaceable class="
Specifies whether a WAL receiver should create a temporary replication
slot on the remote instance when no permanent replication slot to use
has been configured (using <xref linkend="guc-primary-slot-name"/>).
- The default is on. The only reason to turn this off would be if the
- remote instance is currently out of available replication slots. This
- parameter can only be set in the <filename>postgresql.conf</filename>
- file or on the server command line. Changes only take effect when the
- WAL receiver process starts a new connection.
+ The default is off. This parameter can only be set at server start.
</para>
</listitem>
</varlistentry>
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 8b742c83c5..f1d2a77043 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4025,9 +4025,15 @@ ANY <replaceable class="parameter">num_sync</replaceable> ( <replaceable class="
<varname>primary_conninfo</varname> string.
</para>
<para>
- This parameter can only be set at server start.
+ This parameter can only be set in the <filename>postgresql.conf</filename>
+ file or on the server command line.
This setting has no effect if the server is not in standby mode.
</para>
+ <para>
+ If <varname>primary_conninfo</varname> is changed while WAL receiver is running,
+ the WAL receiver shuts down and then restarts with new setting,
+ except when primary_conninfo is an empty string.
+ </para>
</listitem>
</varlistentry>
<varlistentry id="guc-primary-slot-name" xreflabel="primary_slot_name">
@@ -4042,9 +4048,13 @@ ANY <replaceable class="parameter">num_sync</replaceable> ( <replaceable class="
connecting to the sending server via streaming replication to control
resource removal on the upstream node
(see <xref linkend="streaming-replication-slots"/>).
- This parameter can only be set at server start.
+ This parameter can only be set in the <filename>postgresql.conf</filename>
+ file or on the server command line.
This setting has no effect if <varname>primary_conninfo</varname> is not
- set.
+ set or the server is not in standby mode.
+ </para>
+ <para>
+ The WAL receiver is restarted after an update of <varname>primary_slot_name</varname>.
</para>
</listitem>
</varlistentry>
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 483fedb218..e1f3e905bb 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -808,6 +808,12 @@ static XLogSource readSource = XLOG_FROM_ANY;
static XLogSource currentSource = XLOG_FROM_ANY;
static bool lastSourceFailed = false;
+/*
+ * Need for restart running WalReceiver due the configuration change.
+ * Suitable only for XLOG_FROM_STREAM source
+ */
+static bool pendingWalRcvRestart = false;
+
typedef struct XLogPageReadPrivate
{
int emode;
@@ -11881,6 +11887,7 @@ WaitForWALToBecomeAvailable(XLogRecPtr RecPtr, bool randAccess,
for (;;)
{
XLogSource oldSource = currentSource;
+ bool startWalReceiver = false;
/*
* First check if we failed to read from the current source, and
@@ -11914,54 +11921,13 @@ WaitForWALToBecomeAvailable(XLogRecPtr RecPtr, bool randAccess,
if (!StandbyMode)
return false;
- /*
- * If primary_conninfo is set, launch walreceiver to try
- * to stream the missing WAL.
- *
- * If fetching_ckpt is true, RecPtr points to the initial
- * checkpoint location. In that case, we use RedoStartLSN
- * as the streaming start position instead of RecPtr, so
- * that when we later jump backwards to start redo at
- * RedoStartLSN, we will have the logs streamed already.
- */
- if (PrimaryConnInfo && strcmp(PrimaryConnInfo, "") != 0)
- {
- XLogRecPtr ptr;
- TimeLineID tli;
-
- if (fetching_ckpt)
- {
- ptr = RedoStartLSN;
- tli = ControlFile->checkPointCopy.ThisTimeLineID;
- }
- else
- {
- ptr = RecPtr;
-
- /*
- * Use the record begin position to determine the
- * TLI, rather than the position we're reading.
- */
- tli = tliOfPointInHistory(tliRecPtr, 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) (tliRecPtr >> 32),
- (uint32) tliRecPtr,
- tli, curFileTLI);
- }
- curFileTLI = tli;
- RequestXLogStreaming(tli, ptr, PrimaryConnInfo,
- PrimarySlotName, wal_receiver_create_temp_slot);
- receivedUpto = 0;
- }
-
/*
* Move to XLOG_FROM_STREAM state in either case. We'll
* get immediate failure if we didn't launch walreceiver,
* and move on to the next state.
*/
currentSource = XLOG_FROM_STREAM;
+ startWalReceiver = true;
break;
case XLOG_FROM_STREAM:
@@ -12113,7 +12079,69 @@ WaitForWALToBecomeAvailable(XLogRecPtr RecPtr, bool randAccess,
Assert(StandbyMode);
/*
- * Check if WAL receiver is still active.
+ * shutdown WAL receiver if restart is requested.
+ */
+ if (!startWalReceiver && pendingWalRcvRestart)
+ {
+ if (WalRcvRunning())
+ ShutdownWalRcv();
+
+ /*
+ * Re-scan for possible new timelines if we were
+ * requested to recover to the latest timeline.
+ */
+ if (recoveryTargetTimeLineGoal ==
+ RECOVERY_TARGET_TIMELINE_LATEST)
+ rescanLatestTimeLine();
+
+ startWalReceiver = true;
+ }
+ pendingWalRcvRestart = false;
+
+ /*
+ * Launch walreceiver if needed.
+ *
+ * If fetching_ckpt is true, RecPtr points to the initial
+ * checkpoint location. In that case, we use RedoStartLSN
+ * as the streaming start position instead of RecPtr, so
+ * that when we later jump backwards to start redo at
+ * RedoStartLSN, we will have the logs streamed already.
+ */
+ if (startWalReceiver &&
+ PrimaryConnInfo && strcmp(PrimaryConnInfo, "") != 0)
+ {
+ XLogRecPtr ptr;
+ TimeLineID tli;
+
+ if (fetching_ckpt)
+ {
+ ptr = RedoStartLSN;
+ tli = ControlFile->checkPointCopy.ThisTimeLineID;
+ }
+ else
+ {
+ ptr = RecPtr;
+
+ /*
+ * Use the record begin position to determine the
+ * TLI, rather than the position we're reading.
+ */
+ tli = tliOfPointInHistory(tliRecPtr, 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) (tliRecPtr >> 32),
+ (uint32) tliRecPtr,
+ tli, curFileTLI);
+ }
+ curFileTLI = tli;
+ RequestXLogStreaming(tli, ptr, PrimaryConnInfo,
+ PrimarySlotName, wal_receiver_create_temp_slot);
+ receivedUpto = 0;
+ }
+
+ /*
+ * Check if WAL receiver is active or wait to start up.
*/
if (!WalRcvStreaming())
{
@@ -12241,6 +12269,50 @@ WaitForWALToBecomeAvailable(XLogRecPtr RecPtr, bool randAccess,
return false; /* not reached */
}
+/*
+ * Re-read config file and plan to restart running walreceiver if
+ * connection settings was changed.
+ */
+void
+ProcessStartupSigHup(void)
+{
+ char *conninfo = pstrdup(PrimaryConnInfo);
+ char *slotname = pstrdup(PrimarySlotName);
+ bool conninfoChanged;
+ bool slotnameChanged;
+
+ ProcessConfigFile(PGC_SIGHUP);
+
+ /*
+ * We need restart walreceiver if replication settings was changed.
+ */
+ conninfoChanged = (strcmp(conninfo, PrimaryConnInfo) != 0);
+ slotnameChanged = (strcmp(slotname, PrimarySlotName) != 0);
+
+ pfree(conninfo);
+ pfree(slotname);
+
+ if ((conninfoChanged || slotnameChanged) &&
+ currentSource == XLOG_FROM_STREAM
+ && WalRcvRunning())
+ {
+ if (conninfoChanged && strcmp(PrimaryConnInfo, "") == 0)
+ ereport(LOG,
+ (errmsg("The WAL receiver is going to be shut down due to change of %s",
+ "primary_conninfo")));
+ else if (conninfoChanged && slotnameChanged)
+ ereport(LOG,
+ (errmsg("The WAL receiver is going to be restarted due to change of %s and %s",
+ "primary_conninfo", "primary_slot_name")));
+ else
+ ereport(LOG,
+ (errmsg("The WAL receiver is going to be restarted due to change of %s",
+ conninfoChanged ? "primary_conninfo" : "primary_slot_name")));
+
+ pendingWalRcvRestart = true;
+ }
+}
+
/*
* Determine what log level should be used to report a corrupt WAL record
* in the current WAL page, previously read by XLogPageRead().
diff --git a/src/backend/postmaster/startup.c b/src/backend/postmaster/startup.c
index c2250d7d4e..c396fdae9a 100644
--- a/src/backend/postmaster/startup.c
+++ b/src/backend/postmaster/startup.c
@@ -101,12 +101,12 @@ void
HandleStartupProcInterrupts(void)
{
/*
- * Check if we were requested to re-read config file.
+ * Process any requests or signals received recently.
*/
if (got_SIGHUP)
{
got_SIGHUP = false;
- ProcessConfigFile(PGC_SIGHUP);
+ ProcessStartupSigHup();
}
/*
diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index 779d19f1c1..0fd9886458 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -671,7 +671,11 @@ WalRcvWaitForStartPosition(XLogRecPtr *startpoint, TimeLineID *startpointTLI)
walrcv->walRcvState == WALRCV_STOPPING);
if (walrcv->walRcvState == WALRCV_RESTARTING)
{
- /* we don't expect primary_conninfo to change */
+ /*
+ * We don't need handle changes of primary_conninfo or
+ * primary_slotname here. Startup process will shutdown running
+ * walreceiver in this case.
+ */
*startpoint = walrcv->receiveStart;
*startpointTLI = walrcv->receiveStartTLI;
walrcv->walRcvState = WALRCV_STREAMING;
diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index 80b6801c82..8d9bdc0eaf 100644
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -3697,7 +3697,7 @@ static struct config_string ConfigureNamesString[] =
},
{
- {"primary_conninfo", PGC_POSTMASTER, REPLICATION_STANDBY,
+ {"primary_conninfo", PGC_SIGHUP, REPLICATION_STANDBY,
gettext_noop("Sets the connection string to be used to connect to the sending server."),
NULL,
GUC_SUPERUSER_ONLY
@@ -3708,7 +3708,7 @@ static struct config_string ConfigureNamesString[] =
},
{
- {"primary_slot_name", PGC_POSTMASTER, REPLICATION_STANDBY,
+ {"primary_slot_name", PGC_SIGHUP, REPLICATION_STANDBY,
gettext_noop("Sets the name of the replication slot to use on the sending server."),
NULL
},
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index f2e55d1bd3..31096725fd 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -309,9 +309,7 @@
# These settings are ignored on a master server.
#primary_conninfo = '' # connection string to sending server
- # (change requires restart)
#primary_slot_name = '' # replication slot on sending server
- # (change requires restart)
#promote_trigger_file = '' # file name whose presence ends recovery
#hot_standby = on # "off" disallows queries during recovery
# (change requires restart)
diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h
index 12362421d7..94009eb7be 100644
--- a/src/include/access/xlog.h
+++ b/src/include/access/xlog.h
@@ -320,6 +320,7 @@ extern void SetWalWriterSleeping(bool sleeping);
extern void XLogRequestWalReceiverReply(void);
+extern void ProcessStartupSigHup(void);
extern void assign_max_wal_size(int newval, void *extra);
extern void assign_checkpoint_completion_target(double newval, void *extra);
diff --git a/src/test/recovery/t/001_stream_rep.pl b/src/test/recovery/t/001_stream_rep.pl
index d09ebe65a3..52585a1014 100644
--- a/src/test/recovery/t/001_stream_rep.pl
+++ b/src/test/recovery/t/001_stream_rep.pl
@@ -3,7 +3,7 @@ use strict;
use warnings;
use PostgresNode;
use TestLib;
-use Test::More tests => 34;
+use Test::More tests => 35;
# Initialize master node
my $node_master = get_new_node('master');
@@ -208,7 +208,9 @@ $node_standby_2->append_conf('postgresql.conf',
"primary_slot_name = $slotname_2");
$node_standby_2->append_conf('postgresql.conf',
"wal_receiver_status_interval = 1");
-$node_standby_2->restart;
+# should be able change primary_slot_name without restart
+# will wait effect in get_slot_xmins above
+$node_standby_2->reload;
# Fetch xmin columns from slot's pg_replication_slots row, after waiting for
# given boolean condition to be true to ensure we've reached a quiescent state
@@ -345,6 +347,24 @@ is($xmin, '', 'xmin of cascaded slot null with hs feedback reset');
is($catalog_xmin, '',
'catalog xmin of cascaded slot still null with hs_feedback reset');
+note "check change primary_conninfo without restart";
+$node_standby_2->append_conf('postgresql.conf',
+ "primary_slot_name = ''");
+$node_standby_2->enable_streaming($node_master);
+$node_standby_2->reload;
+
+# be sure do not streaming from cascade
+$node_standby_1->stop;
+
+my $newval = $node_master->safe_psql('postgres',
+'INSERT INTO replayed(val) SELECT coalesce(max(val),0) + 1 AS newval FROM replayed RETURNING val'
+);
+$node_master->wait_for_catchup($node_standby_2, 'replay',
+ $node_master->lsn('insert'));
+my $is_replayed = $node_standby_2->safe_psql('postgres',
+ qq[SELECT 1 FROM replayed WHERE val = $newval]);
+is($is_replayed, qq(1), "standby_2 didn't replay master value $newval");
+
# Test physical slot advancing and its durability. Create a new slot on
# the primary, not used by any of the standbys. This reserves WAL at creation.
my $phys_slot = 'phys_slot';
