On 2020-Mar-27, Alvaro Herrera wrote:
> I pushed the wal_receiver_create_temp_slot bugfix, because I realized
> after looking for long enough at WalReceiverMain() that the code was
> beyond saving. I'll be pushing the rest of this later today.
So here's the next one. I still have to go over the doc changes here,
but at least the tests are passing for me.
I think I should set aside your new draft for now, but I think we should
still get it in pg13 to avoid having the change the semantics of the
walreceiver temp slot in the next release.
--
Álvaro Herrera https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index b5de6c3237..c5160fe907 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4028,9 +4028,15 @@ 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">
@@ -4045,9 +4051,13 @@ 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>
@@ -4163,7 +4173,11 @@ 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 off. This parameter can only be set at server start.
+ The default is off. This parameter can only be set in the
+ <filename>postgresql.conf</filename> file or on the server command line.
+ </para>
+ <para>
+ The WAL receiver is restarted after an update of <varname>wal_receiver_create_temp_slot</varname>.
</para>
</listitem>
</varlistentry>
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index c7d93d3735..d3a299ba4c 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -816,9 +816,13 @@ static XLogSource readSource = XLOG_FROM_ANY;
* currently have a WAL file open. If lastSourceFailed is set, our last
* attempt to read from currentSource failed, and we should try another source
* next.
+ *
+ * pendingWalRcvRestart is set when a config change occurs that requires a
+ * walreceiver restart. This is only valid in XLOG_FROM_STREAM state.
*/
static XLogSource currentSource = XLOG_FROM_ANY;
static bool lastSourceFailed = false;
+static bool pendingWalRcvRestart = false;
typedef struct XLogPageReadPrivate
{
@@ -11905,6 +11909,7 @@ WaitForWALToBecomeAvailable(XLogRecPtr RecPtr, bool randAccess,
for (;;)
{
XLogSource oldSource = currentSource;
+ bool startWalReceiver = false;
/*
* First check if we failed to read from the current source, and
@@ -11939,54 +11944,11 @@ WaitForWALToBecomeAvailable(XLogRecPtr RecPtr, bool randAccess,
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.
+ * Move to XLOG_FROM_STREAM state, and set to start a
+ * walreceiver if necessary.
*/
currentSource = XLOG_FROM_STREAM;
+ startWalReceiver = true;
break;
case XLOG_FROM_STREAM:
@@ -12138,7 +12100,71 @@ WaitForWALToBecomeAvailable(XLogRecPtr RecPtr, bool randAccess,
Assert(StandbyMode);
/*
- * Check if WAL receiver is still active.
+ * First, shutdown walreceiver if its restart has been
+ * requested -- but no point if we're already slated for
+ * starting it.
+ */
+ if (pendingWalRcvRestart && !startWalReceiver)
+ {
+ 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())
{
@@ -12266,6 +12292,18 @@ WaitForWALToBecomeAvailable(XLogRecPtr RecPtr, bool randAccess,
return false; /* not reached */
}
+void
+StartupRequestWalReceiverRestart(void)
+{
+ if (currentSource == XLOG_FROM_STREAM && WalRcvRunning())
+ {
+ ereport(LOG,
+ (errmsg("wal receiver process shutdown requested")));
+
+ 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/access/transam/xlogreader.c b/src/backend/access/transam/xlogreader.c
index 32f02256ed..f3fea5132f 100644
--- a/src/backend/access/transam/xlogreader.c
+++ b/src/backend/access/transam/xlogreader.c
@@ -585,9 +585,9 @@ ReadPageInternal(XLogReaderState *state, XLogRecPtr pageptr, int reqLen)
/*
* Data is not in our buffer.
*
- * Every time we actually read the page, even if we looked at parts of it
- * before, we need to do verification as the read_page callback might now
- * be rereading data from a different source.
+ * Every time we actually read the segment, even if we looked at parts of
+ * it before, we need to do verification as the read_page callback might
+ * now be rereading data from a different source.
*
* Whenever switching to a new WAL segment, we read the first page of the
* file and validate its header, even if that's not where the target
diff --git a/src/backend/postmaster/startup.c b/src/backend/postmaster/startup.c
index 8952676765..fd9ac35dac 100644
--- a/src/backend/postmaster/startup.c
+++ b/src/backend/postmaster/startup.c
@@ -96,17 +96,51 @@ StartupProcShutdownHandler(SIGNAL_ARGS)
errno = save_errno;
}
+/*
+ * Re-read the config file.
+ *
+ * If one of the critical walreceiver options has changed, flag xlog.c
+ * to restart it.
+ */
+static void
+StartupRereadConfig(void)
+{
+ char *conninfo = pstrdup(PrimaryConnInfo);
+ char *slotname = pstrdup(PrimarySlotName);
+ bool tempSlot = wal_receiver_create_temp_slot;
+ bool conninfoChanged;
+ bool slotnameChanged;
+ bool tempSlotChanged = false;
+
+ ProcessConfigFile(PGC_SIGHUP);
+
+ conninfoChanged = strcmp(conninfo, PrimaryConnInfo) != 0;
+ slotnameChanged = strcmp(slotname, PrimarySlotName) != 0;
+
+ /*
+ * wal_receiver_create_temp_slot is used only when we have no slot
+ * configured. We do not need to track this change if it has no effect.
+ */
+ if (!slotnameChanged && strcmp(PrimarySlotName, "") == 0)
+ tempSlotChanged = tempSlot != wal_receiver_create_temp_slot;
+ pfree(conninfo);
+ pfree(slotname);
+
+ if (conninfoChanged || slotnameChanged || tempSlotChanged)
+ StartupRequestWalReceiverRestart();
+}
+
/* Handle various signals that might be sent to the startup process */
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);
+ StartupRereadConfig();
}
/*
diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a1459ca7f6..fad20986db 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -679,7 +679,11 @@ WalRcvWaitForStartPosition(XLogRecPtr *startpoint, TimeLineID *startpointTLI)
walrcv->walRcvState == WALRCV_STOPPING);
if (walrcv->walRcvState == WALRCV_RESTARTING)
{
- /* we don't expect primary_conninfo to change */
+ /*
+ * No need to handle changes in primary_conninfo or
+ * primary_slotname here. Startup process will signal us in case
+ * those change.
+ */
*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 2c3cbbaa68..53665971f5 100644
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -2050,7 +2050,7 @@ static struct config_bool ConfigureNamesBool[] =
},
{
- {"wal_receiver_create_temp_slot", PGC_POSTMASTER, REPLICATION_STANDBY,
+ {"wal_receiver_create_temp_slot", PGC_SIGHUP, 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,
@@ -3717,7 +3717,7 @@ 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
@@ -3728,7 +3728,7 @@ 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..f01e43b818 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)
@@ -323,7 +321,6 @@
# -1 allows indefinite delay
#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/src/include/access/xlog.h b/src/include/access/xlog.h
index a4485efc00..2b1b67d35c 100644
--- a/src/include/access/xlog.h
+++ b/src/include/access/xlog.h
@@ -319,6 +319,7 @@ extern bool CheckPromoteSignal(void);
extern void WakeupRecovery(void);
extern void SetWalWriterSleeping(bool sleeping);
+extern void StartupRequestWalReceiverRestart(void);
extern void XLogRequestWalReceiverReply(void);
extern void assign_max_wal_size(int 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';
