From 9a7b7adc130a197e5c993a99e6aaa981f9341a35 Mon Sep 17 00:00:00 2001
From: Michael Paquier <michael@paquier.xyz>
Date: Thu, 12 Jul 2018 10:19:35 +0900
Subject: [PATCH] Make logical WAL sender report streaming state appropriately
WAL senders sending logically-decoded data fail to properly report in
"streaming" state when starting up, hence as long as one extra record is
not replayed, such WAL senders would remain in a "catchup" state, which
is inconsistent with the physical cousin.
This can be easily reproduced by for example using pg_recvlogical and
restarting the upstream server. The TAP tests have been slightly
modified to detect the failure and strengthened so as future tests also
make sure that a node is in streaming state when waiting for its
catchup.
Backpatch down to 9.4 where this code has been introduced.
Reported-by: Sawada Masahiko
Author: Simon Riggs, Sawada Masahiko
Reviewed-by: Petr Jelinek, Michael Paquier, Vaishnavi Prabakaran
Discussion: https://postgr.es/m/CAD21AoB2ZbCCqOx=bgKMcLrAvs1V0ZMqzs7wBTuDySezTGtMZA@mail.gmail.com
---
src/backend/replication/walsender.c | 20 +++++++++++++++-----
src/test/perl/PostgresNode.pm | 5 +++--
src/test/subscription/t/001_rep_changes.pl | 5 +++++
3 files changed, 23 insertions(+), 7 deletions(-)
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index e47ddca6bca..3a0106bc933 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -2169,7 +2169,7 @@ WalSndLoop(WalSndSendDataCallback send_data)
if (MyWalSnd->state == WALSNDSTATE_CATCHUP)
{
ereport(DEBUG1,
- (errmsg("standby \"%s\" has now caught up with primary",
+ (errmsg("\"%s\" has now caught up with upstream server",
application_name)));
WalSndSetState(WALSNDSTATE_STREAMING);
}
@@ -2758,10 +2758,10 @@ XLogSendLogical(void)
char *errm;
/*
- * Don't know whether we've caught up yet. We'll set it to true in
- * WalSndWaitForWal, if we're actually waiting. We also set to true if
- * XLogReadRecord() had to stop reading but WalSndWaitForWal didn't wait -
- * i.e. when we're shutting down.
+ * Don't know whether we've caught up yet. We'll set WalSndCaughtUp to
+ * true in WalSndWaitForWal, if we're actually waiting. We also set to
+ * true if XLogReadRecord() had to stop reading but WalSndWaitForWal
+ * didn't wait - i.e. when we're shutting down.
*/
WalSndCaughtUp = false;
@@ -2774,6 +2774,9 @@ XLogSendLogical(void)
if (record != NULL)
{
+ /* XXX: Note that logical decoding cannot be used while in recovery */
+ XLogRecPtr flushPtr = GetFlushRecPtr();
+
/*
* Note the lack of any call to LagTrackerWrite() which is handled by
* WalSndUpdateProgress which is called by output plugin through
@@ -2782,6 +2785,13 @@ XLogSendLogical(void)
LogicalDecodingProcessRecord(logical_decoding_ctx, logical_decoding_ctx->reader);
sentPtr = logical_decoding_ctx->reader->EndRecPtr;
+
+ /*
+ * If we have sent a record that is at or beyond the flushed point, we
+ * have caught up.
+ */
+ if (sentPtr >= flushPtr)
+ WalSndCaughtUp = true;
}
else
{
diff --git a/src/test/perl/PostgresNode.pm b/src/test/perl/PostgresNode.pm
index a08af65695b..79fb4570758 100644
--- a/src/test/perl/PostgresNode.pm
+++ b/src/test/perl/PostgresNode.pm
@@ -1535,7 +1535,8 @@ also works for logical subscriptions)
until its replication location in pg_stat_replication equals or passes the
upstream's WAL insert point at the time this function is called. By default
the replay_lsn is waited for, but 'mode' may be specified to wait for any of
-sent|write|flush|replay.
+sent|write|flush|replay. The connection catching up must be in a streaming
+state.
If there is no active replication connection from this peer, waits until
poll_query_until timeout.
@@ -1580,7 +1581,7 @@ sub wait_for_catchup
. $lsn_expr . " on "
. $self->name . "\n";
my $query =
- qq[SELECT $lsn_expr <= ${mode}_lsn FROM pg_catalog.pg_stat_replication WHERE application_name = '$standby_name';];
+ qq[SELECT $lsn_expr <= ${mode}_lsn AND state = 'streaming' FROM pg_catalog.pg_stat_replication WHERE application_name = '$standby_name';];
$self->poll_query_until('postgres', $query)
or croak "timed out waiting for catchup";
print "done\n";
diff --git a/src/test/subscription/t/001_rep_changes.pl b/src/test/subscription/t/001_rep_changes.pl
index 503556fd6cd..d94458e00e1 100644
--- a/src/test/subscription/t/001_rep_changes.pl
+++ b/src/test/subscription/t/001_rep_changes.pl
@@ -188,6 +188,11 @@ $node_publisher->safe_psql('postgres',
"INSERT INTO tab_ins SELECT generate_series(1001,1100)");
$node_publisher->safe_psql('postgres', "DELETE FROM tab_rep");
+# Restart the publisher and check the state of the subscriber which
+# should be in a streaming state after catching up.
+$node_publisher->stop('fast');
+$node_publisher->start;
+
$node_publisher->wait_for_catchup($appname);
$result = $node_subscriber->safe_psql('postgres',