Subject: [PATCH v1 1/2] pg_upgrade: Test --check with a running source server

From: Bertrand Drouvot <[email-masked]>
Date: Mon, 31 Aug 2026 03:03:33 +0000

Commit 4fff78f009 added TAP coverage for pg_upgrade --check, but only after
stopping the source server. Add coverage with the source still running.

This covers live server detection, connection details from postmaster.pid,
control data from pg_controldata, reuse of the running postmaster, and the
requirement for different source and target ports.

Also test that logical slots with unconsumed WAL are accepted during a live
check. The existing offline check verifies that the same slots are rejected after
shutdown.

Author: Bertrand Drouvot <[email-masked]>
Reviewed-by:
Discussion: https://postgr.es/m/...
---
 src/bin/pg_upgrade/t/002_pg_upgrade.pl    | 45 ++++++++++++++++++++---
 src/bin/pg_upgrade/t/003_logical_slots.pl | 13 +++++++
 2 files changed, 53 insertions(+), 5 deletions(-)
 100.0% src/bin/pg_upgrade/t/

diff --git a/src/bin/pg_upgrade/t/002_pg_upgrade.pl b/src/bin/pg_upgrade/t/002_pg_upgrade.pl
index 0a4121fdc4d..9b904a8d1ea 100644
--- a/src/bin/pg_upgrade/t/002_pg_upgrade.pl
+++ b/src/bin/pg_upgrade/t/002_pg_upgrade.pl
@@ -475,6 +475,46 @@ if (defined($ENV{oldinstall}))
 	}
 }
 
+# In a VPATH build, we'll be started in the source directory, but we want
+# to run pg_upgrade in the build directory so that any files generated finish
+# in it, like delete_old_cluster.{sh,bat}.
+chdir ${PostgreSQL::Test::Utils::tmp_check};
+
+my @live_check_command = (
+	'pg_upgrade', '--no-sync',
+	'--old-datadir' => $oldnode->data_dir,
+	'--new-datadir' => $newnode->data_dir,
+	'--old-bindir' => $oldbindir,
+	'--new-bindir' => $newbindir,
+	'--socketdir' => $newnode->host,
+	'--old-port' => $oldnode->port);
+
+# A live check must use different ports for the running old server and
+# the temporary new server.
+command_checks_all(
+	[
+		@live_check_command,
+		'--new-port' => $oldnode->port,
+		$mode, '--check',
+	],
+	1,
+	[
+		qr/When checking a live server, the old and new port numbers must be different\./
+	],
+	[],
+	'pg_upgrade --check with the same old and new ports');
+
+rmtree($newnode->data_dir . "/pg_upgrade_output.d");
+
+# Check the old cluster while it is running.
+command_ok(
+	[
+		@live_check_command,
+		'--new-port' => $newnode->port,
+		$mode, '--check',
+	],
+	'run of pg_upgrade --check with old instance running');
+
 # Create an invalid database, will be deleted below
 $oldnode->safe_psql(
 	'postgres', qq(
@@ -482,11 +522,6 @@ $oldnode->safe_psql(
   UPDATE pg_database SET datconnlimit = -2 WHERE datname = 'regression_invalid';
 ));
 
-# In a VPATH build, we'll be started in the source directory, but we want
-# to run pg_upgrade in the build directory so that any files generated finish
-# in it, like delete_old_cluster.{sh,bat}.
-chdir ${PostgreSQL::Test::Utils::tmp_check};
-
 # Upgrade the instance.
 $oldnode->stop;
 
diff --git a/src/bin/pg_upgrade/t/003_logical_slots.pl b/src/bin/pg_upgrade/t/003_logical_slots.pl
index 01ab82402ae..b0ebf845747 100644
--- a/src/bin/pg_upgrade/t/003_logical_slots.pl
+++ b/src/bin/pg_upgrade/t/003_logical_slots.pl
@@ -158,6 +158,19 @@ $oldpub->safe_psql(
 		SELECT count(*) FROM pg_logical_emit_message('false', 'prefix', 'This is a non-transactional message', true);
 		SELECT pg_replication_slot_advance('test_slot3', pg_current_wal_lsn());
 ]);
+
+# Sleep here because Windows builds cannot check postmaster.pid exactly,
+# so they may mistake a pre-existing postmaster.pid for one created by the
+# postmaster they start. Waiting more than the 2 seconds slop time allowed
+# by wait_for_postmaster_start() prevents that mistake.
+sleep 3 if ($windows_os);
+
+# A live check cannot require slots to have consumed all WAL because the old
+# server can generate more WAL concurrently. Verify that these slots are accepted
+# now. The check below verifies rejection after shutdown.
+command_ok([ @pg_upgrade_cmd, '--check' ],
+	'pg_upgrade --check with live old cluster and unconsumed WAL');
+
 $oldpub->stop;
 
 # pg_upgrade will fail because there are slots still having unconsumed WAL
-- 
2.34.1

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