From f2c829346fb9bc073052f65e56ebe6e4ec3ba756 Mon Sep 17 00:00:00 2001
From: Baji Shaik <shbaji@amazon.com>
Date: Wed, 11 Nov 2026 08:40:19 -0600
Subject: [PATCH v1 2/2] Add a test for the autovacuum freeze score wraparound

Hold an autovacuum worker at the autovacuum-worker-start injection
point, after it has read recentXid but before it scans pg_class, and
freeze a table meanwhile so that its relfrozenxid moves past the
worker's recentXid.  Without the previous commit, the worker computes
an xid score around 1e57 for the table.

Author: Baji Shaik <baji.pgdev@gmail.com>
---
 src/test/modules/test_misc/meson.build        |  1 +
 .../test_misc/t/016_autovacuum_score_wrap.pl  | 90 +++++++++++++++++++
 2 files changed, 91 insertions(+)
 create mode 100644 src/test/modules/test_misc/t/016_autovacuum_score_wrap.pl

diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build
index 5d81f5b13b..870124e25c 100644
--- a/src/test/modules/test_misc/meson.build
+++ b/src/test/modules/test_misc/meson.build
@@ -24,6 +24,7 @@ tests += {
       't/013_temp_obj_multisession.pl',
       't/014_log_statement_max_length.pl',
       't/015_temp_schema_exit_deferrable.pl',
+      't/016_autovacuum_score_wrap.pl',
     ],
     # The injection points are cluster-wide, so disable installcheck
     'runningcheck': false,
diff --git a/src/test/modules/test_misc/t/016_autovacuum_score_wrap.pl b/src/test/modules/test_misc/t/016_autovacuum_score_wrap.pl
new file mode 100644
index 0000000000..ef53d09ac7
--- /dev/null
+++ b/src/test/modules/test_misc/t/016_autovacuum_score_wrap.pl
@@ -0,0 +1,90 @@
+# Copyright (c) 2026, PostgreSQL Global Development Group
+
+# Test that an autovacuum worker's freeze score doesn't wrap around when a
+# table's relfrozenxid advances after the worker has read recentXid.
+#
+# The worker reads recentXid before do_autovacuum() scans pg_class.  This
+# test holds a worker at the autovacuum-worker-start injection point, which
+# is in that window, freezes a table so that its relfrozenxid moves past the
+# worker's recentXid, and then checks the xid score the worker computes for
+# the table.
+
+use strict;
+use warnings FATAL => 'all';
+use PostgreSQL::Test::Cluster;
+use PostgreSQL::Test::Utils;
+use Test::More;
+
+if ($ENV{enable_injection_points} ne 'yes')
+{
+	plan skip_all => 'Injection points not supported by this build';
+}
+
+my $node = PostgreSQL::Test::Cluster->new('node');
+$node->init;
+$node->append_conf(
+	'postgresql.conf', qq(
+autovacuum_naptime = 1
+log_min_messages = debug3
+));
+$node->start;
+
+if (!$node->check_extension('injection_points'))
+{
+	plan skip_all => 'Extension injection_points not installed';
+}
+
+$node->safe_psql(
+	'postgres', qq(
+    CREATE EXTENSION injection_points;
+    CREATE TABLE av_score_wrap (a int);
+    INSERT INTO av_score_wrap VALUES (1);
+));
+
+# From this point, autovacuum workers wait after reading recentXid.
+$node->safe_psql('postgres',
+	"SELECT injection_points_attach('autovacuum-worker-start', 'wait');");
+$node->reload();
+
+# Hold a worker for the postgres database.  Workers for other databases are
+# let go.
+my $av_pid;
+for (my $i = 0; $i < 30; $i++)
+{
+	$node->wait_for_event('autovacuum worker', 'autovacuum-worker-start');
+	$av_pid = $node->safe_psql(
+		'postgres', qq(
+        SELECT pid FROM pg_stat_activity
+         WHERE backend_type = 'autovacuum worker'
+           AND wait_event = 'autovacuum-worker-start'
+           AND datname = 'postgres'
+         LIMIT 1;
+    ));
+	last if $av_pid ne '';
+	$node->safe_psql('postgres',
+		"SELECT injection_points_wakeup('autovacuum-worker-start');");
+}
+isnt($av_pid, '', 'autovacuum worker for postgres held at injection point');
+
+# Move the table's relfrozenxid past the worker's recentXid.
+$node->safe_psql('postgres', "SELECT pg_current_xact_id();") for (1 .. 5);
+$node->safe_psql('postgres', 'VACUUM (FREEZE) av_score_wrap;');
+
+my $offset = -s $node->logfile;
+
+# Let the worker go on; it computes the scores in its pg_class scan.
+$node->safe_psql(
+	'postgres', qq(
+    SELECT injection_points_detach('autovacuum-worker-start');
+    SELECT injection_points_wakeup('autovacuum-worker-start');
+));
+
+$node->wait_for_log(qr/av_score_wrap: vac: .* xid score: /, $offset);
+
+my $log = slurp_file($node->logfile, $offset);
+my ($xid_score) = $log =~ /av_score_wrap: vac: .* xid score: ([0-9.e+]+)/;
+note "xid score for av_score_wrap: $xid_score";
+cmp_ok($xid_score, '<', 1.0,
+	'xid score of a just-frozen table does not wrap around');
+
+done_testing();
-- 
2.54.0 (Apple Git-157)