From 83c958170b6f680e969be665c4f6fc410de5c63d Mon Sep 17 00:00:00 2001
From: Sehrope Sarkuni <sehrope@jackdb.com>
Date: Tue, 1 Sep 2026 11:43:09 +0000
Subject: [PATCH v3 2/3] Bound pg_waldump TAP test decodes to the records under
 test

The filter tests cannot match anything past the workload generated for
them, and three of them cannot match anything past the t1 and t2
records.  Capture an LSN at each boundary and stop reading there.  The
fall-off-the-end checks start at the contrecord LSN because they only
exercise the WAL tail.
---
 src/bin/pg_waldump/t/001_basic.pl | 42 +++++++++++++++++++++++--------
 1 file changed, 31 insertions(+), 11 deletions(-)

diff --git a/src/bin/pg_waldump/t/001_basic.pl b/src/bin/pg_waldump/t/001_basic.pl
index 9d846d2fe42..987bc015369 100644
--- a/src/bin/pg_waldump/t/001_basic.pl
+++ b/src/bin/pg_waldump/t/001_basic.pl
@@ -140,7 +140,16 @@ ROLLBACK;
 CREATE UNLOGGED TABLE t2 (x int);
 CREATE INDEX i2 ON t2 USING btree (x);
 INSERT INTO t2 SELECT generate_series(1, 10);
+});
+
+# Everything the --relation, --block and --fork tests can match lies
+# before this point.  The TRUNCATE changed the relfilenodes of t1 and
+# i1a, and only t2 and i2 have init forks.
+my $rel_test_end_lsn =
+  $node->safe_psql('postgres', 'SELECT pg_current_wal_insert_lsn()');
 
+$node->safe_psql(
+	'postgres', q{
 -- gin
 CREATE TABLE gin_idx_tbl (id bigserial PRIMARY KEY, data jsonb);
 CREATE INDEX gin_idx ON gin_idx_tbl USING gin (data);
@@ -185,6 +194,11 @@ CREATE TABLESPACE ts1 LOCATION '$tblspc_path';
 DROP TABLESPACE ts1;
 });
 
+# The option and filter tests read up to here.  The WAL beyond this
+# point only sets up the contrecord case.
+my $test_end_lsn =
+  $node->safe_psql('postgres', 'SELECT pg_current_wal_insert_lsn()');
+
 # Test: Decode a continuation record (contrecord) that spans multiple WAL
 # segments.
 #
@@ -438,11 +452,13 @@ for my $scenario (@scenarios)
 			],
 			qr/./,
 			'runs with path option and start and end locations');
+		# The two tests below only need the end of the WAL.  Starting at
+		# contrecord_lsn skips the bulk of the filler.
 		command_fails_like(
 			[
 				'pg_waldump',
 				'--path' => $path,
-				'--start' => $start_lsn,
+				'--start' => $contrecord_lsn,
 			],
 			qr/error: error in WAL record at/,
 			'falling off the end of the WAL results in an error');
@@ -451,7 +467,7 @@ for my $scenario (@scenarios)
 			[
 				'pg_waldump', '--quiet',
 				'--path' => $path,
-				'--start' => $start_lsn
+				'--start' => $contrecord_lsn
 			],
 			qr/error: error in WAL record at/,
 			'errors are shown with --quiet');
@@ -469,27 +485,31 @@ for my $scenario (@scenarios)
 		@lines = test_pg_waldump($path, $start_lsn, $end_lsn, '--limit' => 6);
 		is(@lines, 6, 'limit option observed');
 
-		@lines = test_pg_waldump($path, $start_lsn, $end_lsn, '--fullpage');
+		# The filter tests read up to test_end_lsn, checking every
+		# matching record while skipping the filler.
+		@lines =
+		  test_pg_waldump($path, $start_lsn, $test_end_lsn, '--fullpage');
 		is(grep(!/^rmgr:.*\bFPW\b/, @lines), 0, 'all output lines are FPW');
 
-		@lines = test_pg_waldump($path, $start_lsn, $end_lsn, '--stats');
+		@lines = test_pg_waldump($path, $start_lsn, $test_end_lsn, '--stats');
 		like($lines[0], qr/WAL statistics/, "statistics on stdout");
 		is(grep(/^rmgr:/, @lines), 0, 'no rmgr lines output');
 
 		@lines =
-		  test_pg_waldump($path, $start_lsn, $end_lsn, '--stats=record');
+		  test_pg_waldump($path, $start_lsn, $test_end_lsn, '--stats=record');
 		like($lines[0], qr/WAL statistics/, "statistics on stdout");
 		is(grep(/^rmgr:/, @lines), 0, 'no rmgr lines output');
 
-		@lines =
-		  test_pg_waldump($path, $start_lsn, $end_lsn, '--rmgr' => 'Btree');
+		@lines = test_pg_waldump($path, $start_lsn, $test_end_lsn,
+			'--rmgr' => 'Btree');
 		is(grep(!/^rmgr: Btree/, @lines), 0, 'only Btree lines');
 
-		@lines =
-		  test_pg_waldump($path, $start_lsn, $end_lsn, '--fork' => 'init');
+		# These three can only match records before rel_test_end_lsn.
+		@lines = test_pg_waldump($path, $start_lsn, $rel_test_end_lsn,
+			'--fork' => 'init');
 		is(grep(!/fork init/, @lines), 0, 'only init fork lines');
 
-		@lines = test_pg_waldump($path, $start_lsn, $end_lsn,
+		@lines = test_pg_waldump($path, $start_lsn, $rel_test_end_lsn,
 			'--relation' => "$default_ts_oid/$postgres_db_oid/$rel_t1_oid");
 		is( grep(!/rel $default_ts_oid\/$postgres_db_oid\/$rel_t1_oid/,
 				@lines),
@@ -497,7 +517,7 @@ for my $scenario (@scenarios)
 			'only lines for selected relation');
 
 		@lines = test_pg_waldump(
-			$path, $start_lsn, $end_lsn,
+			$path, $start_lsn, $rel_test_end_lsn,
 			'--relation' => "$default_ts_oid/$postgres_db_oid/$rel_i1a_oid",
 			'--block' => 1);
 		is(grep(!/\bblk 1\b/, @lines), 0, 'only lines for selected block');
-- 
2.43.0