Fix incremental backup interaction with XLOG_DBASE_CREATE_FILE_COPY.

After XLOG_DBASE_CREATE_FILE_COPY, a correct incremental backup needs
to copy in full everything with the database and tablespace OID
mentioned in that record; but that record doesn't specifically mention
the blocks, or even the relfilenumbers, of the affected relations.
As a result, we were failing to copy data that we should have copied.

To fix, enter the DB OID and tablespace OID into the block reference
table with relfilenumber 0 and limit block 0; and treat that as a
limit block of 0 for every relfilenumber whose DB OID and tablespace
OID match.

Also, add a test case.

Patch by me, reviewed by Noah Misch.

Discussion: http://postgr.es/m/CA+Tgmob0xa=ByvGLMdAgkUZyVQE=r4nyYZ_VEa40FCfEDFnTKA@mail.gmail.com

2 files changed, 59 insertions, 0 deletions

diff --git a/src/bin/pg_combinebackup/meson.build b/src/bin/pg_combinebackup/meson.build
index 30dbbaa6cfa..1d4b9c218fd 100644
--- a/src/bin/pg_combinebackup/meson.build
+++ b/src/bin/pg_combinebackup/meson.build
@@ -33,6 +33,7 @@ tests += {
       't/003_timeline.pl',
       't/004_manifest.pl',
       't/005_integrity.pl',
+      't/006_db_file_copy.pl',
     ],
   }
 }
diff --git a/src/bin/pg_combinebackup/t/006_db_file_copy.pl b/src/bin/pg_combinebackup/t/006_db_file_copy.pl
new file mode 100644
index 00000000000..24f55449c63
--- /dev/null
+++ b/src/bin/pg_combinebackup/t/006_db_file_copy.pl
@@ -0,0 +1,58 @@
+# Copyright (c) 2021-2024, PostgreSQL Global Development Group
+
+use strict;
+use warnings FATAL => 'all';
+use File::Compare;
+use PostgreSQL::Test::Cluster;
+use PostgreSQL::Test::Utils;
+use Test::More;
+
+# Set up a new database instance.
+my $primary = PostgreSQL::Test::Cluster->new('primary');
+$primary->init(has_archiving => 1, allows_streaming => 1);
+$primary->append_conf('postgresql.conf', 'summarize_wal = on');
+$primary->start;
+
+# Initial setup.
+$primary->safe_psql('postgres', <<EOM);
+CREATE DATABASE lakh OID = 100000 STRATEGY = FILE_COPY
+EOM
+$primary->safe_psql('lakh', <<EOM);
+CREATE TABLE t1 (a int)
+EOM
+
+# Take a full backup.
+my $backup1path = $primary->backup_dir . '/backup1';
+$primary->command_ok(
+	[ 'pg_basebackup', '-D', $backup1path, '--no-sync', '-cfast' ],
+	"full backup");
+
+# Now make some database changes.
+$primary->safe_psql('postgres', <<EOM);
+DROP DATABASE lakh;
+CREATE DATABASE lakh OID = 100000 STRATEGY = FILE_COPY
+EOM
+
+# Take an incremental backup.
+my $backup2path = $primary->backup_dir . '/backup2';
+$primary->command_ok(
+	[ 'pg_basebackup', '-D', $backup2path, '--no-sync', '-cfast',
+	  '--incremental', $backup1path . '/backup_manifest' ],
+	"incremental backup");
+
+# Recover the incremental backup.
+my $restore = PostgreSQL::Test::Cluster->new('restore');
+$restore->init_from_backup($primary, 'backup2',
+						   combine_with_prior => [ 'backup1' ]);
+$restore->start();
+
+# Query the DB.
+my $stdout;
+my $stderr;
+$restore->psql('lakh', 'SELECT * FROM t1',
+			   stdout => \$stdout, stderr => \$stderr);
+is($stdout, '', 'SELECT * FROM t1: no stdout');
+like($stderr, qr/relation "t1" does not exist/,
+	 'SELECT * FROM t1: stderr missing table');
+
+done_testing();