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Add pg_rewind, for re-synchronizing a master server after failback.
Earlier versions of this tool were available (and still are) on github. Thanks to Michael Paquier, Alvaro Herrera, Peter Eisentraut, Amit Kapila, and Satoshi Nagayasu for review.
This commit is contained in:
Heikki Linnakangas
271
src/bin/pg_rewind/RewindTest.pm
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271
src/bin/pg_rewind/RewindTest.pm
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package RewindTest;
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# Test driver for pg_rewind. Each test consists of a cycle where a new cluster
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# is first created with initdb, and a streaming replication standby is set up
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# to follow the master. Then the master is shut down and the standby is
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# promoted, and finally pg_rewind is used to rewind the old master, using the
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# standby as the source.
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#
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# To run a test, the test script (in t/ subdirectory) calls the functions
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# in this module. These functions should be called in this sequence:
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#
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# 1. init_rewind_test - sets up log file etc.
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#
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# 2. setup_cluster - creates a PostgreSQL cluster that runs as the master
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#
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# 3. create_standby - runs pg_basebackup to initialize a standby server, and
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# sets it up to follow the master.
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#
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# 4. promote_standby - runs "pg_ctl promote" to promote the standby server.
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# The old master keeps running.
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#
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# 5. run_pg_rewind - stops the old master (if it's still running) and runs
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# pg_rewind to synchronize it with the now-promoted standby server.
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#
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# The test script can use the helper functions master_psql and standby_psql
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# to run psql against the master and standby servers, respectively. The
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# test script can also use the $connstr_master and $connstr_standby global
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# variables, which contain libpq connection strings for connecting to the
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# master and standby servers. The data directories are also available
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# in paths $test_master_datadir and $test_standby_datadir
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use TestLib;
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use Test::More;
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use File::Copy;
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use File::Path qw(remove_tree);
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use IPC::Run qw(run start);
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use Exporter 'import';
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our @EXPORT = qw(
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$connstr_master
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$connstr_standby
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$test_master_datadir
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$test_standby_datadir
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append_to_file
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master_psql
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standby_psql
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check_query
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init_rewind_test
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setup_cluster
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create_standby
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promote_standby
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run_pg_rewind
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);
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# Adjust these paths for your environment
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my $testroot = "./tmp_check";
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$test_master_datadir="$testroot/data_master";
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$test_standby_datadir="$testroot/data_standby";
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mkdir $testroot;
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# Log files are created here
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mkdir "regress_log";
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# Define non-conflicting ports for both nodes.
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my $port_master=$ENV{PGPORT};
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my $port_standby=$port_master + 1;
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my $log_path;
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my $tempdir_short;
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$connstr_master="port=$port_master";
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$connstr_standby="port=$port_standby";
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$ENV{PGDATABASE} = "postgres";
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sub master_psql
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{
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my $cmd = shift;
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system_or_bail("psql -q --no-psqlrc -d $connstr_master -c \"$cmd\"");
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}
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sub standby_psql
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{
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my $cmd = shift;
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system_or_bail("psql -q --no-psqlrc -d $connstr_standby -c \"$cmd\"");
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}
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# Run a query against the master, and check that the output matches what's
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# expected
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sub check_query
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{
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my ($query, $expected_stdout, $test_name) = @_;
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my ($stdout, $stderr);
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# we want just the output, no formatting
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my $result = run ['psql', '-q', '-A', '-t', '--no-psqlrc',
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'-d', $connstr_master,
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'-c' , $query],
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'>', \$stdout, '2>', \$stderr;
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# We don't use ok() for the exit code and stderr, because we want this
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# check to be just a single test.
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if (!$result) {
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fail ("$test_name: psql exit code");
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} elsif ($stderr ne '') {
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diag $stderr;
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fail ("$test_name: psql no stderr");
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} else {
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is ($stdout, $expected_stdout, "$test_name: query result matches");
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}
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}
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sub append_to_file
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{
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my($filename, $str) = @_;
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open my $fh, ">>", $filename or die "could not open file $filename";
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print $fh $str;
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close $fh;
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}
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sub init_rewind_test
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{
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($testname, $test_mode) = @_;
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$log_path="regress_log/pg_rewind_log_${testname}_${test_mode}";
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remove_tree $log_path;
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}
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sub setup_cluster
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{
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$tempdir_short = tempdir_short;
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# Initialize master, data checksums are mandatory
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remove_tree($test_master_datadir);
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standard_initdb($test_master_datadir);
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# Custom parameters for master's postgresql.conf
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append_to_file("$test_master_datadir/postgresql.conf", qq(
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wal_level = hot_standby
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max_wal_senders = 2
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wal_keep_segments = 20
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max_wal_size = 200MB
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shared_buffers = 1MB
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wal_log_hints = on
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hot_standby = on
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autovacuum = off
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max_connections = 10
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));
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# Accept replication connections on master
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append_to_file("$test_master_datadir/pg_hba.conf", qq(
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local replication all trust
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));
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system_or_bail("pg_ctl -w -D $test_master_datadir -o \"-k $tempdir_short --listen-addresses='' -p $port_master\" start >>$log_path 2>&1");
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#### Now run the test-specific parts to initialize the master before setting
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# up standby
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$ENV{PGHOST} = $tempdir_short;
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}
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sub create_standby
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{
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# Set up standby with necessary parameter
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remove_tree $test_standby_datadir;
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# Base backup is taken with xlog files included
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system_or_bail("pg_basebackup -D $test_standby_datadir -p $port_master -x >>$log_path 2>&1");
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append_to_file("$test_standby_datadir/recovery.conf", qq(
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primary_conninfo='$connstr_master'
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standby_mode=on
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recovery_target_timeline='latest'
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));
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# Start standby
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system_or_bail("pg_ctl -w -D $test_standby_datadir -o \"-k $tempdir_short --listen-addresses='' -p $port_standby\" start >>$log_path 2>&1");
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# sleep a bit to make sure the standby has caught up.
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sleep 1;
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}
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sub promote_standby
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{
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#### Now run the test-specific parts to run after standby has been started
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# up standby
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# Now promote slave and insert some new data on master, this will put
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# the master out-of-sync with the standby.
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system_or_bail("pg_ctl -w -D $test_standby_datadir promote >>$log_path 2>&1");
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sleep 1;
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}
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sub run_pg_rewind
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{
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# Stop the master and be ready to perform the rewind
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system_or_bail("pg_ctl -w -D $test_master_datadir stop -m fast >>$log_path 2>&1");
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# At this point, the rewind processing is ready to run.
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# We now have a very simple scenario with a few diverged WAL record.
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# The real testing begins really now with a bifurcation of the possible
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# scenarios that pg_rewind supports.
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# Keep a temporary postgresql.conf for master node or it would be
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# overwritten during the rewind.
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copy("$test_master_datadir/postgresql.conf", "$testroot/master-postgresql.conf.tmp");
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# Now run pg_rewind
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if ($test_mode == "local")
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{
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# Do rewind using a local pgdata as source
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# Stop the master and be ready to perform the rewind
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system_or_bail("pg_ctl -w -D $test_standby_datadir stop -m fast >>$log_path 2>&1");
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my $result =
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run(['./pg_rewind',
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"--debug",
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"--source-pgdata=$test_standby_datadir",
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"--target-pgdata=$test_master_datadir"],
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'>>', $log_path, '2>&1');
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ok ($result, 'pg_rewind local');
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}
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elsif ($test_mode == "remote")
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{
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# Do rewind using a remote connection as source
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my $result =
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run(['./pg_rewind',
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"--source-server=\"port=$port_standby dbname=postgres\"",
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"--target-pgdata=$test_master_datadir"],
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'>>', $log_path, '2>&1');
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ok ($result, 'pg_rewind remote');
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} else {
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# Cannot come here normally
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die("Incorrect test mode specified");
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}
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# Now move back postgresql.conf with old settings
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move("$testroot/master-postgresql.conf.tmp", "$test_master_datadir/postgresql.conf");
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# Plug-in rewound node to the now-promoted standby node
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append_to_file("$test_master_datadir/recovery.conf", qq(
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primary_conninfo='port=$port_standby'
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standby_mode=on
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recovery_target_timeline='latest'
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));
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# Restart the master to check that rewind went correctly
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system_or_bail("pg_ctl -w -D $test_master_datadir -o \"-k $tempdir_short --listen-addresses='' -p $port_master\" start >>$log_path 2>&1");
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#### Now run the test-specific parts to check the result
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}
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# Clean up after the test. Stop both servers, if they're still running.
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END
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{
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my $save_rc = $?;
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if ($test_master_datadir)
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{
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system "pg_ctl -D $test_master_datadir -s -m immediate stop 2> /dev/null";
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}
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if ($test_standby_datadir)
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{
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system "pg_ctl -D $test_standby_datadir -s -m immediate stop 2> /dev/null";
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}
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$? = $save_rc;
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}
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