PT-139 Added replication channels suport to pt-table-sync

bin/pt-archiver

@@ -3863,12 +3863,31 @@ sub get_slave_status {
             ||= $dbh->prepare('SHOW SLAVE STATUS');
       PTDEBUG && _d($dbh, 'SHOW SLAVE STATUS');
       $sth->execute();
-      my ($ss) = @{$sth->fetchall_arrayref({})};
+      my ($sss_rows) = $sth->fetchall_arrayref({}); # Show Slave Status rows
+
+      my $ss;
+      if ( $sss_rows && @$sss_rows ) {
+          if (scalar @$sss_rows > 1) {
+              if (!$self->{channel}) {
+                  warn 'This server returned more than one row for SHOW SLAVE STATUS but "channel" was not specified on the command line';
+                  return undef;
+              }
+              for my $row (@$sss_rows) {
+                  $row = { map { lc($_) => $row->{$_} } keys %$row }; # lowercase the keys
+                  if ($row->{channel_name} eq $self->{channel}) {
+                      $ss = $row;
+                      last;
+                  }
+              }
+          } else {
+              $ss = $sss_rows->[0];
+          }
 
           if ( $ss && %$ss ) {
              $ss = { map { lc($_) => $ss->{$_} } keys %$ss }; # lowercase the keys
              return $ss;
           }
+      }
 
       PTDEBUG && _d('This server returns nothing for SHOW SLAVE STATUS');
       $self->{not_a_slave}->{$dbh}++;
@@ -3912,8 +3931,9 @@ sub wait_for_master {
    my $result;
    my $waited;
    if ( $master_status ) {
-      my $sql = "SELECT MASTER_POS_WAIT('$master_status->{file}', "
+      my $server_version = VersionParser->new($slave_dbh);
-              . "$master_status->{position}, $timeout)";
+      my $channel_sql = $server_version > '5.6' && $self->{channel} ? ", '$self->{channel}'" : '';
+      my $sql = "SELECT MASTER_POS_WAIT('$master_status->{file}', $master_status->{position}, $timeout $channel_sql)";
       PTDEBUG && _d($slave_dbh, $sql);
       my $start = time;
       ($result) = $slave_dbh->selectrow_array($sql);

bin/pt-heartbeat

@@ -456,12 +456,31 @@ sub get_slave_status {
             ||= $dbh->prepare('SHOW SLAVE STATUS');
       PTDEBUG && _d($dbh, 'SHOW SLAVE STATUS');
       $sth->execute();
-      my ($ss) = @{$sth->fetchall_arrayref({})};
+      my ($sss_rows) = $sth->fetchall_arrayref({}); # Show Slave Status rows
+
+      my $ss;
+      if ( $sss_rows && @$sss_rows ) {
+          if (scalar @$sss_rows > 1) {
+              if (!$self->{channel}) {
+                  warn 'This server returned more than one row for SHOW SLAVE STATUS but "channel" was not specified on the command line';
+                  return undef;
+              }
+              for my $row (@$sss_rows) {
+                  $row = { map { lc($_) => $row->{$_} } keys %$row }; # lowercase the keys
+                  if ($row->{channel_name} eq $self->{channel}) {
+                      $ss = $row;
+                      last;
+                  }
+              }
+          } else {
+              $ss = $sss_rows->[0];
+          }
 
           if ( $ss && %$ss ) {
              $ss = { map { lc($_) => $ss->{$_} } keys %$ss }; # lowercase the keys
              return $ss;
           }
+      }
 
       PTDEBUG && _d('This server returns nothing for SHOW SLAVE STATUS');
       $self->{not_a_slave}->{$dbh}++;
@@ -505,8 +524,9 @@ sub wait_for_master {
    my $result;
    my $waited;
    if ( $master_status ) {
-      my $sql = "SELECT MASTER_POS_WAIT('$master_status->{file}', "
+      my $server_version = VersionParser->new($slave_dbh);
-              . "$master_status->{position}, $timeout)";
+      my $channel_sql = $server_version > '5.6' && $self->{channel} ? ", '$self->{channel}'" : '';
+      my $sql = "SELECT MASTER_POS_WAIT('$master_status->{file}', $master_status->{position}, $timeout $channel_sql)";
       PTDEBUG && _d($slave_dbh, $sql);
       my $start = time;
       ($result) = $slave_dbh->selectrow_array($sql);

bin/pt-kill

@@ -4133,12 +4133,31 @@ sub get_slave_status {
             ||= $dbh->prepare('SHOW SLAVE STATUS');
       PTDEBUG && _d($dbh, 'SHOW SLAVE STATUS');
       $sth->execute();
-      my ($ss) = @{$sth->fetchall_arrayref({})};
+      my ($sss_rows) = $sth->fetchall_arrayref({}); # Show Slave Status rows
+
+      my $ss;
+      if ( $sss_rows && @$sss_rows ) {
+          if (scalar @$sss_rows > 1) {
+              if (!$self->{channel}) {
+                  warn 'This server returned more than one row for SHOW SLAVE STATUS but "channel" was not specified on the command line';
+                  return undef;
+              }
+              for my $row (@$sss_rows) {
+                  $row = { map { lc($_) => $row->{$_} } keys %$row }; # lowercase the keys
+                  if ($row->{channel_name} eq $self->{channel}) {
+                      $ss = $row;
+                      last;
+                  }
+              }
+          } else {
+              $ss = $sss_rows->[0];
+          }
 
           if ( $ss && %$ss ) {
              $ss = { map { lc($_) => $ss->{$_} } keys %$ss }; # lowercase the keys
              return $ss;
           }
+      }
 
       PTDEBUG && _d('This server returns nothing for SHOW SLAVE STATUS');
       $self->{not_a_slave}->{$dbh}++;
@@ -4182,8 +4201,9 @@ sub wait_for_master {
    my $result;
    my $waited;
    if ( $master_status ) {
-      my $sql = "SELECT MASTER_POS_WAIT('$master_status->{file}', "
+      my $server_version = VersionParser->new($slave_dbh);
-              . "$master_status->{position}, $timeout)";
+      my $channel_sql = $server_version > '5.6' && $self->{channel} ? ", '$self->{channel}'" : '';
+      my $sql = "SELECT MASTER_POS_WAIT('$master_status->{file}', $master_status->{position}, $timeout $channel_sql)";
       PTDEBUG && _d($slave_dbh, $sql);
       my $start = time;
       ($result) = $slave_dbh->selectrow_array($sql);

bin/pt-online-schema-change

@@ -4415,12 +4415,31 @@ sub get_slave_status {
             ||= $dbh->prepare('SHOW SLAVE STATUS');
       PTDEBUG && _d($dbh, 'SHOW SLAVE STATUS');
       $sth->execute();
-      my ($ss) = @{$sth->fetchall_arrayref({})};
+      my ($sss_rows) = $sth->fetchall_arrayref({}); # Show Slave Status rows
+
+      my $ss;
+      if ( $sss_rows && @$sss_rows ) {
+          if (scalar @$sss_rows > 1) {
+              if (!$self->{channel}) {
+                  warn 'This server returned more than one row for SHOW SLAVE STATUS but "channel" was not specified on the command line';
+                  return undef;
+              }
+              for my $row (@$sss_rows) {
+                  $row = { map { lc($_) => $row->{$_} } keys %$row }; # lowercase the keys
+                  if ($row->{channel_name} eq $self->{channel}) {
+                      $ss = $row;
+                      last;
+                  }
+              }
+          } else {
+              $ss = $sss_rows->[0];
+          }
 
           if ( $ss && %$ss ) {
              $ss = { map { lc($_) => $ss->{$_} } keys %$ss }; # lowercase the keys
              return $ss;
           }
+      }
 
       PTDEBUG && _d('This server returns nothing for SHOW SLAVE STATUS');
       $self->{not_a_slave}->{$dbh}++;
@@ -4464,8 +4483,9 @@ sub wait_for_master {
    my $result;
    my $waited;
    if ( $master_status ) {
-      my $sql = "SELECT MASTER_POS_WAIT('$master_status->{file}', "
+      my $server_version = VersionParser->new($slave_dbh);
-              . "$master_status->{position}, $timeout)";
+      my $channel_sql = $server_version > '5.6' && $self->{channel} ? ", '$self->{channel}'" : '';
+      my $sql = "SELECT MASTER_POS_WAIT('$master_status->{file}', $master_status->{position}, $timeout $channel_sql)";
       PTDEBUG && _d($slave_dbh, $sql);
       my $start = time;
       ($result) = $slave_dbh->selectrow_array($sql);

bin/pt-query-digest

@@ -10750,12 +10750,31 @@ sub get_slave_status {
             ||= $dbh->prepare('SHOW SLAVE STATUS');
       PTDEBUG && _d($dbh, 'SHOW SLAVE STATUS');
       $sth->execute();
-      my ($ss) = @{$sth->fetchall_arrayref({})};
+      my ($sss_rows) = $sth->fetchall_arrayref({}); # Show Slave Status rows
+
+      my $ss;
+      if ( $sss_rows && @$sss_rows ) {
+          if (scalar @$sss_rows > 1) {
+              if (!$self->{channel}) {
+                  warn 'This server returned more than one row for SHOW SLAVE STATUS but "channel" was not specified on the command line';
+                  return undef;
+              }
+              for my $row (@$sss_rows) {
+                  $row = { map { lc($_) => $row->{$_} } keys %$row }; # lowercase the keys
+                  if ($row->{channel_name} eq $self->{channel}) {
+                      $ss = $row;
+                      last;
+                  }
+              }
+          } else {
+              $ss = $sss_rows->[0];
+          }
 
           if ( $ss && %$ss ) {
              $ss = { map { lc($_) => $ss->{$_} } keys %$ss }; # lowercase the keys
              return $ss;
           }
+      }
 
       PTDEBUG && _d('This server returns nothing for SHOW SLAVE STATUS');
       $self->{not_a_slave}->{$dbh}++;
@@ -10799,8 +10818,9 @@ sub wait_for_master {
    my $result;
    my $waited;
    if ( $master_status ) {
-      my $sql = "SELECT MASTER_POS_WAIT('$master_status->{file}', "
+      my $server_version = VersionParser->new($slave_dbh);
-              . "$master_status->{position}, $timeout)";
+      my $channel_sql = $server_version > '5.6' && $self->{channel} ? ", '$self->{channel}'" : '';
+      my $sql = "SELECT MASTER_POS_WAIT('$master_status->{file}', $master_status->{position}, $timeout $channel_sql)";
       PTDEBUG && _d($slave_dbh, $sql);
       my $start = time;
       ($result) = $slave_dbh->selectrow_array($sql);

bin/pt-slave-find

@@ -2570,12 +2570,31 @@ sub get_slave_status {
             ||= $dbh->prepare('SHOW SLAVE STATUS');
       PTDEBUG && _d($dbh, 'SHOW SLAVE STATUS');
       $sth->execute();
-      my ($ss) = @{$sth->fetchall_arrayref({})};
+      my ($sss_rows) = $sth->fetchall_arrayref({}); # Show Slave Status rows
+
+      my $ss;
+      if ( $sss_rows && @$sss_rows ) {
+          if (scalar @$sss_rows > 1) {
+              if (!$self->{channel}) {
+                  warn 'This server returned more than one row for SHOW SLAVE STATUS but "channel" was not specified on the command line';
+                  return undef;
+              }
+              for my $row (@$sss_rows) {
+                  $row = { map { lc($_) => $row->{$_} } keys %$row }; # lowercase the keys
+                  if ($row->{channel_name} eq $self->{channel}) {
+                      $ss = $row;
+                      last;
+                  }
+              }
+          } else {
+              $ss = $sss_rows->[0];
+          }
 
           if ( $ss && %$ss ) {
              $ss = { map { lc($_) => $ss->{$_} } keys %$ss }; # lowercase the keys
              return $ss;
           }
+      }
 
       PTDEBUG && _d('This server returns nothing for SHOW SLAVE STATUS');
       $self->{not_a_slave}->{$dbh}++;
@@ -2619,8 +2638,9 @@ sub wait_for_master {
    my $result;
    my $waited;
    if ( $master_status ) {
-      my $sql = "SELECT MASTER_POS_WAIT('$master_status->{file}', "
+      my $server_version = VersionParser->new($slave_dbh);
-              . "$master_status->{position}, $timeout)";
+      my $channel_sql = $server_version > '5.6' && $self->{channel} ? ", '$self->{channel}'" : '';
+      my $sql = "SELECT MASTER_POS_WAIT('$master_status->{file}', $master_status->{position}, $timeout $channel_sql)";
       PTDEBUG && _d($slave_dbh, $sql);
       my $start = time;
       ($result) = $slave_dbh->selectrow_array($sql);

bin/pt-slave-restart

@@ -2981,12 +2981,31 @@ sub get_slave_status {
             ||= $dbh->prepare('SHOW SLAVE STATUS');
       PTDEBUG && _d($dbh, 'SHOW SLAVE STATUS');
       $sth->execute();
-      my ($ss) = @{$sth->fetchall_arrayref({})};
+      my ($sss_rows) = $sth->fetchall_arrayref({}); # Show Slave Status rows
+
+      my $ss;
+      if ( $sss_rows && @$sss_rows ) {
+          if (scalar @$sss_rows > 1) {
+              if (!$self->{channel}) {
+                  warn 'This server returned more than one row for SHOW SLAVE STATUS but "channel" was not specified on the command line';
+                  return undef;
+              }
+              for my $row (@$sss_rows) {
+                  $row = { map { lc($_) => $row->{$_} } keys %$row }; # lowercase the keys
+                  if ($row->{channel_name} eq $self->{channel}) {
+                      $ss = $row;
+                      last;
+                  }
+              }
+          } else {
+              $ss = $sss_rows->[0];
+          }
 
           if ( $ss && %$ss ) {
              $ss = { map { lc($_) => $ss->{$_} } keys %$ss }; # lowercase the keys
              return $ss;
           }
+      }
 
       PTDEBUG && _d('This server returns nothing for SHOW SLAVE STATUS');
       $self->{not_a_slave}->{$dbh}++;
@@ -3030,8 +3049,9 @@ sub wait_for_master {
    my $result;
    my $waited;
    if ( $master_status ) {
-      my $sql = "SELECT MASTER_POS_WAIT('$master_status->{file}', "
+      my $server_version = VersionParser->new($slave_dbh);
-              . "$master_status->{position}, $timeout)";
+      my $channel_sql = $server_version > '5.6' && $self->{channel} ? ", '$self->{channel}'" : '';
+      my $sql = "SELECT MASTER_POS_WAIT('$master_status->{file}', $master_status->{position}, $timeout $channel_sql)";
       PTDEBUG && _d($slave_dbh, $sql);
       my $start = time;
       ($result) = $slave_dbh->selectrow_array($sql);

bin/pt-table-checksum

@@ -5361,12 +5361,31 @@ sub get_slave_status {
             ||= $dbh->prepare('SHOW SLAVE STATUS');
       PTDEBUG && _d($dbh, 'SHOW SLAVE STATUS');
       $sth->execute();
-      my ($ss) = @{$sth->fetchall_arrayref({})};
+      my ($sss_rows) = $sth->fetchall_arrayref({}); # Show Slave Status rows
+
+      my $ss;
+      if ( $sss_rows && @$sss_rows ) {
+          if (scalar @$sss_rows > 1) {
+              if (!$self->{channel}) {
+                  warn 'This server returned more than one row for SHOW SLAVE STATUS but "channel" was not specified on the command line';
+                  return undef;
+              }
+              for my $row (@$sss_rows) {
+                  $row = { map { lc($_) => $row->{$_} } keys %$row }; # lowercase the keys
+                  if ($row->{channel_name} eq $self->{channel}) {
+                      $ss = $row;
+                      last;
+                  }
+              }
+          } else {
+              $ss = $sss_rows->[0];
+          }
 
           if ( $ss && %$ss ) {
              $ss = { map { lc($_) => $ss->{$_} } keys %$ss }; # lowercase the keys
              return $ss;
           }
+      }
 
       PTDEBUG && _d('This server returns nothing for SHOW SLAVE STATUS');
       $self->{not_a_slave}->{$dbh}++;
@@ -5410,8 +5429,9 @@ sub wait_for_master {
    my $result;
    my $waited;
    if ( $master_status ) {
-      my $sql = "SELECT MASTER_POS_WAIT('$master_status->{file}', "
+      my $server_version = VersionParser->new($slave_dbh);
-              . "$master_status->{position}, $timeout)";
+      my $channel_sql = $server_version > '5.6' && $self->{channel} ? ", '$self->{channel}'" : '';
+      my $sql = "SELECT MASTER_POS_WAIT('$master_status->{file}', $master_status->{position}, $timeout $channel_sql)";
       PTDEBUG && _d($slave_dbh, $sql);
       my $start = time;
       ($result) = $slave_dbh->selectrow_array($sql);

bin/pt-table-sync

@@ -6945,39 +6945,29 @@ sub get_slave_status {
       $sth->execute();
       my ($sss_rows) = $sth->fetchall_arrayref({}); # Show Slave Status rows
 
-      warn ">>>>====================================================================================================";
-      warn Data::Dumper::Dumper($sss_rows);
-      warn ">>>>====================================================================================================";
-      # If SHOW SLAVE STATUS returns more than one row it means that this slave is connected to more
-      # than one master using replication channels.
-      # If we have a channel name as a parameter, we need to select the correct row and return it.
-      # If we don't have a channel name as a parameter, there is no way to know what the correct master is so,
-      # return an error.
       my $ss;
-      $self->{channel} = 'masterchan2';
+      if ( $sss_rows && @$sss_rows ) {
-      if ( $sss_rows && @$sss_rows && scalar @$sss_rows > 1) {
+          if (scalar @$sss_rows > 1) {
-        warn "KKKKKKKKKKKKKKKKKK";
               if (!$self->{channel}) {
                   warn 'This server returned more than one row for SHOW SLAVE STATUS but "channel" was not specified on the command line';
-              $self->{not_a_slave}->{$dbh}++;
+                  return undef;
-              return;
               }
               for my $row (@$sss_rows) {
-              if ($row->{Channel_Name} eq $self->{channel}) {
+                  $row = { map { lc($_) => $row->{$_} } keys %$row }; # lowercase the keys
+                  if ($row->{channel_name} eq $self->{channel}) {
                       $ss = $row;
                       last;
                   }
               }
           } else {
-          warn "MMMMMMMMMMMMMMMMMMMMMMMMM";
               $ss = $sss_rows->[0];
           }
 
-
           if ( $ss && %$ss ) {
              $ss = { map { lc($_) => $ss->{$_} } keys %$ss }; # lowercase the keys
              return $ss;
           }
+      }
 
       PTDEBUG && _d('This server returns nothing for SHOW SLAVE STATUS');
       $self->{not_a_slave}->{$dbh}++;
@@ -7021,20 +7011,15 @@ sub wait_for_master {
    my $result;
    my $waited;
    if ( $master_status ) {
-      my $sql = "SELECT MASTER_POS_WAIT('$master_status->{file}', "
+      my $server_version = VersionParser->new($slave_dbh);
-              . "$master_status->{position}, $timeout)";
+      my $channel_sql = $server_version > '5.6' && $self->{channel} ? ", '$self->{channel}'" : '';
+      my $sql = "SELECT MASTER_POS_WAIT('$master_status->{file}', $master_status->{position}, $timeout $channel_sql)";
       PTDEBUG && _d($slave_dbh, $sql);
       my $start = time;
-      $result = $slave_dbh->selectrow_array($sql);
+      ($result) = $slave_dbh->selectrow_array($sql);
-      warn ">>>";
-      warn Data::Dumper::Dumper($result);
 
       $waited = time - $start;
 
-      warn "====================================================================================================";
-      warn "slave_dbh $slave_dbh";
-      warn Data::Dumper::Dumper($slave_dbh);
-      warn Data::Dumper::Dumper($master_status);
       PTDEBUG && _d('Result of waiting:', $result);
       PTDEBUG && _d("Waited", $waited, "seconds");
    }
@@ -9884,7 +9869,7 @@ sub main {
    # Do the work.
    # ########################################################################
    my $tp        = new TableParser( Quoter => $q );
-   my $ms        = new MasterSlave(OptionParser=>$o,DSNParser=>$dp,Quoter=>$q);
+   my $ms        = new MasterSlave(OptionParser=>$o,DSNParser=>$dp,Quoter=>$q, channel=>$o->get('channel'));
    my $rt        = new Retry();
    my $chunker   = new TableChunker( Quoter => $q, TableParser => $tp );
    my $nibbler   = new TableNibbler( Quoter => $q, TableParser => $tp );
@@ -12055,6 +12040,18 @@ For most non-trivial data sizes, you want to leave this option enabled.
 
 This option is disabled when L<"--bidirectional"> is used.
 
+=item --channel
+
+type: string
+
+Channel name used when connected to a server using replication channels.
+Suppose you have two masters, master_a at port 12345, master_b at port 1236 and
+a slave connected to both masters using channels chan_master_a and chan_master_b.
+If you want to run pt-table-sync to syncronize the slave against master_a, pt-table-sync
+won't be able to determine what's the correct master since SHOW SLAVE STATUS
+will return 2 rows. In this case, you can use --channel=chan_master_a to specify
+the channel name to use in the SHOW SLAVE STATUS command.
+
 =item --charset
 
 short form: -A; type: string

lib/MasterSlave.pm

@@ -430,17 +430,42 @@ sub get_master_dsn {
 # Gets SHOW SLAVE STATUS, with column names all lowercased, as a hashref.
 sub get_slave_status {
    my ( $self, $dbh ) = @_;
+
    if ( !$self->{not_a_slave}->{$dbh} ) {
       my $sth = $self->{sths}->{$dbh}->{SLAVE_STATUS}
             ||= $dbh->prepare('SHOW SLAVE STATUS');
       PTDEBUG && _d($dbh, 'SHOW SLAVE STATUS');
       $sth->execute();
-      my ($ss) = @{$sth->fetchall_arrayref({})};
+      my ($sss_rows) = $sth->fetchall_arrayref({}); # Show Slave Status rows
+
+      # If SHOW SLAVE STATUS returns more than one row it means that this slave is connected to more
+      # than one master using replication channels.
+      # If we have a channel name as a parameter, we need to select the correct row and return it.
+      # If we don't have a channel name as a parameter, there is no way to know what the correct master is so,
+      # return an error.
+      my $ss;
+      if ( $sss_rows && @$sss_rows ) {
+          if (scalar @$sss_rows > 1) {
+              if (!$self->{channel}) {
+                  warn 'This server returned more than one row for SHOW SLAVE STATUS but "channel" was not specified on the command line';
+                  return undef;
+              }
+              for my $row (@$sss_rows) {
+                  $row = { map { lc($_) => $row->{$_} } keys %$row }; # lowercase the keys
+                  if ($row->{channel_name} eq $self->{channel}) {
+                      $ss = $row;
+                      last;
+                  }
+              }
+          } else {
+              $ss = $sss_rows->[0];
+          }
 
           if ( $ss && %$ss ) {
              $ss = { map { lc($_) => $ss->{$_} } keys %$ss }; # lowercase the keys
              return $ss;
           }
+      }
 
       PTDEBUG && _d('This server returns nothing for SHOW SLAVE STATUS');
       $self->{not_a_slave}->{$dbh}++;
@@ -506,8 +531,9 @@ sub wait_for_master {
    my $result;
    my $waited;
    if ( $master_status ) {
-      my $sql = "SELECT MASTER_POS_WAIT('$master_status->{file}', "
+      my $server_version = VersionParser->new($slave_dbh);
-              . "$master_status->{position}, $timeout)";
+      my $channel_sql = $server_version > '5.6' && $self->{channel} ? ", '$self->{channel}'" : '';
+      my $sql = "SELECT MASTER_POS_WAIT('$master_status->{file}', $master_status->{position}, $timeout $channel_sql)";
       PTDEBUG && _d($slave_dbh, $sql);
       my $start = time;
       ($result) = $slave_dbh->selectrow_array($sql);

sandbox/gtid_on.sql

@@ -1,3 +1,4 @@
+STOP SLAVE FOR CHANNEL '';
 SET GLOBAL master_info_repository = 'TABLE';
 SET @@GLOBAL.relay_log_info_repository = 'TABLE';
 SET @@GLOBAL.ENFORCE_GTID_CONSISTENCY=ON;

t/lib/MasterSlave.t

@@ -750,6 +750,70 @@ like(
    "--recursion-method none,none"
 );
 
+SKIP: {
+
+   skip "Only test on mysql 5.7" if ( $sandbox_version lt '5.7' );
+
+   my ($master1_dbh, $master1_dsn) = $sb->start_sandbox(
+      server => 'chan_master1',
+      type   => 'master',
+   );
+   my ($master2_dbh, $master2_dsn) = $sb->start_sandbox(
+      server => 'chan_master2',
+      type   => 'master',
+   );
+   my ($slave1_dbh, $slave1_dsn) = $sb->start_sandbox(
+      server => 'chan_slave1',
+      type   => 'master',
+   );
+   my $slave1_port = $sb->port_for('chan_slave1');
+   
+   $sb->load_file('chan_master1', "sandbox/gtid_on.sql", undef, no_wait => 1);
+   $sb->load_file('chan_master2', "sandbox/gtid_on.sql", undef, no_wait => 1);
+   $sb->load_file('chan_slave1', "sandbox/slave_channels.sql", undef, no_wait => 1);
+                                                             
+   my $chan_slaves = $ms->get_slaves(
+      dbh      => $master1_dbh,
+      dsn      => $master1_dsn,
+      make_cxn => sub {
+         my $cxn = new Cxn(
+            @_,
+            DSNParser    => $dp,
+            OptionParser => $o,
+         );
+         $cxn->connect();
+         return $cxn;
+      },
+   );
+
+   our $message;
+   local $SIG{__WARN__} = sub {
+      $message = shift;
+   };
+   my $css = $ms->get_slave_status($slave1_dbh);
+   local $SIG{__WARN__} = undef;
+   is (
+       $css,
+       undef,
+       'Cannot determine slave in a multi source config without --channel param'
+   );
+   like (
+       $message,
+       qr/This server returned more than one row for SHOW SLAVE STATUS/,
+       'Got warning message if we cannot determine slave in a multi source config without --channel param',
+   );
+
+   # Now try specifying a channel name 
+   $ms->{channel} = 'masterchan1';
+   $css = $ms->get_slave_status($slave1_dbh);
+   is (
+       $css->{channel_name},
+       'masterchan1',
+       'Returned the correct slave',
+   );
+
+   $sb->stop_sandbox(qw(chan_master1 chan_master2 chan_slave1));
+}
 # #############################################################################
 # Done.
 # #############################################################################