pt-osc generate random table prefix after 10th try

bin/pt-online-schema-change

@@ -9546,6 +9546,7 @@ sub main {
 
    my $old_tbl;
    if ( $o->get('swap-tables') ) {
+
       eval {
          $old_tbl = swap_tables(
             orig_tbl      => $orig_tbl,
@@ -10084,7 +10085,7 @@ sub swap_tables {
 
    my $prefix       = '_';
    my $table_name   = $orig_tbl->{tbl} . ($args{suffix} || '');
-   my $name_tries   = 10;  # don't try forever
+   my $name_tries   = 20;  # don't try forever
    my $table_exists = qr/table.+?already exists/i;
 
    # This sub only works for --execute.  Since the options are
@@ -10119,6 +10120,16 @@ sub swap_tables {
 
       print ts("Swapping tables...\n");
       while ( $name_tries-- ) {
+       
+         # https://bugs.launchpad.net/percona-toolkit/+bug/1526105
+         if ( $name_tries <= 10 ) { # we've already added 10 underscores?
+            # time to try a small random string
+            my @chars = ("A".."Z", "0".."9");
+            $prefix = '';
+            $prefix .= $chars[rand @chars] for 1..6;
+            $prefix .= "_";  
+         }
+
          $table_name = $prefix . $table_name;
 
          if ( length($table_name) > 64 ) {
@@ -10131,6 +10142,7 @@ sub swap_tables {
          my $sql = "RENAME TABLE $orig_tbl->{name} "
                  . "TO " . $q->quote($orig_tbl->{db}, $table_name)
                  . ", $new_tbl->{name} TO $orig_tbl->{name}"; 
+
          eval {
             osc_retry(
                Cxn     => $cxn,
@@ -10150,6 +10162,7 @@ sub swap_tables {
                   # other purposes.
                   $table_exists,
                ],
+               operation => "swap_tables",
             );
          };
          if ( my $e = $EVAL_ERROR ) {
@@ -10169,10 +10182,8 @@ sub swap_tables {
             name => $q->quote($orig_tbl->{db}, $table_name),
          };
       }
-
+     
       # This shouldn't happen.
-      # Here and in the attempt to find a new table name we probably ought to
-      # use --tries (and maybe a Retry object?)
       die ts("Failed to find a unique old table name after "
          . "serveral attempts.\n");
    }
@@ -10699,6 +10710,9 @@ sub osc_retry {
          PTDEBUG && _d('Retry fail:', $error);
 
          if ( $ignore_errors ) {
+            if ($error =~ /table.+?already exists/i) {
+               PTDEBUG && _d('Aborting retries because of table name conflict. Trying with different name');
+            }
             return 0 if grep { $error =~ $_ } @$ignore_errors;
          }
 
@@ -10901,6 +10915,7 @@ sub sig_int {
    exit 1;
 }
 
+
 sub _d {
    my ($package, undef, $line) = caller 0;
    @_ = map { (my $temp = $_) =~ s/\n/\n# /g; $temp; }

t/pt-online-schema-change/bugs.t

@@ -38,7 +38,6 @@ my $output;
 my $exit_status;
 my $sample  = "t/pt-online-schema-change/samples/";
 
-
 # ############################################################################
 # https://bugs.launchpad.net/percona-toolkit/+bug/1336734
 # pt-online-schema-change 2.2.17 adds --null-to-not-null feature
@@ -544,6 +543,40 @@ ok ((!$exit_status && $output =~ /success/i) , "--set-vars sql_mode=\\'a\\\\,b\\
 $master_dbh->do("drop database test");
 $modes->restore_original_modes();
 
+# ############################################################################
+# https://bugs.launchpad.net/percona-toolkit/+bug/1526105 
+# Not necessarily a bug, but more of an enhancement.
+# ############################################################################
+
+# We will run pt-osc more than 10 times using --no-drop-old-table and expect 
+# no errors.
+
+$sb->load_file('master', "$sample/simple_test_table.sql");
+
+my $errors    = 0;
+my $successes = 0;
+for (1..12) {
+   ($output, $exit_status) = full_output(
+      sub { pt_online_schema_change::main(@args, 
+         "$master_dsn,D=test,t=test",
+         "--execute",
+         "--no-drop-old-table",
+         "--alter", "ENGINE=InnoDB",
+         ) },
+   );
+   if ($exit_status) {
+      $errors++;
+   }
+   if ( $output =~ /Successfully/i ) {
+      $successes++;
+   }
+}
+
+ok ( (!$errors && $successes == 12), "Issue #1526105 - no-drop-old-table fails after 10 tries" );
+
+$master_dbh->do("DROP DATABASE IF EXISTS test");
+
+
 # #############################################################################
 # Done.
 # #############################################################################

t/pt-online-schema-change/samples/simple_test_table.sql

@@ -0,0 +1,9 @@
+DROP DATABASE IF EXISTS test;
+CREATE DATABASE test;
+USE test;
+CREATE TABLE `test` (
+  `id` int(11) NOT NULL,
+  `name` varchar(20) DEFAULT NULL,
+  PRIMARY KEY (`id`)
+) ENGINE=InnoDB;
+