Add --[no]drop-triggers to pt-online-schema-change.

bin/pt-online-schema-change

@@ -7845,6 +7845,10 @@ sub main {
       $o->save_error($EVAL_ERROR);
    }
 
+   if ( !$o->get('drop-triggers') ) {
+      $o->set('drop-old-table', 0);
+   }
+
    if ( !$o->get('help') ) {
       if ( @ARGV ) {
          $o->save_error('Specify only one DSN on the command line');
@@ -8659,17 +8663,29 @@ sub main {
    # Drop the triggers.  We can save this cleanup task before
    # adding the triggers because if adding them fails, this will be
    # called which will drop whichever triggers were created.
+   my $drop_triggers = $o->get('drop-triggers');
    push @cleanup_tasks, sub {
       PTDEBUG && _d('Clean up triggers');
       # --plugin hook
       if ( $plugin && $plugin->can('before_drop_triggers') ) {
          $plugin->before_drop_triggers(
             oktorun           => $oktorun,
+            drop_triggers     => $drop_triggers,
             drop_trigger_sqls => \@drop_trigger_sqls,
          );
       }
 
-      if ( $oktorun ) {
+      if ( !$oktorun ) {
+         print "Not dropping triggers because the tool was interrupted.  "
+             . "To drop the triggers, execute:\n"
+             . join("\n", @drop_trigger_sqls) . "\n";
+      }
+      elsif ( !$drop_triggers ) {
+         print "Not dropping triggers because --no-drop-triggers was "
+         . "specified.  To drop the triggers, execute:\n"
+         . join("\n", @drop_trigger_sqls) . "\n";
+      }
+      else {
          drop_triggers(
             tbl          => $orig_tbl,
             Cxn          => $cxn,
@@ -8680,11 +8696,6 @@ sub main {
             stats        => \%stats,
          );
       }
-      else {
-         print "Not dropping triggers because the tool was interrupted.  "
-             . "To drop the triggers, execute:\n"
-             . join("\n", @drop_trigger_sqls) . "\n";
-      }
    };
 
    # --plugin hook
@@ -9231,6 +9242,12 @@ sub main {
          }
       }
    }
+   elsif ( !$drop_triggers ) {
+      print "Not dropping old table because --no-drop-triggers was specified.\n";
+   }
+   else {
+      print "Not dropping old table because --no-drop-old-table was specified.\n";
+   }
 
    # ########################################################################
    # Done.
@@ -10943,6 +10960,13 @@ the tool leaves the original table in place.
 
 If C<--no-swap-tables> is specified, then there is no old table to drop.
 
+=item --[no]drop-triggers
+
+default: yes
+
+Drop triggers on the old table.  C<--no-drop-triggers> forces
+C<--no-drop-old-table>.
+
 =item --dry-run
 
 Create and alter the new table, but do not create triggers, copy data, or

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

@@ -576,7 +576,7 @@ SKIP: {
 }
 
 # #############################################################################
-# --alther-foreign-keys-method=none.  This intentionally breaks fks because
+# --alter-foreign-keys-method=none.  This intentionally breaks fks because
 # they're not updated so they'll point to the old table that is dropped.
 # #############################################################################
 

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

@@ -0,0 +1,76 @@
+#!/usr/bin/env perl
+
+BEGIN {
+   die "The PERCONA_TOOLKIT_BRANCH environment variable is not set.\n"
+      unless $ENV{PERCONA_TOOLKIT_BRANCH} && -d $ENV{PERCONA_TOOLKIT_BRANCH};
+   unshift @INC, "$ENV{PERCONA_TOOLKIT_BRANCH}/lib";
+};
+
+use strict;
+use warnings FATAL => 'all';
+use English qw(-no_match_vars);
+use Test::More;
+
+use PerconaTest;
+use Sandbox;
+require "$trunk/bin/pt-online-schema-change";
+require VersionParser;
+
+use Time::HiRes qw(sleep);
+use Data::Dumper;
+$Data::Dumper::Indent    = 1;
+$Data::Dumper::Sortkeys  = 1;
+$Data::Dumper::Quotekeys = 0;
+
+my $dp         = new DSNParser(opts=>$dsn_opts);
+my $sb         = new Sandbox(basedir => '/tmp', DSNParser => $dp);
+my $dbh1 = $sb->get_dbh_for('master');
+my $dbh2 = $sb->get_dbh_for('master');
+
+if ( !$dbh1 || !$dbh2 ) {
+   plan skip_all => 'Cannot connect to sandbox master';
+}
+
+my $output;
+my $master_dsn = $sb->dsn_for('master');
+my $sample     = "t/pt-online-schema-change/samples";
+my $plugin     = "$trunk/$sample/plugins";
+my $exit;
+my $rows;
+
+# Loads pt_osc.t with cols id (pk), c (unique index),, d.
+$sb->load_file('master', "$sample/basic_no_fks_innodb.sql");
+
+# #############################################################################
+# --no-swap-tables --no-drop-triggers
+# #############################################################################
+
+$output = output(
+   sub { pt_online_schema_change::main(
+      "$master_dsn,D=pt_osc,t=t",
+      '--alter', 'DROP COLUMN d',
+      qw(--execute --no-swap-tables --no-drop-new-table --no-drop-triggers))
+   },
+   stderr => 1,
+);
+
+my $triggers = $dbh1->selectall_arrayref("SHOW TRIGGERS FROM pt_osc");
+is(
+   @$triggers,
+   3,
+   "no swap-tables, drop-triggers, drop-new-table: triggers"
+) or diag(Dumper($triggers), $output);
+
+my $tables = $dbh1->selectall_arrayref("SHOW TABLES FROM pt_osc");
+is_deeply(
+   $tables,
+   [ ['_t_new'], ['t'] ],
+   "no swap-tables, drop-triggers, drop-new-table: tables"
+) or diag(Dumper($tables), $output);
+
+# #############################################################################
+# Done.
+# #############################################################################
+$sb->wipe_clean($dbh1);
+ok($sb->ok(), "Sandbox servers") or BAIL_OUT(__FILE__ . " broke the sandbox");
+done_testing;