PT-1574 Improved detection of nullable keys

bin/pt-online-schema-change

@@ -9275,13 +9275,12 @@ sub main {
    {
       my $indexes = $new_tbl->{tbl_struct}->{keys}; # brevity
       foreach my $index ( $tp->sort_indexes($new_tbl->{tbl_struct}) ) {
-         if ( $index eq 'PRIMARY' || $indexes->{$index}->{is_unique} ) {
+         if ( $index eq 'PRIMARY' || ($indexes->{$index}->{is_unique} && $indexes->{$index}->{is_nullable} == 0)) {
             PTDEBUG && _d('Delete trigger new index:', Dumper($index));
             $new_tbl->{del_index} = $index;
             last;
          }
       }
-      PTDEBUG && _d('New table delete index:', $new_tbl->{del_index});
    }
 
    {
@@ -9298,7 +9297,8 @@ sub main {
 
    if ( !$new_tbl->{del_index} ) {
       die "The new table $new_tbl->{name} does not have a PRIMARY KEY "
-        . "or a unique index which is required for the DELETE trigger.\n";
+        . "or a unique index which is required for the DELETE trigger.\n"
+        . "Please check you have at least one UNIQUE and NOT NULLABLE index.\n";
    }
 
    # Determine whether to use the new or orig table delete index.

t/pt-online-schema-change/pt-1574.t

@@ -0,0 +1,73 @@
+#!/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 threads;
+use threads::shared;
+use Thread::Semaphore;
+
+use English qw(-no_match_vars);
+use Test::More;
+
+use Data::Dumper;
+use PerconaTest;
+use Sandbox;
+use SqlModes;
+use File::Temp qw/ tempdir /;
+
+if ($sandbox_version lt '5.7') {
+    plan skip_all => 'This test needs MySQL 5.7+';
+} else {
+    plan tests => 3;
+}    
+
+require "$trunk/bin/pt-online-schema-change";
+
+my $dp = new DSNParser(opts=>$dsn_opts);
+my $sb = new Sandbox(basedir => '/tmp', DSNParser => $dp);
+
+my $dbh = $sb->get_dbh_for('master');
+my $dsn = $sb->dsn_for("master");
+
+# The sandbox servers run with lock_wait_timeout=3 and it's not dynamic
+# so we need to specify --set-vars innodb_lock_wait_timeout=3 else the
+# tool will die.
+my @args = (qw(--set-vars innodb_lock_wait_timeout=3));
+my $output;
+my $exit_status;
+
+$sb->load_file('master', "t/pt-online-schema-change/samples/pt-1574.sql");
+
+($output, $exit_status) = full_output(
+    sub { pt_online_schema_change::main(@args, "$dsn,D=test,t=t1",
+            '--execute', "--chunk-index", "idx_id", "--chunk-size", "1", 
+            "--nocheck-plan", '--alter', "engine=innodb",
+        ),
+    },
+    stderr => 1,
+);
+
+isnt(
+    $exit_status,
+    0,
+    "PT-1544 There is no unique index exit status",
+);
+
+like(
+    $output,
+    qr/at least one UNIQUE and NOT NULLABLE index/s,
+    "PT-1544 Message you need an unique index.",
+);
+
+# #############################################################################
+# Done.
+# #############################################################################
+$sb->wipe_clean($dbh);
+ok($sb->ok(), "Sandbox servers") or BAIL_OUT(__FILE__ . " broke the sandbox");
+done_testing;

t/pt-online-schema-change/samples/pt-1574.sql

@@ -0,0 +1,22 @@
+DROP DATABASE IF EXISTS test;
+CREATE DATABASE test;
+USE test;
+
+CREATE TABLE `test`.`t1` (
+`id` int(11) DEFAULT NULL,
+`site_name` varchar(25) DEFAULT NULL,
+`last_update` datetime DEFAULT NULL,
+UNIQUE KEY `idx_id` (`id`),
+KEY `idx_last_update` (`last_update`),
+KEY `idx_site_name` (`site_name`)
+) ENGINE=InnoDB DEFAULT CHARSET=latin1;
+
+INSERT INTO `t1` VALUES 
+(1385108873,'Carolyn Ryan','2018-01-13 17:05:24'),
+(2140660022,'Patricia Garza','2018-01-13 19:07:51'),
+(1473481373,'Rachel George','2017-12-05 21:09:53'),
+(1394124308,'Mrs. Ms. Miss Janet Dixon','2017-10-28 07:07:41'),
+(1978918050,'Louis Gray Jr. Sr. I II I','2017-11-01 22:10:39'),
+(1275940242,'Lois Spencer','2018-02-22 01:01:38'),
+(NULL,NULL,NULL),
+(NULL,NULL,NULL);