Make pt-table-checksum always create the database/table it needs

bin/pt-table-checksum

@@ -8145,14 +8145,32 @@ sub check_repl_table {
    my $sql = "SHOW DATABASES LIKE '$db'";
    PTDEBUG && _d($sql);
    my @db_exists = $dbh->selectrow_array($sql);
-   if ( !@db_exists && $o->get('create-replicate-table') ) {
-      $sql = "CREATE DATABASE " . $q->quote($db) . " /* pt-table-checksum */";
+   if ( !@db_exists && !$o->get('create-replicate-table') ) {
+      die "--replicate database $db does not exist and "
+         . "--no-create-replicate-table was passed in.  You need "
+         . "to create the database.\n";
+   }
+
+   if ( $o->get('create-replicate-table') ) {
+      $sql = "CREATE DATABASE IF NOT EXISTS "
+            . $q->quote($db)
+            . " /* pt-table-checksum */";
+      local $@;
+      PTDEBUG && _d($sql);
       eval {
          $dbh->do($sql);
       };
       if ( $EVAL_ERROR ) {
+         if ( @db_exists ) {
+            print STDERR "CREATE DATABASE IF NOT EXISTS $db failed, but the "
+                     . "db already exists.  This is harmless unless the "
+                     . "slaves don't have the database. $EVAL_ERROR"; # kb link?
+         }
+         else {
             die "--replicate database $db does not exist and it cannot be "
-            . "created automatically.  You need to create the database.\n";
+               . "created automatically.  You need to create the database. "
+               . $EVAL_ERROR;
+         }
       }
    }
    
@@ -8165,18 +8183,32 @@ sub check_repl_table {
       db  => $db,
       tbl => $tbl,
    );
-   if ( !$tbl_exists ) {
+
+   # Always create the table, unless --no-create-replicate-table
+   # was passed in; see https://bugs.launchpad.net/percona-toolkit/+bug/950294
+   if ( !$tbl_exists && !$o->get('create-replicate-table') ) {
+      die "--replicate table $repl_table does not exist and "
+        . "--no-create-replicate-table was passed in.  "
+        . "You need to create the table.\n";
+   }
    if ( $o->get('create-replicate-table') ) {
-         create_repl_table(%args)
+      local $@;
+      eval {
+         create_repl_table(%args);
+      };
+      if ( $EVAL_ERROR ) {
+         if ( $tbl_exists ) {
+            print STDERR "CREATE TABLE IF NOT EXISTS $args{repl_table} "
+                     . "failed, but the table already exists.  This "
+                     . "is harmless unless the slaves don't have the "
+                     . "table. $EVAL_ERROR";
          }
          else {
-         die "--replicate table $repl_table does not exist; "
-            . "read the documentation or use --create-replicate-table "
-            . "to create it.\n";
+            die $EVAL_ERROR;
          }
       }
-   else {
-      PTDEBUG && _d('--replicate table', $repl_table, 'already exists');
+   }
+
    # Check it again but this time check the privs.
    my $have_tbl_privs = $tp->check_table(
       dbh       => $dbh,
@@ -8186,7 +8218,6 @@ sub check_repl_table {
    );
    die "User does not have all privileges on --replicate table "
       . "$repl_table.\n" unless $have_tbl_privs;
-   }
 
    # Check and wait for the repl table to appear on all slaves.
    # https://bugs.launchpad.net/percona-toolkit/+bug/1008778
@@ -8327,7 +8358,7 @@ sub create_repl_table {
    my ($dbh, $repl_table, $o) = @args{@required_args};
    PTDEBUG && _d('Creating --replicate table', $repl_table); 
    my $sql = $o->read_para_after(__FILE__, qr/MAGIC_create_replicate/);
-   $sql =~ s/CREATE TABLE checksums/CREATE TABLE $repl_table/;
+   $sql =~ s/CREATE TABLE checksums/CREATE TABLE IF NOT EXISTS $repl_table/;
    $sql =~ s/;$//;
    PTDEBUG && _d($dbh, $sql);
    eval {

t/pt-table-checksum/privs.t

@@ -41,9 +41,6 @@ elsif ( !$slave1_dbh ) {
 elsif ( !@{$master_dbh->selectall_arrayref("show databases like 'sakila'")} ) {
    plan skip_all => 'sakila database is not loaded';
 }
-else {
-   plan tests => 3;
-}
 
 # The sandbox servers run with lock_wait_timeout=3 and it's not dynamic
 # so we need to specify --lock-wait-timeout=3 else the tool will die.
@@ -54,6 +51,49 @@ my $output;
 my $exit_status;
 my $sample  = "t/pt-table-checksum/samples/";
 
+# ############################################################################
+# Should always create schema and tables with IF NOT EXISTS
+# https://bugs.launchpad.net/percona-toolkit/+bug/950294
+# ############################################################################
+
+$sb->wipe_clean($master_dbh);
+diag(`/tmp/12345/use -u root < $trunk/t/lib/samples/ro-checksum-user.sql 2>/dev/null`);
+PerconaTest::wait_for_table($slave1_dbh, "mysql.tables_priv", "user='ro_checksum_user'");
+
+($output, $exit_status) = full_output(
+   sub { pt_table_checksum::main(@args,
+      "$master_dsn,u=ro_checksum_user,p=msandbox",
+      qw(--recursion-method none)
+   ) },
+);
+
+isnt($exit_status, 0, "");
+like($output,
+   qr/\Q--replicate database percona does not exist and it cannot be created automatically/,
+   "fails if the percona db doesn't exist and the user can't create it",
+);
+
+($output, $exit_status) = full_output(
+   sub { pt_table_checksum::main(@args,
+      "$master_dsn,u=ro_checksum_user,p=msandbox",
+      qw(--recursion-method none --no-create-replicate-table)
+   ) },
+);
+
+like($output,
+   qr/\Q--replicate database percona does not exist and --no-create-replicate-table was/,
+   "fails if the percona db doesn't exist and --no-create-replicate-table",
+);
+
+diag(`/tmp/12345/use -u root -e "drop user 'ro_checksum_user'\@'%'"`);
+wait_until(
+   sub {
+      my $rows=$slave2_dbh->selectall_arrayref("SELECT user FROM mysql.user");
+      return !grep { ($_->[0] || '') ne 'ro_checksum_user' } @$rows;
+   }
+);
+$sb->wipe_clean($master_dbh);
+
 # ############################################################################
 # --recursion-method=none to avoid SHOW SLAVE HOSTS
 # https://bugs.launchpad.net/percona-toolkit/+bug/987694
@@ -64,7 +104,7 @@ pt_table_checksum::main(@args,
    "$master_dsn,u=msandbox,p=msandbox",
    qw(-t sakila.country --quiet --quiet));
 
-diag(`/tmp/12345/use -u root < $trunk/t/lib/samples/ro-checksum-user.sql`);
+diag(`/tmp/12345/use -u root < $trunk/t/lib/samples/ro-checksum-user.sql 2>/dev/null`);
 PerconaTest::wait_for_table($slave1_dbh, "mysql.tables_priv", "user='ro_checksum_user'");
 
 $output = output(
@@ -90,6 +130,20 @@ like(
    "Read-only user (bug 987694): checksummed rows"
 );
 
+diag(qx{/tmp/12345/use -u root -e 'DROP TABLE `percona`.`checksums`'});
+
+($output, $exit_status) = full_output(
+   sub { pt_table_checksum::main(@args,
+      "$master_dsn,u=ro_checksum_user,p=msandbox",
+      qw(--recursion-method none --no-create-replicate-table)
+   ) },
+);
+
+like($output,
+   qr/\Q--replicate table `percona`.`checksums` does not exist and --no/,
+   "fails if the checksums db doesn't exist and --no-create-replicate-table"
+);
+
 diag(`/tmp/12345/use -u root -e "drop user 'ro_checksum_user'\@'%'"`);
 wait_until(
    sub {
@@ -103,4 +157,5 @@ wait_until(
 # #############################################################################
 $sb->wipe_clean($master_dbh);
 ok($sb->ok(), "Sandbox servers") or BAIL_OUT(__FILE__ . " broke the sandbox");
-exit;
+
+done_testing;