Merged fix-1034717-divison-by-zero-base-1

bin/pt-table-sync

@@ -3978,6 +3978,12 @@ sub _chunk_char {
    }
    PTDEBUG && _d("Base", $base, "chars:", @chars);
 
+   die "Cannot chunk table $db_tbl using the character column "
+     . "$chunk_col, most likely because all values start with the "
+     . "same character.  This table must be synced separately by "
+     . "specifying a list of --algorithms without the Chunk algorithm"
+      if $base == 1;
+
 
    $sql = "SELECT MAX(LENGTH($qchunk_col)) FROM $db_tbl "
         . ($args{where} ? "WHERE $args{where} " : "") 
@@ -11192,6 +11198,10 @@ primary key columns and a checksum are sent over the network, not the entire
 row.  If a row is found to be different, the entire row will be fetched, but not
 before.
 
+Note that this algorithm will not work if chunking a char column where all
+the values start with the same character. In that case, the tool will exit
+and suggest picking a different algorithm.
+
 =item Nibble
 
 Finds an index and ascends the index in fixed-size nibbles of L<"--chunk-size">

lib/TableChunker.pm

@@ -627,6 +627,13 @@ sub _chunk_char {
    }
    PTDEBUG && _d("Base", $base, "chars:", @chars);
 
+   # See https://bugs.launchpad.net/percona-toolkit/+bug/1034717
+   die "Cannot chunk table $db_tbl using the character column "
+     . "$chunk_col, most likely because all values start with the "
+     . "same character.  This table must be synced separately by "
+     . "specifying a list of --algorithms without the Chunk algorithm"
+      if $base == 1;
+
    # Now we begin calculating how to chunk the char column.  This is
    # completely different from _chunk_numeric because we're not dealing
    # with the values to chunk directly (the characters) but rather a map.

t/lib/TableChunker.t

@@ -25,9 +25,6 @@ my $dbh = $sb->get_dbh_for('master');
 if ( !$dbh ) {
    plan skip_all => 'Cannot connect to sandbox master';
 }
-else {
-   plan tests => 94;
-}
 
 $sb->create_dbs($dbh, ['test']);
 
@@ -1358,11 +1355,10 @@ is_deeply(
    "Caclulate chunks for `key` col (bug 967451)"
 );
 
-# #############################################################################
+# ############################################################################# ">
 # base_count fails on n = 1000, base = 10
 # https://bugs.launchpad.net/percona-toolkit/+bug/1028710
 # #############################################################################
-
 my $res = TableChunker->base_count(
    count_to => 1000,
    base     => 10,
@@ -1375,9 +1371,43 @@ is(
    "base_count's floor()s account for floating point arithmetics",
 );
 
+# #############################################################################
+# Bug 1034717: Divison by zero error when all columns tsart with the same char
+# https://bugs.launchpad.net/percona-toolkit/+bug/1034717
+# #############################################################################
+$sb->load_file('master', "t/lib/samples/bug_1034717.sql", 'test');
+$t = $tp->parse( $tp->get_create_table($dbh, 'bug_1034717', 'table1') );
+
+%params = $c->get_range_statistics(
+   dbh        => $dbh,
+   db         => 'bug_1034717',
+   tbl        => 'table1',
+   chunk_col  => 'field1',
+   tbl_struct => $t,
+);
+
+local $EVAL_ERROR;
+eval {
+   $c->calculate_chunks(
+      dbh        => $dbh,
+      db         => 'bug_1034717',
+      tbl        => 'table1',
+      tbl_struct => $t,
+      chunk_col  => 'field1',
+      chunk_size => '50',
+      %params,
+   );
+};
+like(
+   $EVAL_ERROR,
+   qr/^\QCannot chunk table `bug_1034717`.`table1` using the character column field1, most likely because all values start with the /,
+   "Bug 1034717: Catches the base == 1 case and dies"
+);
+
 # #############################################################################
 # Done.
 # #############################################################################
 $sb->wipe_clean($dbh);
 ok($sb->ok(), "Sandbox servers") or BAIL_OUT(__FILE__ . " broke the sandbox");
-exit;
+
+done_testing;