Compare lc(index) everywhere.

bin/pt-table-checksum

@@ -3778,7 +3778,7 @@ sub set_nibble_number {
 
 sub nibble_index {
    my ($self) = @_;
-   return $self->{index};
+   return lc($self->{index});
 }
 
 sub statements {
@@ -6399,12 +6399,19 @@ sub main {
             sth  => $sth->{explain_upper_boundary},
             vals => [ @{$boundary->{lower}}, $nibble_iter->chunk_size() ],
          );
-         if ( ($expl->{key} || '') ne $nibble_iter->nibble_index() ) {
+         if ( lc($expl->{key} || '') ne $nibble_iter->nibble_index() ) {
             PTDEBUG && _d('Cannot nibble next chunk, aborting table');
             if ( $o->get('quiet') < 2 ) {
-               warn ts("Aborting $tbl->{db}.$tbl->{tbl} because "
+               my $msg
+                  = "Aborting table $tbl->{db}.$tbl->{tbl} at chunk "
                   . ($nibble_iter->nibble_number() + 1)
-                  . " cannot be nibbled safely.\n");
+                  . " because it is not safe to chunk.  Chunking should "
+                  . "use the "
+                  . ($nibble_iter->nibble_index() || '?')
+                  . " index, but MySQL EXPLAIN reports that "
+                  . ($expl->{key} ? "the $expl->{key}" : "no")
+                  . " index will be used.\n";
+               warn ts($msg);
             }
             $tbl->{checksum_results}->{errors}++;
             return 0; # stop nibbling table
@@ -6460,7 +6467,7 @@ sub main {
                :          0;
 
             # Ensure that MySQL is using the chunk index.
-            if ( ($expl->{key} || '') ne $nibble_iter->nibble_index() ) {
+            if ( lc($expl->{key} || '') ne $nibble_iter->nibble_index() ) {
                PTDEBUG && _d('Chunk', $args{nibbleno}, 'of table',
                   "$tbl->{db}.$tbl->{tbl} not using chunk index, skipping");
                return 0;  # next boundary
@@ -7260,15 +7267,13 @@ sub have_more_chunks {
    # The previous chunk index must match the current chunk index,
    # else we don't know what to do.
    my $chunk_index = $nibble_iter->nibble_index() || '';
-   if (    ($last_chunk->{chunk_index}   || '')
+   if (lc($last_chunk->{chunk_index}   || '') ne $chunk_index) {
-        ne ($nibble_iter->nibble_index() || '') ) {
       warn ts("Cannot resume from table $tbl->{db}.$tbl->{tbl} chunk "
          . "$last_chunk->{chunk} because the chunk indexes are different: "
          . ($last_chunk->{chunk_index} ? $last_chunk->{chunk_index} 
                                        : "no index")
          . " was used originally but "
-         . ($nibble_iter->nibble_index() ? $nibble_iter->nibble_index()
+         . ($chunk_index ? $chunk_index : "no index")
-                                         : "no index")
          . " is used now.  If the table has not changed significantly, "
          . "this may be caused by running the tool with different command "
          . "line options.  This table will be skipped and checksumming "

lib/NibbleIterator.pm

@@ -347,7 +347,7 @@ sub set_nibble_number {
 
 sub nibble_index {
    my ($self) = @_;
-   return $self->{index};
+   return lc($self->{index});
 }
 
 sub statements {

t/pt-table-checksum/chunk_index.t

@@ -25,7 +25,7 @@ if ( !$dbh ) {
    plan skip_all => 'Cannot connect to sandbox master';
 }
 else {
-   plan tests => 6;
+   plan tests => 10;
 }
 
 # The sandbox servers run with lock_wait_timeout=3 and it's not dynamic
@@ -104,6 +104,43 @@ ok(
    "Explicit --chunk-index overrides MySQL's index for --where"
 );
 
+# #############################################################################
+# Bug 925855: pt-table-checksum index check is case-sensitive
+# #############################################################################
+$sb->load_file('master', "t/pt-table-checksum/samples/all-uc-table.sql");
+my $exit_status = 0;
+$output = output(sub {
+   $exit_status = pt_table_checksum::main(
+      $master_dsn, '--max-load', '',
+      qw(--lock-wait-timeout 3 --chunk-size 5 -t ALL_UC.T)
+   ) },
+   stderr => 1,
+);
+
+is(
+   $exit_status,
+   0,
+   "Zero exit status (bug 925855)"
+);
+
+is(
+   PerconaTest::count_checksum_results($output, 'skipped'),
+   0,
+   "0 skipped (bug 925855)"
+);
+
+is(
+   PerconaTest::count_checksum_results($output, 'errors'),
+   0,
+   "0 errors (bug 925855)"
+);
+
+is(
+   PerconaTest::count_checksum_results($output, 'rows'),
+   13,
+   "14 rows checksummed (bug 925855)"
+);
+
 # #############################################################################
 # Done.
 # #############################################################################

t/pt-table-checksum/samples/all-uc-table.sql

@@ -0,0 +1,22 @@
+DROP DATABASE IF EXISTS ALL_UC;
+CREATE DATABASE ALL_UC;
+USE ALL_UC;
+CREATE TABLE T (
+  ID  INT NOT NULL,
+  C   VARCHAR(8) NOT NULL,
+  UNIQUE INDEX (ID)
+) ENGINE=INNODB;
+INSERT INTO T VALUES
+  (1, 'AAA'),
+  (2, 'BBB'),
+  (3, 'CCC'),
+  (4, 'DDD'),  
+  (5, 'EEE'),
+  (6, 'FFF'),
+  (7, 'GGG'),
+  (8, 'HHH'),
+  (9, 'III'),
+  (10,'JJJ'),
+  (11,'KKK'),  
+  (12,'LLL'),
+  (13,'MMM');

t/pt-table-checksum/samples/no-recheck.txt

@@ -1,10 +1,10 @@
 Differences on h=127.0.0.1,P=12346
 TABLE CHUNK CNT_DIFF CRC_DIFF CHUNK_INDEX LOWER_BOUNDARY UPPER_BOUNDARY
-sakila.city 1 0 1 PRIMARY 1 100
+sakila.city 1 0 1 primary 1 100
-sakila.city 6 0 1 PRIMARY 501 600
+sakila.city 6 0 1 primary 501 600
 
 Differences on h=127.0.0.1,P=12347
 TABLE CHUNK CNT_DIFF CRC_DIFF CHUNK_INDEX LOWER_BOUNDARY UPPER_BOUNDARY
-sakila.city 1 0 1 PRIMARY 1 100
+sakila.city 1 0 1 primary 1 100
-sakila.city 6 0 1 PRIMARY 501 600
+sakila.city 6 0 1 primary 501 600