Merge pull request #996 from utdrmac/pt-dup-index-invis

Add invisible option to pt-duplicate-key-checker

bin/pt-duplicate-key-checker

@@ -5301,12 +5301,19 @@ sub print_duplicate_key {
 
    if ( $o->get('sql') ) {
       if ( $dupe->{dupe_type} ne 'clustered' ) {
-         print "# To remove this duplicate "
-            . ($args{is_fk} ? 'foreign key' : 'index')
-            . ", execute:\n"
-            . 'ALTER TABLE ' . $q->quote($db, $tbl)
-            . ($args{is_fk} ? ' DROP FOREIGN KEY ' : ' DROP INDEX ')
-            . "`$dupe->{key}`;\n";
+         if ( $o->get('invisible') && !$args{is_fk} ) {
+            print "# To make this index invisible, execute:\n"
+               . 'ALTER TABLE ' . $q->quote($db, $tbl)
+               . " ALTER INDEX `$dupe->{key}` INVISIBLE;\n";
+         }
+         else {
+            print "# To remove this duplicate "
+               . ($args{is_fk} ? 'foreign key' : 'index')
+               . ", execute:\n"
+               . 'ALTER TABLE ' . $q->quote($db, $tbl)
+               . ($args{is_fk} ? ' DROP FOREIGN KEY ' : ' DROP INDEX ')
+               . "`$dupe->{key}`;\n";
+         }
       }
       else {
          # Suggest shortening clustered dupes instead of
@@ -5566,6 +5573,19 @@ type: Hash
 Ignore this comma-separated list of tables.  Table names may be qualified with
 the database name.
 
+=item --invisible
+
+The output SQL will make the index INVISIBLE, instead of dropping it.
+
+An invisible index cannot be considered by the query optimizer, but is still
+maintained when writes happen to the table. To make the index usable by the
+optimizer, execute ALTER INDEX .. VISIBLE
+
+While dropping an index is a fast, background operation, adding indexes is
+a slow, CPU, and disk IO intensive operation. If you discover that an index
+was made invisible incorrectly, it becomes a NOOP (no-operation) to make the index visible again,
+compared to completely re-adding the index.
+
 =item --key-types
 
 type: string; default: fk

bin/pt-online-schema-change

@@ -8879,7 +8879,7 @@ sub main {
       # it's a hack, like ignoring a problem instead of fixing it somehow. We
       # should take a look at the things that get printed in a "normal"
       # non-quiet run, and "if !quiet" them, and then do some kind of Logger.pm
-      # or Messager.pm module for a future release.
+      # or Message.pm module for a future release.
       close STDOUT;
       open  STDOUT, '>', '/dev/null'
          or warn "Cannot reopen STDOUT to /dev/null: $OS_ERROR";

t/pt-duplicate-key-checker/basics.t

@@ -80,6 +80,15 @@ ok(
    '--nosql'
 );
 
+ok(
+   no_diff(
+      sub { pt_duplicate_key_checker::main(@args, qw(-d test --invisible)) },
+      "$sample/basic_invisible.txt",
+      transform_sample => $transform_int
+    ),
+    '--invisible'
+);
+
 ok(
    no_diff(
       sub { pt_duplicate_key_checker::main(@args, qw(-d test --nosummary)) },

t/pt-duplicate-key-checker/samples/basic_invisible.txt

@@ -0,0 +1,21 @@
+# ########################################################################
+# test.dupe_key                                                           
+# ########################################################################
+
+# a is a left-prefix of a_2
+# Key definitions:
+#   KEY `a` (`a`),
+#   KEY `a_2` (`a`,`b`)
+# Column types:
+#	  `a` int(11) default null
+#	  `b` int(11) default null
+# To make this index invisible, execute:
+ALTER TABLE `test`.`dupe_key` ALTER INDEX `a` INVISIBLE;
+
+# ########################################################################
+# Summary of indexes                                                      
+# ########################################################################
+
+# Size Duplicate Indexes   0
+# Total Duplicate Indexes  1
+# Total Indexes            2