Fix for bug #18153 "ALTER/OPTIMIZE/REPAIR on transactional tables corrupt

triggers".

Applying ALTER/OPTIMIZE/REPAIR TABLE statements to transactional table or to
table of any type on Windows caused disappearance of its triggers.
Bug was introduced in 5.0.19 by my fix for bug #13525 "Rename table does not
keep info of triggers" (see comment for sql_table.cc for more info).
.


mysql-test/r/trigger.result:
  Added test-case covering handling of triggers when one does ALTER TABLE which
  should move table to different database.
mysql-test/t/trigger.test:
  Added test-case covering handling of triggers when one does ALTER TABLE which
  should move table to different database.
sql/sql_table.cc:
  mysql_alter_table():
    Removal of strdup() which is no longer necessary allows us to preserve
    nice assumption that "(new_db != db || new_table != table_name) indicates
    that table will be renamed. So now we really can use this condition to
    avoid updating trigger definitions when table is not renamed.
    Note that we can't use (alter_info->flags & ALTER_RENAME) condition instead
    since it can be also true when we do "ALTER TABLE t1 RENAME TO t1".
sql/sql_trigger.cc:
  Table_triggers_list::change_table_name():
    Mentioned assumption that subject table is not renamed to itself in method
    description. Added DBUG_ASSERT() to catch wrong usage of this method.
mysql-test/r/trigger-trans.result:
  New BitKeeper file ``mysql-test/r/trigger-trans.result''
mysql-test/t/trigger-trans.test:
  New BitKeeper file ``mysql-test/t/trigger-trans.test''

1 files changed, 4 insertions, 0 deletions

diff --git a/sql/sql_trigger.cc b/sql/sql_trigger.cc
index b432961b7e6..41573324082 100644
--- a/sql/sql_trigger.cc
+++ b/sql/sql_trigger.cc
@@ -1373,6 +1373,7 @@ Table_triggers_list::change_table_name_in_trignames(const char *db_name,
     This method tries to leave trigger related files in consistent state,
     i.e. it either will complete successfully, or will fail leaving files
     in their initial state.
+    Also this method assumes that subject table is not renamed to itself.
 
   RETURN VALUE
     FALSE  Success
@@ -1394,6 +1395,9 @@ bool Table_triggers_list::change_table_name(THD *thd, const char *db,
 
   safe_mutex_assert_owner(&LOCK_open);
 
+  DBUG_ASSERT(my_strcasecmp(table_alias_charset, db, new_db) ||
+              my_strcasecmp(table_alias_charset, old_table, new_table));
+
   if (Table_triggers_list::check_n_load(thd, db, old_table, &table, TRUE))
   {
     result= 1;