Fix for bug#24395:

ALTER TABLE DISABLE KEYS doesn't work when modifying the table
  
ENABLE|DISABLE KEYS combined with another ALTER TABLE option, different
than RENAME TO did nothing. Also, if the table had disabled keys
and was ALTER-ed then the end table was with enabled keys.
  
Fixed by checking whether the table had disabled keys and enabling them
in the copied table.


myisam/mi_open.c:
  Extend mi_indexes_are_disabled to implement return value
  2 - Non-unique indexes are disabled
mysql-test/r/alter_table.result:
  update result
mysql-test/t/alter_table.test:
  update test
sql/sql_table.cc:
  When ENABLE|DISABLE index is combined with another option
  different than RENAME TO, we should ENABLE|DISABLE the keys of
  the modified table. Also when modifying we should preserve the
  previous state of the indices.
  (This problem exists in 5.0 and 5.1 but since the codebase has
  diverged, this fix won't automerge, but the fix will be quite
  similar).

1 files changed, 97 insertions, 0 deletions

diff --git a/mysql-test/t/alter_table.test b/mysql-test/t/alter_table.test
index eba456982c8..f4624eda053 100644
--- a/mysql-test/t/alter_table.test
+++ b/mysql-test/t/alter_table.test
@@ -362,6 +362,103 @@ alter table t1 add unique ( a(1) );
 drop table t1;
 
 #
+# Bug #24395: ALTER TABLE DISABLE KEYS doesn't work when modifying the table
+#
+# This problem happens if the data change is compatible.
+# Changing to the same type is compatible for example.
+#
+--disable_warnings
+drop table if exists t1;
+--enable_warnings
+create table t1 (a int, key(a));
+show indexes from t1;
+--echo "this used not to disable the index"
+alter table t1 modify a int, disable keys;
+show indexes from t1;
+
+alter table t1 enable keys;
+show indexes from t1;
+
+alter table t1 modify a bigint, disable keys;
+show indexes from t1;
+
+alter table t1 enable keys;
+show indexes from t1;
+
+alter table t1 add b char(10), disable keys;
+show indexes from t1;
+
+alter table t1 add c decimal(10,2), enable keys;
+show indexes from t1;
+
+--echo "this however did"
+alter table t1 disable keys;
+show indexes from t1;
+
+desc t1;
+
+alter table t1 add d decimal(15,5);
+--echo "The key should still be disabled"
+show indexes from t1;
+
+drop table t1;
+
+--echo "Now will test with one unique index"
+create table t1(a int, b char(10), unique(a));
+show indexes from t1;
+alter table t1 disable keys;
+show indexes from t1;
+alter table t1 enable keys;
+
+--echo "If no copy on noop change, this won't touch the data file"
+--echo "Unique index, no change"
+alter table t1 modify a int, disable keys;
+show indexes from t1;
+
+--echo "Change the type implying data copy"
+--echo "Unique index, no change"
+alter table t1 modify a bigint, disable keys;
+show indexes from t1;
+
+alter table t1 modify a bigint;
+show indexes from t1;
+
+alter table t1 modify a int;
+show indexes from t1;
+
+drop table t1;
+
+--echo "Now will test with one unique and one non-unique index"
+create table t1(a int, b char(10), unique(a), key(b));
+show indexes from t1;
+alter table t1 disable keys;
+show indexes from t1;
+alter table t1 enable keys;
+
+
+--echo "If no copy on noop change, this won't touch the data file"
+--echo "The non-unique index will be disabled"
+alter table t1 modify a int, disable keys;
+show indexes from t1;
+alter table t1 enable keys;
+show indexes from t1;
+
+--echo "Change the type implying data copy"
+--echo "The non-unique index will be disabled"
+alter table t1 modify a bigint, disable keys;
+show indexes from t1;
+
+--echo "Change again the type, but leave the indexes as_is"
+alter table t1 modify a int;
+show indexes from t1;
+--echo "Try the same. When data is no copied on similar tables, this is noop"
+alter table t1 modify a int;
+show indexes from t1;
+
+drop table t1;
+
+
+#
 # Bug#11493 - Alter table rename to default database does not work without
 #             db name qualifying
 #