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, 67 insertions, 6 deletions

diff --git a/sql/sql_table.cc b/sql/sql_table.cc
index 256b9281e9f..f82dd627101 100644
--- a/sql/sql_table.cc
+++ b/sql/sql_table.cc
@@ -34,11 +34,12 @@ const char *primary_key_name="PRIMARY";
 static bool check_if_keyname_exists(const char *name,KEY *start, KEY *end);
 static char *make_unique_key_name(const char *field_name,KEY *start,KEY *end);
 static int copy_data_between_tables(TABLE *from,TABLE *to,
-				    List<create_field> &create,
-				    enum enum_duplicates handle_duplicates,
+                                    List<create_field> &create,
+                                    enum enum_duplicates handle_duplicates,
                                     bool ignore,
-				    uint order_num, ORDER *order,
-				    ha_rows *copied,ha_rows *deleted);
+                                    uint order_num, ORDER *order,
+                                    ha_rows *copied, ha_rows *deleted,
+                                    enum enum_enable_or_disable keys_onoff);
 
 
 /*
@@ -2837,6 +2838,54 @@ int mysql_drop_indexes(THD *thd, TABLE_LIST *table_list,
 
 
 /*
+  Manages enabling/disabling of indexes for ALTER TABLE
+
+  SYNOPSIS
+    alter_table_manage_keys()
+      table                  Target table
+      indexes_were_disabled  Whether the indexes of the from table
+                             were disabled
+      keys_onoff             ENABLE | DISABLE | LEAVE_AS_IS
+
+  RETURN VALUES
+    FALSE  OK
+    TRUE   Error
+*/
+
+static
+bool alter_table_manage_keys(TABLE *table, int indexes_were_disabled,
+                             enum enum_enable_or_disable keys_onoff)
+{
+  int error= 0;
+  DBUG_ENTER("alter_table_manage_keys");
+  DBUG_PRINT("enter", ("table=%p were_disabled=%d on_off=%d",
+             table, indexes_were_disabled, keys_onoff));
+
+  switch (keys_onoff) {
+  case ENABLE:
+    error= table->file->enable_indexes(HA_KEY_SWITCH_NONUNIQ_SAVE);
+    break;
+  case LEAVE_AS_IS:
+    if (!indexes_were_disabled)
+      break;
+    /* fall-through: disabled indexes */
+  case DISABLE:
+    error= table->file->disable_indexes(HA_KEY_SWITCH_NONUNIQ_SAVE);
+  }
+
+  if (error == HA_ERR_WRONG_COMMAND)
+  {
+    push_warning_printf(current_thd, MYSQL_ERROR::WARN_LEVEL_NOTE,
+                        ER_ILLEGAL_HA, ER(ER_ILLEGAL_HA), table->table_name);
+    error= 0;
+  } else if (error)
+    table->file->print_error(error, MYF(0));
+
+  DBUG_RETURN(error);
+}
+
+
+/*
   Alter table
 */
 
@@ -3375,7 +3424,14 @@ int mysql_alter_table(THD *thd,char *new_db, char *new_name,
   if (!new_table->is_view)
     error=copy_data_between_tables(table,new_table,create_list,
 				   handle_duplicates, ignore,
-				   order_num, order, &copied, &deleted);
+				   order_num, order, &copied, &deleted,
+                                   alter_info->keys_onoff);
+  /*
+    No need to have call to alter_table_manage_keys() in the else because
+    in 4.1 we always copy data, except for views. In 5.0 it could happen
+    that no data is copied and only frm is modified. Then we have to handle
+    alter_info->keys_onoff outside of copy_data_between_tables
+  */
   thd->last_insert_id=next_insert_id;		// Needed for correct log
   thd->count_cuted_fields= CHECK_FIELD_IGNORE;
 
@@ -3598,7 +3654,8 @@ copy_data_between_tables(TABLE *from,TABLE *to,
                          bool ignore,
 			 uint order_num, ORDER *order,
 			 ha_rows *copied,
-			 ha_rows *deleted)
+			 ha_rows *deleted,
+                         enum enum_enable_or_disable keys_onoff)
 {
   int error;
   Copy_field *copy,*copy_end;
@@ -3630,6 +3687,10 @@ copy_data_between_tables(TABLE *from,TABLE *to,
 
   if (to->file->external_lock(thd, F_WRLCK))
     DBUG_RETURN(-1);
+
+  /* We need external lock before we can disable/enable keys */
+  alter_table_manage_keys(to, from->file->indexes_are_disabled(), keys_onoff);
+
   from->file->info(HA_STATUS_VARIABLE);
   to->file->start_bulk_insert(from->file->records);