Adding indexes on empty table is slow with large innodb_sort_buffer_size.

Hi,

I am creating a table without indexes and then adding indexes to the table. The table definition is the following:

CREATE TABLE `test_wo_keys` (
`f01` int AUTO_INCREMENT,
`f02` bigint, `f03` bigint, `f04` enum('a','b'),
`f05` date, `f06` int, `f07` int, `f08` double, `f09` int,
`f10` bigint, `f11` double, `f12` enum('a','b','c','d','e'),
`f13` int, `f14` int, `f15` varchar(255), `f16` int, `f17` int, `f18` int,
`f19` double, `f20` double, `f21` double, `f22` double, `f23` double, `f24` tinyint,
`f25` double, `f26` double, `f27` double, `f28` double, `f29` int unsigned,
`f30` int unsigned, `f31` bigint, `f32` int unsigned, `f33` bigint,
`f34` int unsigned, `f35` int unsigned,
PRIMARY KEY `f01` (`f01`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

and the indexes are the following:

ALTER TABLE test_wo_keys
ADD KEY `f06` (`f06`), ADD KEY `f05` (`f05`), ADD KEY `f04` (`f04`), ADD KEY `f23` (`f23`),
ADD KEY `f10` (`f10`), ADD KEY `f11` (`f11`), ADD KEY `f09` (`f09`), ADD KEY `f22` (`f22`),
ADD KEY `f21` (`f21`), ADD KEY `f07` (`f07`), ADD KEY `f08` (`f08`), ADD KEY `f18` (`f18`),
ADD KEY `f19` (`f19`), ADD KEY `f20` (`f20`), ADD KEY `f29` (`f29`,`f31`,`f33`),
ADD KEY `f35` (`f35`), ADD KEY `f25` (`f25`), ADD KEY `f26` (`f26`),
ADD KEY `f27` (`f27`), ADD KEY `f28` (`f28`);

When I create the table and add the indexes without previously inserting data in the table (empty table), it works as expected with "innodb_sort_buffer_size = 1M" but it is slow with "innodb_sort_buffer_size = 64M":

> SHOW GLOBAL VARIABLES LIKE 'innodb_sort_buffer_size';
--------------------------------+

--------------------------------+

--------------------------------+
1 row in set (0.00 sec)

> CREATE TABLE `test_wo_keys` (
...
Query OK, 0 rows affected (0.00 sec)

> ALTER TABLE test_wo_keys
...
Query OK, 0 rows affected (0.07 sec)
Records: 0 Duplicates: 0 Warnings: 0

> SHOW GLOBAL VARIABLES LIKE 'innodb_sort_buffer_size';
---------------------------------+

---------------------------------+

---------------------------------+
1 row in set (0.00 sec)

> CREATE TABLE `test_wo_keys` (
...
Query OK, 0 rows affected (0.00 sec)

> ALTER TABLE test_wo_keys
...
Query OK, 0 rows affected (7.43 sec)
Records: 0 Duplicates: 0 Warnings: 0

This is unexpected and should probably be optimized.

Thanks,

JFG