The old cliche SIZE MATTERS applies here without a doubt.
Smaller keys would load into a table faster that with biggers (This becomes even more evident with InnoDB). The bigger the columns in the index, the fewer the keys would be residing in BTREE pages. Thus, you get taller BTREE trees. Even a BTREE height of 3 or more, which is bad for a small table, would be the result of having large columns. The same would apply to the name (up to 150 characters) and category (up to 100 characters) fields. Making all columns CHAR instead of VARCHAR would increase SELECT performance, but the significant increase of diskspace + BTREE node management would throw SELECT performance under the bus as the table grows.
Looking at all of your keys I can see this table being extermely lopsided in index size verses table size.
Please run this query
SELECT data_lenth,index_length
FROM information_schema.tables
WHERE table_name = 'acl_action';
You will see the combined sum of all index pages being as large or larger than the table. From a physical standpoint, the file acl_actions.MYI will be bigger that acl_actions.MYD.
Here is where random I/O would come into play: Notice your index idx_aclaction_id_del
Notice that you have it defined as
KEY `idx_aclaction_id_del` (`id`,`deleted`),
If you ever decide to query for deleted records, you will get an full index scan because of the order of trhe columns in this index.
KEY `idx_aclaction_del_id` (`deleted`,`id`),
That way all deleted keys are grouped together. Likewise, all non-deleted rows are grouped together.
Try altering the table design like this
CREATE TABLE `acl_actions` (
`id` INT UNSIGNED NOT NULL AUTO_INCREMENT,
`guid` char(36) NOT NULL,
`date_entered` datetime NOT NULL,
`name` varchar(150) default NULL,
........
`category` varchar(100) default NULL,
`deleted` tinyint(1) default '0',
PRIMARY KEY (`id`),
UNQIUE KEY (`guid`),
KEY `idx_aclaction_id_del` (`deleted`,`id`),
KEY `idx_category_name` (`category`,`name`)
) ENGINE=MyISAM DEFAULT CHARSET=utf8;
You should run the following query
SELECT name,categrory FROM acl_actions PROCEDURE ANALYSE();
This will recommend the correct sizes for those columns with the given dataset.
Best Answer
Depending on the type of backup, that can indeed happen. It's therefore recommended to disable foreign key checks before the restore, e.g. with
and re-enabling them afterwards with
This has another advantage: MySQL won't check the foreign key for every single imported record, but for all records at once. This will speed up your restore.
See Disabling foreign key checks on the command line on Stack Overflow.