I have read articles about
FORCE index, but how can I force MySQL to
IGNORE ALL indexes?
SELECT * FROM tbl IGNORE INDEX(*), but I was not successful.
As for why I (and others) need to do this: For example, I needed to summarize referers statistics by tld like this:
SELECT count(*) as c, SUBSTRING ( domain_name, LENGTH(domain_name) - LOCATE('.', REVERSE(domain_name)) + 2 ) as tld FROM `domains_import` IGNORE INDEX(domain_name) GROUP BY tld ORDER BY c desc LIMIT 100
...but I always have to look at what indexes are defined or determine what index will be used via Explain. It would be very handy to simply write
IGNORE INDEX ALL and simply not care.
Does anyone know the syntax or a hack? (Tens of lines via MySQL definition tables are really not a shortcut).
Added from chat discussion:
no index = 148.5 secs
with index = 180 secs and still running with Sending data The SSD array is so powerful, that you almost no care about data cache...
Definition for benchmark:
CREATE TABLE IF NOT EXISTS `domains_import` ( `domain_id` bigint(20) unsigned NOT NULL, `domain_name` varchar(253) CHARACTER SET ascii COLLATE ascii_bin NOT NULL ) ENGINE=InnoDB DEFAULT CHARSET=utf8; ALTER TABLE `domains_import` ADD PRIMARY KEY (`domain_id`), ADD UNIQUE KEY `domain_name` (`domain_name`); ALTER TABLE `domains_import` MODIFY `domain_id` bigint(20) unsigned NOT NULL AUTO_INCREMENT;
InnoDB, the test with index (no USE INDEX() or similar) is still running, 250 secs, I just killed it.