mysql - Slow Updates for Single Records by Primary Key -

i using mysql 5.5.

i have innodb table definition follows:

create table `table1` (   `col1` int(11) not null auto_increment,   `col2` int(11) default null,   `col3` varchar(255) collate utf8_unicode_ci default null,   `col4` int(11) default null,   `col5` datetime default null,   `col6` tinyint(1) not null default '0',   `col7` datetime not null,   `col8` datetime not null,   `col9` int(11) default null,   `col10` tinyint(1) not null default '0',   `col11` tinyint(1) default '0',   primary key (`col1`),   unique key `index_table1_on_ci_ai_tn_sti` (`col2`,`col4`,`col3`,`col9`),   key `index_shipments_on_applicant_id` (`col4`),   key `index_shipments_on_shipment_type_id` (`col9`),   key `index_shipments_on_created_at` (`col7`),   key `idx_tracking_number` (`col3`) ) engine=innodb auto_increment=7634960 default charset=utf8 collate=utf8_unicode_ci; 

the issue updates. there 2m rows in table.

a typical update query :

update table1 set col6 = 1 col1 = 7634912; 

we have 5-10k qps on production server. these queries in "updating" state when looked @ through process list. innodb locks show there many rec not gap locks on index_table1_on_ci_ai_tn_sti. no transaction waiting lock.

my feeling unique index causing lag i'm not sure why. table have defined way using unique index.

i don't think unique key has impact (in case).

are setting datetime "1"? (please check other typos -- could make big difference.)

are trying 10k updates per second?

is innodb_buffer_pool_size bigger table, no bigger 70% of available ram?

what value of innodb_flush_log_at_trx_commit? 1 default , secure, slower 2.

can put bunch of updates single transaction? cut down transaction overhead.