mysql - alternative / efficient / optimized query -

i want alternative / efficient / optimized query following query:

table:

create table `bartco_web_vms_studio`.`table_name` (       `index` int( 10 ) not null auto_increment ,       `id1` int( 10 ) not null default '0',       `id2` varchar( 10 ) not null,       `f3` tinyint( 4 ) not null default '0',       primary key ( `index` ) ) engine = myisam ; 

composite index:

create index id1_id2 on tablename (id1, id2); 

number of rows = 7891

update query:

update table_name  set f3=1  id1=1 , id2='a'     or id1=2 , id2='b'    or id1=3 , id2='c' 

basically have update field's value based on 2 fields (id1, id2) values. these 2 fields can in more 1 pair.

output explain select f3 table_name ...:

id -> 1, select type -> simple, table -> table_name, type -> range, possible_keys -> id1_id2, key -> id1_id2, key_len -> 261, ref -> null, rows -> 2, -> using 

thanks lot help

regards

composite index id1 + id2 , query

where (id1, id2) in ((1, 'a'), (2, 'b'), (3, 'c')) 

should help

also, when you're testing - add more rows table.

since you're selecting 3 rows of 9 - mysql can decide never use index @ all.

upd:

if nothing our answers - can split query 3:

select * table id1 .. , id2 .. union select * table id1 .. , id2 .. ...