I’ve a table like so:
fro
int(11),
nid
int(11)
Primary key is fro, nid.
I have an index on fro and an index on nid
Storage engine is innodb; I’ve 3GB dedicated to innodb_buffer_pool_size.
These two queries are incredibly fast:
select nid from user_network where fro=506017534;
2 rows in set (0.00 sec)
select * from user_network where nid in (50431654, 67108872);
14590 rows in set (0.05 sec)
This query is unjustifiably slow.
select * from user_network where nid in (select nid from user_network where fro
=506017534);
14590 rows in set (8.86 sec)
What’s going on? I’m beginning to think something is wrong with my disk…