How to enhance response time on select?

Question

I'm using ibatis/mySql in my struts application and apparently the response time to receive data (select) is quite long.
I'm referring to a select statement to receive data from 5 diff tables (~6 column each). there are 500 objects (Cars) and it takes around 63 seconds (my computer has 2GB Ram).
can someone advise how to enhance the response time.
thanks

Answer 1

yes, they all have primary keys and indexes.
Do you do the JOIN in the database or are yougetting a ResultSet and then iterating over it to
SELECT the rest? (This will kill you with network
traffic.)
yes I'm using the select with no join.
I'm using abator to auto-generate the sql statements
and therefore I loop on every car'd id and get my
releven info. so basically it's all select after
select and integrate them in the car object. That's the reason then: If your outer select returns N rows, you're doing N network roundtrips to get the rest of the data. It's a certain performance killer.
is there major diff between reading one by one oever
reading everything in one go? meaning right now i do
this:
get list of all car_idNetwork roundtrip #1
iterate through db with car_id and construct a CAR object...Which means one round trip per row. You're dead in the water here, no matter how you optimize the database.
add object to LinkedList move to the next car...Rewrite that query and bring all the data back in one network roundtrip. You'll notice an immediate improvement.
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