INDEX(o_orderdate, o_cust_key, o_orderkey)
Would probably help a bunch.
I assume you have indexes (PKs?) on c_custkey, l_order_key, n_nationkey.
Please provide SHOW CREATE TABLE and SHOW STATUS TABLE.
-----Original Message-----
From: Hal?sz S?ndor [mailto:hsv@stripped]
Sent: Tuesday, April 10, 2012 5:20 PM
To: mysql@stripped
Subject: Re: forcing mysql to use batched key access (BKA) optimization for joins
>>>> 2012/04/10 15:58 -0400, Stephen Tu >>>>
select
c_custkey,
c_name,
sum(l_extendedprice * (100 - l_discount)) as revenue,
c_acctbal,
n_name,
c_address,
c_phone,
c_comment
from CUSTOMER_INT, ORDERS_INT, LINEITEM_INT, NATION_INT
where
c_custkey = o_custkey
and l_orderkey = o_orderkey
and o_orderdate >= date '1994-08-01'
and o_orderdate < date '1994-08-01' + interval '3' month
and l_returnflag = 'R' and c_nationkey = n_nationkey
group by c_custkey, c_name, c_acctbal, c_phone, n_name,
c_address, c_comment
order by revenue desc limit 20
<<<<<<<<
I understand that MySQL works better if inner joining explicitly is stated, not implicitly
as you have it.
What are your keys, indices? Going by that which I have read & heard, you want every
field named after this query s 'where' an index, if not key--and, of course, your every
field named '...key' is a key, right?
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