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List:       mysql
Subject:    RE: forcing mysql to use batched key access (BKA) optimization  for joins
From:       Rick James <rjames () yahoo-inc ! com>
Date:       2012-04-17 18:57:03
Message-ID: 2E7DD7ADE53B044C8C8BCD9C5829E1EB1485A7D534 () SP2-EX07VS01 ! ds ! corp ! yahoo ! com
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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@tbbs.net] 
Sent: Tuesday, April 10, 2012 5:20 PM
To: mysql@lists.mysql.com
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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