Re: ** SQL tuning question
- From: A Joshi <ajoshi977@xxxxxxxxx>
- To: oracle-l@xxxxxxxxxxxxx
- Date: Mon, 1 Mar 2004 19:46:54 -0800 (PST)
Thank you all for your help : Mike, Dan Tow, Mark Bobak and Richard. The query
is better after using the use_nl(ro2 ro1 o c) hint and eliminating the
subquery.
Michael Thomas <mhthomas@xxxxxxxxx> wrote:
Hi,
The /*+ push_subq */ hint sometimes works if the
subquery is a small table. Good luck.
Regards,
Mike Thomas
--- A Joshi wrote:
> Hi,
> I have a query joining three tables similar to the
> following :
>
> select c.cust_name, o.order_number,
> ro1.related_order_number
> from order o, customer c, rel_orders ro1
> where c.cust_id = o.cust_id
> and c.cust_type = 'OV'
> and o.order_number = ro1.order_number
> and ro1.related_order_number in (select
> ro2.related_order_number from rel_orders ro2
> where
> ro2.order_number = :v_order_number)
>
> Tables order and customer are huge (millions) and
> rel_orders is very small (hundreads). I would like
> the optimizer to go to the small table first then
> get the order_number and go to orders table which
> has index on order_number and then go to cust table
> with cust_id(indexed). I tried the hint /*+ ordered
> (ro2 ro1 o c) */ but it does not help. I even tried
> to give the index hint for bigger tables but that
> does not help. it either does full table scan or
> index_full_scan. I tried several ways of writing the
> query but it does not help. I tried without the
> condition : and c.cust_type = 'OV'. No use.
> Please note that there can be more than one
> related_order_number for a order_number. Has someone
> encountered a similar case and can someone help.
> Thanks.
>
>
>
>
> ---------------------------------
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