Re: [PERFORM] Query tuning help

[CS DBA]

On 10/11/2011 12:02 PM, Pavel Stehule wrote:
Hello
please, send EXPLAIN ANALYZE output instead.

Regards

Pavel Stehule

2011/10/11 CS DBA<cs_...@consistentstate.com>:
Hi all ;

I'm trying to tune a difficult query.

I have 2 tables:
cust_acct (9million rows)
cust_orders (200,000 rows)

Here's the query:

SELECT
     a.account_id, a.customer_id, a.order_id, a.primary_contact_id,
     a.status,  a.customer_location_id, a.added_date,
     o.agent_id, p.order_location_id_id,
     COALESCE(a.customer_location_id, p.order_location_id) AS
order_location_id
FROM
     cust_acct a JOIN
     cust_orders o
         ON a.order_id = p.order_id;

I can't get it to run much faster that about 13 seconds, in most cases it's
more like 30 seconds.
We have a box with 8 2.5GZ cores and 28GB of ram, shared_buffers is at 8GB


I've tried separating the queries as filtering queries&  joining the
results, disabling seq scans, upping work_mem and half a dozen other
approaches.  Here's the explain plan:

  Hash Join  (cost=151.05..684860.30 rows=9783130 width=100)
    Hash Cond: (a.order_id = o.order_id)
    ->   Seq Scan on cust_acct a  (cost=0.00..537962.30 rows=9783130 width=92)
    ->   Hash  (cost=122.69..122.69 rows=2269 width=12)
          ->   Seq Scan on cust_orders o  (cost=0.00..122.69 rows=2269
width=12)

Thanks in advance for any help, tips, etc...






Explain Analyze:


 Hash Join  (cost=154.46..691776.11 rows=10059626 width=100) (actual 
time=5.191..37551.360 rows=10063432 loops=1)
   Hash Cond: (a.order_id = o.order_id)
   ->  Seq Scan on cust_acct a  (cost=0.00..540727.26 rows=10059626 
width=92) (actual time=0.022..18987.095 rows=10063432 loops=1)
   ->  Hash  (cost=124.76..124.76 rows=2376 width=12) (actual 
time=5.135..5.135 rows=2534 loops=1)
         ->  Seq Scan on cust_orders o  (cost=0.00..124.76 rows=2376 
width=12) (actual time=0.011..2.843 rows=2534 loops=1)
 Total runtime: 43639.105 ms
(6 rows)













--
---------------------------------------------
Kevin Kempter       -       Constent State
A PostgreSQL Professional Services Company
           www.consistentstate.com
---------------------------------------------


--
---------------------------------------------
Kevin Kempter       -       Constent State
A PostgreSQL Professional Services Company
          www.consistentstate.com
---------------------------------------------