On 11 October 2011 19:52, CS DBA <cs_dba@xxxxxxxxxxxxxxxxxxx> wrote:
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...
Hi,
two simple questions:
- do you really need getting all 9M rows?
- show us the table structure, together with index definitions
regards
Szymon
