On 06/01/2011 03:15 PM, Merlin Moncure wrote:
On Wed, Jun 1, 2011 at 3:14 PM, CS DBA<cs_dba@xxxxxxxxxxxxxxxxxxx> wrote:
Hi All;
We have a table with approx 200 columns. about a dozen columns are text data
types and the rest are a mix of integers , bigint's and double precision
types.
The table has about 25million rows.
The app wants to run a query like this:
select count(pri_num) from max_xtrv_st_t
where pri_num in (select max(pri_num) from max_xtrv_st_t where 1=1
group by tds_cx_ind, cxs_ind_2 )
I've tried to split the query up but made little progress, pri_num and
tds_cx_ind are bigint's and cxs_ind_2 is an integer
The table has an index on all 3 columns (3 separate indexes)
Anyone have any thoughts on tuning this query?
need postgres version# and the current explain analyze (or explain, if
you can't wait for it)
merlin
Postgresql version 8.4.2
Explain:
QUERY PLAN
------------------------------------------------------------------------------------------------
Aggregate (cost=6551481.85..6551481.86 rows=1 width=8)
-> Nested Loop (cost=6550474.85..6551481.35 rows=200 width=8)
-> HashAggregate (cost=6550474.85..6550476.85 rows=200 width=8)
-> GroupAggregate (cost=5918263.18..6334840.58
rows=17250742 width=20)
-> Sort (cost=5918263.18..5968498.96
rows=20094312 width=20)
Sort Key: tds_cx_ind, cxs_ind_2
-> Seq Scan on max_xtrv_st_t
(cost=0.00..3068701.12 rows=20094312 width=20)
-> Index Scan using max_xtrv_st_t_pkey on max_xtrv_st_t
(cost=0.00..5.01 rows=1 width=8)
Index Cond: (max_xtrv_st_t.pri_num =
(max(max_xtrv_st_t.pri_num)))
(9 rows)
--
---------------------------------------------
Kevin Kempter - Constent State
A PostgreSQL Professional Services Company
www.consistentstate.com
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