Anyone have any ideas why this query would be so slow?

stats=# explain analyze SELECT work_units, min(raw_rank) AS rank  FROM 
Trank_work_overall GROUP BY work_units;
                                                          QUERY PLAN                   
 HashAggregate  (cost=1050.12..1085.98 rows=14347 width=16) (actual 
time=163149.981..163227.758 rows=17849 loops=1)
   ->  Seq Scan on trank_work_overall  (cost=0.00..804.41 rows=49141 width=16) (actual 
time=0.071..328.682 rows=49091 loops=1)
 Total runtime: 163296.212 ms

(3 rows)

stats=# \d Trank_work_overall
Table "pg_temp_1.trank_work_overall"
   Column   |  Type  | Modifiers 
 raw_rank   | bigint | 
 work_units | bigint | 


FreeBSD 5.2.1-RELEASE FreeBSD 5.2.1-RELEASE #1:
Wed Apr  7 18:42:52 CDT 2004
[EMAIL PROTECTED]:/usr/obj/usr/src/sys/FRITZ  amd64

The machine is a dual opteron with 4G of memory. The query in question
was not hitting the disk at all. PostgreSQL 7.4.2 compiled with -O3.

Also, if I set enable_hashagg = false, it runs in less than a second.
Jim C. Nasby, Database Consultant                  [EMAIL PROTECTED]
Member: Triangle Fraternity, Sports Car Club of America
Give your computer some brain candy! Team #1828

Windows: "Where do you want to go today?"
Linux: "Where do you want to go tomorrow?"
FreeBSD: "Are you guys coming, or what?"

---------------------------(end of broadcast)---------------------------
TIP 5: Have you checked our extensive FAQ?


Reply via email to