Chuck D. wrote:
On Monday 21 May 2007 03:14, Josh Berkus wrote:
Chuck,
Can we see the plan?
--Josh
Sorry Josh, I guess I could have just used EXPLAIN instead of EXPLAIN
ANALYZE.
# explain
SELECT country_id, country_name
FROM geo.country
WHERE country_id IN
(select country_id FROM geo.city)
;
QUERY PLAN
--------------------------------------------------------------------
Nested Loop IN Join (cost=0.00..1252.60 rows=155 width=15)
Join Filter: (country.country_id = city.country_id)
-> Seq Scan on country (cost=0.00..6.44 rows=244 width=15)
-> Seq Scan on city (cost=0.00..43409.12 rows=2122712 width=2)
The only thing I can think of is that the CLUSTERing on city.country_id
makes the system think it'll be cheaper to seq-scan the whole table.
I take it you have got 2 million rows in "city"?
--
Richard Huxton
Archonet Ltd
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