23.03.11 09:30, Adarsh Sharma написав(ла):
Thanks Chetan, here is the output of your updated query :
explain select distinct(p.crawled_page_id) from page_content p
where
NOT EXISTS (select 1 from clause2 c where c.source_id =
p.crawled_page_id);
QUERY
PLAN
---------------------------------------------------------------------------------------
HashAggregate (cost=1516749.47..1520576.06 rows=382659 width=8)
-> Hash Anti Join (cost=1294152.41..1515791.80 rows=383071
width=8)
Hash Cond: (p.crawled_page_id = c.source_id)
-> Seq Scan on page_content p (cost=0.00..87132.17
rows=428817 width=8)
-> Hash (cost=771182.96..771182.96 rows=31876196
width=4)
-> Seq Scan on clause2 c (cost=0.00..771182.96
rows=31876196 width=4)
(6 rows)
And my explain analyze output is :
QUERY
PLAN
--------------------------------------------------------------------------------------------------------------------------------------------
HashAggregate (cost=1516749.47..1520576.06 rows=382659 width=8)
(actual time=56666.181..56669.270 rows=72 loops=1)
-> Hash Anti Join (cost=1294152.41..1515791.80 rows=383071
width=8) (actual time=45740.789..56665.816 rows=74 loops=1)
Hash Cond: (p.crawled_page_id = c.source_id)
-> Seq Scan on page_content p (cost=0.00..87132.17
rows=428817 width=8) (actual time=0.012..715.915 rows=428467
loops=1)
-> Hash (cost=771182.96..771182.96 rows=31876196
width=4)
(actual time=45310.524..45310.524 rows=31853083 loops=1)
-> Seq Scan on clause2 c (cost=0.00..771182.96
rows=31876196 width=4) (actual time=0.055..23408.884 rows=31853083
loops=1)
Total runtime: 56687.660 ms
(7 rows)
But Is there is any option to tune it further and one more thing
output
rows varies from 6 to 7.
You need an index on source_id to prevent seq scan, like the next:
CREATE INDEX idx_clause2_source_id
ON clause2
(source_id);
Best regards, Vitalii Tymchyshyn
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