Re: "NOT IN" substantially slower in 9.0.2 than 8.3.13 - NOT EXISTS runs fast in both 8.3.13 and 9.0.2

On Thu, Jan 20, 2011 at 2:05 AM, Achilleas Mantzios
<achill@matrix.gatewaynet.com> wrote:
>                                                     ->  Hash Semi Join  (cost=2768.00..5671.67 rows=1 width=12)
(actualtime=39.249..81.025 rows=1876 loops=1) 
>                                                           Hash Cond: (msold.marinerid = msold2.marinerid)
>                                                           Join Filter: ((msold2.id <> msold.id) AND (msold2.starttime
<msold.starttime) AND ((msold.starttime - msold2.endtime) <= '1 year 6 mons'::interval)) 
>                                                           ->  Seq Scan on marinerstates msold  (cost=0.00..2889.32
rows=4590width=20) (actual time=0.003..33.964 rows=2625 loops=1) 
>                                                                 Filter: (((state)::text = 'Active'::text) AND
((starttime)::date<= '2007-01-11'::date) AND ((COALESCE(endtime, now()))::date >= '2006-07-15'::date)) 
>                                                           ->  Hash  (cost=2251.66..2251.66 rows=41307 width=24)
(actualtime=39.156..39.156 rows=41250 loops=1) 
>                                                                 Buckets: 8192  Batches: 1  Memory Usage: 2246kB
>                                                                 ->  Seq Scan on marinerstates msold2
 (cost=0.00..2251.66rows=41307 width=24) (actual time=0.002..24.552 rows=41250 loops=1) 
>                                                                       Filter: ((state)::text = 'Active'::text)

Looks like the bad selectivity estimate there is what's killing it.
Not sure I completely understand why 9.0.2 is coming up with such a
bad estimate, though.

--
Robert Haas
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