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List:       pgsql-bugs
Subject:    [BUGS] BUG #8196: problem with left join and is null check
From:       aray1985 () yahoo ! com
Date:       2013-05-31 15:03:00
Message-ID: E1UiQr6-0008IE-IG () wrigleys ! postgresql ! org
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The following bug has been logged on the website:

Bug reference:      8196
Logged by:          Ara
Email address:      aray1985@yahoo.com
PostgreSQL version: 9.1.9
Operating system:   ubuntu
Description:        

I have to tables which I'm joining with left join query.

SELECT count(*) FROM
table A LEFT JOIN table B ON ...

result has 200 000 rows, for 190 000 of them there is no value for columns
of table B (result of join)

ISSUE: When I'm trying to filter result with WHERE B.some_column IS NULL
query works more then 5 min (never waited for result). 

MORE INFO:
When I'm filtering results with WHERE B.some_column IS NULL OR B.some_column
= 'some value that some_column would never had' the query takes 2 second and
gives normal result (190 000).



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