From: | Ron Arts <ron(dot)arts(at)neonova(dot)nl> |
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To: | PostgreSQL List - Novice <pgsql-novice(at)postgresql(dot)org> |
Subject: | Re: Index not used in join.. (example included). |
Date: | 2009-09-18 14:27:32 |
Message-ID: | 4AB398D4.4080308@neonova.nl |
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Lists: | pgsql-novice |
Sorry. Maybe I should refrase my question.
I have two tables A and B.
Each table contains a non-unique indexed varchar column.
Table A contains around 500000 rows
table B contains around 4 million rows
for a given value of col there are typically 3 records in A and
20 records in B (give or take)
I want to do something like this:
select a.somecol from A left join B on B.col = A.col where A.date > '2001-01-01';
But this query runs for hours on an eight core server with 4G etc etc.
I configured PG to use 128Mb shared memory, but fiddling with that value
doesn't change much..
And I continuously see the planner choosing for seq scans.
I don't get it.
Ron
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