From: | Tomaz Borstnar <tomaz(dot)borstnar(at)over(dot)net> |
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To: | pgsql-performance(at)postgresql(dot)org |
Subject: | Re: any way to use indexscan to get last X values |
Date: | 2003-06-15 15:17:04 |
Message-ID: | 5.2.1.1.0.20030615171224.01c32eb0@127.0.0.1 |
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Lists: | pgsql-performance |
At 16:31 15.6.2003, Shridhar Daithankar wrote:
>Question. The field approved seems to have boolean values. If probability of
>having either of value is 50%, I doubt planner will use index anyway.
True. It has Y or N only so index on approved is useless. But using index
on ORDER BY part would help a lot since it knows to fetch last X ordered
values.
>Correct me if I am wrong.
Unfortunately you are very right.
I am not sure how to stuff modifystamp and thread into WHERE clause to make
it use indexes on thread and/or modifystamp. So far I believe this would be
the only way to use them, right?
Tomaz
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