From: | Bruce Momjian <maillist(at)candle(dot)pha(dot)pa(dot)us> |
---|---|
To: | t-ishii(at)sra(dot)co(dot)jp |
Cc: | pgsql-hackers(at)hub(dot)org |
Subject: | Re: [HACKERS] using a btree index in order by clause? |
Date: | 1998-06-17 10:44:34 |
Message-ID: | 199806171044.GAA18849@candle.pha.pa.us |
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Thread: | |
Lists: | pgsql-hackers |
>
> Hi,
>
> I'm wondering if we can use btree index to sort the results in a
> certain condition. The idea is, if the order-items in the order by
> clause have a btree index, then why we need to sort them again?
>
> I'm starting to look at the executor code. However this kind of
> "optimization" might be better to be done in the optimizer, I don't
> know.
FYI, often, using an index to sort a tables is SLOWER than loading all the
rows into psort and sorting them, because the index causes random seeks
all over the table.
--
Bruce Momjian | 830 Blythe Avenue
maillist(at)candle(dot)pha(dot)pa(dot)us | Drexel Hill, Pennsylvania 19026
+ If your life is a hard drive, | (610) 353-9879(w)
+ Christ can be your backup. | (610) 853-3000(h)
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