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Re: Seqscan rather than Index

From: "Steinar H(dot) Gunderson" <sgunderson(at)bigfoot(dot)com>
To: pgsql-performance(at)postgresql(dot)org
Subject: Re: Seqscan rather than Index
Date: 2004-12-17 23:55:48
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-performance
On Fri, Dec 17, 2004 at 05:02:29PM -0600, Frank Wiles wrote:
>   It depends more on your disk IO than the processor.  Counting isn't
>   processor intensive, but reading through the entire table on disk 
>   is.  I've also seen a huge difference between select count(*) and 
>   select count(1) in older versions, haven't tried it on a recent
>   version however. 

Like I said, all in cache, so no disk IO. count(*) and count(1) give me
identical results. (BTW, I don't think this is a count problem, it's a
"sequential scan" problem -- I'm just trying to find out if this is natural
or not, ie. if this is just something I have to expect in a relational
database, even with no I/O.)

/* Steinar */

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Subject: Re: Which is more efficient?
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