From: | Bruno Wolff III <bruno(at)wolff(dot)to> |
---|---|
To: | Stuart Woodward <woodward(at)garage(dot)co(dot)jp> |
Cc: | pgsql-novice(at)postgresql(dot)org |
Subject: | Re: how many records |
Date: | 2003-09-11 01:50:27 |
Message-ID: | 20030911015027.GA8580@wolff.to |
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Thread: | |
Lists: | pgsql-novice |
On Thu, Sep 11, 2003 at 10:20:23 +0900,
Stuart Woodward <woodward(at)garage(dot)co(dot)jp> wrote:
> > Bryan Irvine wrote:
> > Is there an easy way to count how many records there are?
>
> On Wed, 10 Sep 2003 18:26:30 +0100
> Simon Willison <cs1spw(at)bath(dot)ac(dot)uk> wrote:
>
> > Yes, using count(*):
> > select count(*) from tablename;
>
> Is there any performance difference in explicitly naming a column to
> count?
>
> i.e select count(id) from tablename;
Note that select count(id) and select count(*) can return different numbers.
Select count(*) is equivalent to select count(1) and I believe that
transformation (or something equivalent) is made by postgres.
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