From: Dan Harris <fbsd@drivefaster.net>
To: pgsql-performance@postgresql.org
Subject: Re: Seq Scan
Date: Fri, 01 Jun 2007 10:59:01 -0600
Message-ID: <46605055.3070305@drivefaster.net> (raw)
In-Reply-To: <ab07320e0706010948m7c4eb1b8s9cdaf79b1c400125@mail.gmail.com>
References: <ab07320e0706010948m7c4eb1b8s9cdaf79b1c400125@mail.gmail.com>
Tyler Durden wrote:
> Hi,
> I'm having some problems in performance in a simple select count(id)
> from.... I have 700 000 records in one table, and when I do:
>
> # explain select (id) from table_name;
> -[ RECORD 1
> ]----------------------------------------------------------------
> QUERY PLAN | Seq Scan on table_name (cost=0.00..8601.30 rows=266730
> width=4)
>
> I had created an index for id(btree), but still shows "Seq Scan".
> What I'm doing wrong?
>
> Thanks,
> Tyler
>
> ---------------------------(end of broadcast)---------------------------
> TIP 4: Have you searched our list archives?
>
> http://archives.postgresql.org
select count(*) will *always* do a sequential scan, due to the MVCC
architecture. See archives for much discussion about this.
-Dan
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To: pgsql-performance@postgresql.org
Cc: fbsd@drivefaster.net
Subject: Re: Seq Scan
In-Reply-To: <46605055.3070305@drivefaster.net>
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