From: | "Joshua D(dot) Drake" <jd(at)commandprompt(dot)com> |
---|---|
To: | Ow Mun Heng <Ow(dot)Mun(dot)Heng(at)wdc(dot)com> |
Cc: | pgsql-general(at)postgresql(dot)org |
Subject: | Re: Indexes & Primary Keys (based on the same columns) |
Date: | 2007-10-22 03:49:58 |
Message-ID: | 471C1DE6.4090503@commandprompt.com |
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Thread: | |
Lists: | pgsql-general |
Ow Mun Heng wrote:
> I'm wondering if what I'm doing is redundant.
>
> I have a primary key on columns (A,B,C,D)
> and I've also defined an index based on the same columns (A,B,C,D)
>
> and sometimes in the query explain, I see the pkey being used for the
> scan instead of the index.
>
> So.. That made me think perhaps the additional index on the _same_
> parameter is redundant.
A primary key creates an index so having a second index with the same
definition is redundant.
>
> Appreciate comments.
>
>
>
> ---------------------------(end of broadcast)---------------------------
> TIP 9: In versions below 8.0, the planner will ignore your desire to
> choose an index scan if your joining column's datatypes do not
> match
>
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