Re: Row versions and indexes

From: Alan Hodgson <ahodgson(at)simkin(dot)ca>
To: pgsql-general(at)postgresql(dot)org
Subject: Re: Row versions and indexes
Date: 2006-09-28 22:06:49
Message-ID: 200609281506.49687@hal.medialogik.com
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On Thursday 28 September 2006 14:58, "Jack Orenstein"
<jack(dot)orenstein(at)gmail(dot)com> wrote:
> How does versioning work for the index?
>
> - The update above does not update the index key. Does the index get
> updated at all?
>

Yes, it does.

> - If not, then how can an index lookup return the correct version of
> selected rows?
>
> This aspect of versioning has never been clear to me. Now there's a cost
> issue involved, as I need to update every row in a large table, never
> updating the index key. Will this run faster if I drop the index?
> (Yes, I can run the experiment, but I'd like to understand the
> fundamentals better.)

Yes, it certainly will.

--
"A government that robs Peter to pay Paul can always depend upon the support
of Paul." - George Bernard Shaw

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