Re: Sort on column def.

From: Tanel Poder <>
Date: Wed, 9 Sep 2009 23:19:51 +0800
Message-ID: <>

Not sure whether it answers your question directly, but Jonathan Lewis has written about sorted hash cluster internals in past:

Tanel Poder

On Wed, Sep 9, 2009 at 10:56 PM, Brady, Mark

> *10gR2 Docs:*
> The SORT keyword is valid only if you are creating this table as part of a
> hash cluster and only for columns that are also cluster columns.
> This clause instructs the database to sort the rows of the cluster on this
> column before applying the hash function. Doing so may improve response time
> during subsequent operations on the clustered data.
> I don’t get it. My rudimentary understanding is: Oracle uses a hash
> function on the clustered column that would produce a “Block offset” and
> place that row there… so the location of the row is predetermined, what does
> it buy to sort the inserts? Is it purely an efficient space allocation
> thing? If done in order, the less likely to chain rows? Something like that?
Received on Wed Sep 09 2009 - 10:19:51 CDT

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