Mark,
thanks, interesting article. But I'm still getting the feeling that the
index skip scan is helpful only when you don't want to create a
secondary index on columns that are not the left-most column. since I
believe that we will be doing a LOT of queries by order date as well,
I'm not sure that the benefits of defaulting to index skip scan
outweigh the benefits of just having the second index.
Rachel
- Mark Leith <mark_at_cool-tools.co.uk> wrote:
> Rachel,
>
>
http://technet.oracle.com/oramag/webcolumns/2003/techarticles/schumacher_ski
> pscan.html
> http://www.oracle-base.com/Articles/9i/IndexSkipScanning.asp
>
> I don't have any personal experience with them myself :( The first
> link
> gives a pretty good overview though..
>
> Mark
>
> -----Original Message-----
> Carmichael
> Sent: 28 May 2003 12:00
> To: Multiple recipients of list ORACLE-L
>
>
> Okay, I have a developer here who has been reading the docs (this can
> be dangerous!)
>
> we are adding functionality to one of our applications, this will
> involve using multiple fulfillment houses, so we'll be adding the
> fulfillment vendor id to the order table. Easy, this is not a
> problem.
> We want to be able to search by order date and by fulfillment vendor
> id/order date
>
> Traditional design would be to add two indexes: one on order date,
> and
> a concatenated one on fulfillment vendor id/order date.
>
> The developer is telling me to create a "skip scan index" instead of
> two different ones. MY reading in the FM tells me that skip scan
> index
> is not a type of index, but rather a way Oracle uses to use an index
> even if the leftmost column is not in the query.
>
> Is there any benefit in my building only the one index? Our order
> volume is not so high (and never will be) that there is a visible
> performance impact if I have the two indices.
>
> This is 9i, 9.2.0.1, will be upgrading to 9.2.0.2 in the near future.
> Solaris
>
> Any suggestions/comments/war stories would be appreciated. I know
> I've
> seen Jonathan post on skip scan indexes before but I can't find the
> specific reference at the moment.
>
> Rachel
>
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Received on Wed May 28 2003 - 08:25:07 CDT
