Re: Indexing a table

From: Rustem Valeev <valeev_at_avicomp.ru>
Date: Wed, 26 Jul 2000 09:42:40 +0400
Message-Id: <10569.112968@fatcity.com>

Hi
1. The common filed should be last. Oracle use first column in query where condition only for first column
2. Uncertain question:

      Selectance of xx,x,...
      tables size
      foreing (primary) key.

   Oracle query steps: insert view source in you select, optimize query, then execute

   (although in complex query that is't fact, read "Oracle Tuning" from Oracle documentation)

aheda_at_cdotd.ernet.in wrote:

> hi
> if searching and updating a large database is required in realtime
> then indexing increases the performance a lot. I had doubt regarding the
> order of columns in which indexing needs to be done
> 1). when a compound index is t be created then what should be the order
> of the fields in the index. The common field which is same for a large no
> of rows should be the first column to be included in index or should be
> the last.
>
> 2). while operating on views does the index of the tables which are
> constituting the view are used as it is , and shoul a separate index needs
> to be created on the columns appearing tin the where clause of the view
> independently even though a composite index exists over the where clause
> of the view creation sql + the where clause of the query from the view.
>
> e.g. create view a as select b.x,c.y,c.z,c.xx
> from tableb b, tablec c,
> where b.x=c.y;
>
> a query is made as "select * from a where xx="some value";
>
> existing index on c.y + c.xx
>
> should a new index over only c.xx and only c.y and only b.x is is
> required
>
> any suggestions in this regard will be very useful
> thanks
>
>
>
> Arvind
>
>
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> Author:
> INET: aheda_at_cdotd.ernet.in
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Received on Wed Jul 26 2000 - 00:42:40 CDT