On Apr 2, 9:35 am, Andreas Mosmann <mosm..._at_expires-30-04-2007.news-
group.org> wrote:
> Hi ng,
>
> this is a general question about indexes and queries. I am glad about
> any hint. I can not imagine that all experienced Oracle- Gurus only work
> with try and error. There must be a strategie.
>
> At first: I actually work on Oracle 9.2.0.7 DB.
>
> If there is a query like
>
> SELECT <any_fields> FROM T1
> JOIN T2 ON T2.F1=T1.F2
> JOIN T3 ON T3.F1=T1.F3
> WHERE T2.FX=<a value> and T3.FX=<a value>
> GROUP BY T1.F4
>
> 1. What way is to go to find out what index should be created to make
> this query faster?
> 2. What (except hardware) does the performance depend on?
> 3. Is there any place I can read about it? What search string I could
> use for google search?
>
> Many thanks
> Andreas Mosmann
>
> --
> wenn email, dann AndreasMosmann <bei> web <punkt> de
1 read the explain plan, identify the driving table, and make sure the
driving table is correct (ie assuming the driving table is not a look
up table) and returns the smallest number of records. So no trial and
error involved, but 'know thy application'
2 Primarily on 'know thy application' and reading documentation, and
by avoiding putting everything on 1 single disk.
3 The concept outlined above is explained in great detail in the 'SQL
Tuning book' by Dan Tow, published by O'Reilly.
The books by Cary Millsap, Jonathan Lewis, and Tom Kyte have been
recommended here so many times, I won't recommend them further. Anyone
here can find their details by searching Google.
--
Sybrand Bakker
Senior Oracle DBA
Received on Mon Apr 02 2007 - 02:47:59 CDT
