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Home -> Community -> Usenet -> c.d.o.server -> Re: Efficient SQL
Oracle will evaluate WHERE and FROM clause of SQL statement with bottom-up
approach under rule-based optimizer environment. If you really want to tune
up your SQL, you should pay more attention on not only the WHERE and FROM
clause but also indexes, embedded funciton in WHERE clause, join condition,
etc... you should get information about this kind of tunning technique from
many Oracle books. But I recommended a book called "Performance Tuning"
from O'Reily.
Altitude wrote:
> Hi,
>
> We've been looking at improving the efficiency and peformance of some
> Oracle SQL (Both in Pro*C and in triggers). I've found out that for
> SELECT statements, the FROM clause should always have the smallest table
> last (since this is the driving table). Why is this? How does Oracle
> actually parse a SELECT stament and why is this method more efficient?
> My second question is more general ... are there any books which discuss
> the performance and effciency issues with respect to Oracle SQL?
> Nothing to complicated, as I'm only a beginner, but just something which
> will explain to me how to write efficient joins for example.
>
> Any help will be greatly appreciated.
> Thanks in advance.
--
Best Regards,
Reid Lai
Oracle 7.3 Certified DBA (OCP)
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