RE: should one use ANSI join syntax when writing an Oracle applic ation?

From: Ken Naim <kennaim_at_gmail.com>
Date: Thu, 19 Oct 2006 16:12:54 -0500
Message-ID: <009801c6f3c3$5a325c60$85e7cf48@KenHome>

Well, I know for a fact that this is the case in 10g as it happened to me just the other day. I had a situation where a.x=b.x and a.x in ('a','b','c',.... etc.) and the optimizer choose to use an index on b.x

Ken

-----Original Message-----
From: oracle-l-bounce_at_freelists.org [mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Allen, Brandon
Sent: Thursday, October 19, 2006 11:50 AM To: paul.baumgartel_at_credit-suisse.com; breitliw_at_centrexcc.com; Jacques.Kilchoer_at_quest.com
Cc: oracle-l
Subject: RE: should one use ANSI join syntax when writing an Oracle applic ation?

I thought Oracle was smart enough to perform transitive closure on its own even if you don't explicitly write it in your SQL, e.g. Metalink #68979.1:

"Transitivity and Transitive Closure

---

Purpose

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This article explains how the Cost Based Optimizer (CBO) generates transitive
predicates to open potential new access methods."

> -----Original Message-----
> From: oracle-l-bounce_at_freelists.org
> [mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Baumgartel, Paul
> Wolfgang,
>
> Just to confirm, your point is that adding
> the (logically unnecessary) "and A.x = C.x" provides more
> information that the optimizer can use to choose a more
> efficient access path?
>
>
>
> -----Original Message-----
> From: oracle-l-bounce_at_freelists.org
> [mailto:oracle-l-bounce_at_freelists.org]On Behalf Of Wolfgang Breitling
>
> I need some help here. How do I code a full transitive
> closure join with the new syntax? In the traditional syntax I can say:
>

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Received on Thu Oct 19 2006 - 16:12:54 CDT