Re: query rewrite
- From: Toon Koppelaars <toon.koppelaars@xxxxxxxxxxx>
- To: Marcin Przepiorowski <pioro1@xxxxxxxxx>
- Date: Wed, 30 Dec 2009 18:53:20 +0100
Ahh yes, you are absolutely right. I missed that.
The CBO could only rewrite it, if it knew that code_vl is a (declared) key
in table X. Then and only then would the two queries be semantically
equivalent.
On Wed, Dec 30, 2009 at 9:49 AM, Marcin Przepiorowski <pioro1@xxxxxxxxx>wrote:
>
> On Wed, Dec 30, 2009 at 6:19 AM, kyle Hailey <kylelf@xxxxxxxxx> wrote:
>
>>
>> one difference -
>> the first query will break if the correlated sub query returns more than
>> one value where as the second query will return the mulitple rows.
>>
>>
> Hi Kyle,
>
> I have spend last 2 weeks working with query as in 1 example
> and subquery never has been pushed into FROM section.
> My general execution plan in 10.1.0.4 looks like this
>
> SELECT STATEMENT
> TABLE ACCESS - X - or join of more then one table
> SORT
> TABLE ACCESS - F - or join of more then one table
>
> or
>
> SELECT STATEMENT
> TABLE ACCESS - X - or join of more then one table
> FILTER
> TABLE ACCESS - F - or join of more then one table
>
>
> regards,
> Marcin Przepiorowski
> http://oracleprof.blogspot.com/
>
>
--
Toon Koppelaars
RuleGen BV
Toon.Koppelaars@xxxxxxxxxxx
www.RuleGen.com
TheHelsinkiDeclaration.blogspot.com
(co)Author: "Applied Mathematics for Database Professionals"
www.RuleGen.com/pls/apex/f?p=14265:13
Other related posts:
