Re: Optimizer and ANSI Joins
Date: Tue, 29 Jan 2019 20:49:48 +0300
Message-ID: <CAOVevU7N5ysPnVimYg+rOo3iJyZg=-ER6ac8SKwT9zqOG8EmzA_at_mail.gmail.com>
Hi Jared,
Of course, cbo understand ansi joins, because it transforms them into own
syntax :)
You can check 10053 trace or dbms_sql2.expand_sql_text
(DBMS_UTILITY.expand_sql_text since 12c)
вт, 29 янв. 2019 г., 20:10 Jared Still jkstill_at_gmail.com:
> Hello All:
(with some nuances like full outer join(it has now native full outer join,
but not in syntax yet) or outer join to more than one table before 12c)
>
> Something I have heard a few times is that the Oracle Optimizer does not
> understand ANSI joins, and that ANSI joins are first converted to some
> legacy format before the optimizer processes them.
>
> Does anyone here know if there is any truth in this?
>
> Some things that come to mind:
>
> - perhaps it was true at one time (9i)
> - only partially true
> - a blatant lie started by a SQL Server Fan.
>
> OK, that last one was uncalled for, but a little humor is necessary
> sometimes :)
>
> I have googled around for this a bit, but find nothing that really
> discusses the topic.
>
> Thanks,
>
> Jared Still
> Certifiable Oracle DBA and Part Time Perl Evangelist
> Principal Consultant at Pythian
> Pythian Blog http://www.pythian.com/blog/author/still/
> Github: https://github.com/jkstill
>
>
>
-- http://www.freelists.org/webpage/oracle-lReceived on Tue Jan 29 2019 - 18:49:48 CET