I think that all new CBO parameters introduced in Oracle release x
(12.1.0.1 for example) will be unset if you decide to set the optimizer
mode at release x-1 (11.2.0.4 for example) during your upgrade process from
11gR2 to 12cR1. Actually I got the same question when I wanted to set the
_optimizer_ansi_join_lateral_enhance
<https://hourim.wordpress.com/2017/06/02/_optimizer_ansi_join_lateral_enhance/>
parameter to FALSE in a 12cR1 and was trying to find if other applications
have already done this before me. Indeed I find that this parameter has
been unset in several 12cR1 databases without any specific alter system
command. All those applications have a common caracteristic: they have set
the optimizer mode to 11.2.0.4 during their upgrade process to 12cR1.
Best regards
Mohamed Houri
2018-03-01 16:38 GMT+01:00 Franck Pachot <franck@xxxxxxxxxx>:
Hi,
This parameter is always false except if you put the
optimizer_features_enable to higher than the current version (12.2.0.1.1
for example for your 12.2.0.1).
See: https://blog.dbi-services.com/oracle-121021-set-to-join-conversion/
I don't know why they do that. it is still the case in 18c where it is
enabled only if you set OFE=18.1.0.1 where the default is 18.1.0
Regards,
Franck.
On Thu, Mar 1, 2018 at 3:31 PM Noveljic Nenad <nenad.noveljic@xxxxxxxxxxxx>
wrote:
Could you please check the value of _convert_set_to_join on your
12.2.0.1.180116 database?
I’m trying to figure out what kind of condition might have flipped it to
FALSE (the value wasn’t set in the spfile):
select a.ksppinm name,b.ksppstvl value,b.ksppstdf deflt,
decode
(a.ksppity, 1,
'boolean', 2,
'string', 3,
'number', 4,
'file', a.ksppity) type,
a.ksppdesc description
from
sys.x$ksppi a,
sys.x$ksppcv b
where
a.indx = b.indx
and
a.ksppinm like '%convert_set_to_join%'
order by
name ;
NAME
------------------------------------------------------------
--------------------
VALUE
------------------------------------------------------------
--------------------
DEFLT TYPE
--------- ----------------------------------------
DESCRIPTION
------------------------------------------------------------
--------------------
_convert_set_to_join
FALSE
TRUE boolean
enables conversion of set operator to join
I’m on Solaris x86-64 (not sure if it matters).
Thanks,
Nenad
http://nenadnoveljic.com/blog/
____________________________________________________
Please consider the environment before printing this e-mail.
Bitte denken Sie an die Umwelt, bevor Sie dieses E-Mail drucken.
Important Notice
This message is intended only for the individual named. It may contain
confidential or privileged information. If you are not the named addressee
you should in particular not disseminate, distribute, modify or copy this
e-mail. Please notify the sender immediately by e-mail, if you have
received this message by mistake and delete it from your system.
E-mail transmission may not be secure or error-free as information could
be intercepted, corrupted, lost, destroyed, arrive late or incomplete. Also
processing of incoming e-mails cannot be guaranteed. All liability of the
Vontobel Group and its affiliates for any damages resulting from e-mail use
is excluded. You are advised that urgent and time sensitive messages should
not be sent by e-mail and if verification is required please request a
printed version.
