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default optimizer_mode [message #645867] Tue, 15 December 2015 10:00 Go to next message
yk107
Messages: 15
Registered: October 2015
Junior Member
is there default optimizer_mode in ORACLE database ? and there is any way to change it ?

Thanks
Re: default optimizer_mode [message #645869 is a reply to message #645867] Tue, 15 December 2015 10:04 Go to previous messageGo to next message
BlackSwan
Messages: 25856
Registered: January 2009
Location: SoCal
Senior Member
https://docs.oracle.com/apps/search/search.jsp?category=database&product=e50529-01&q=optimizer_mode

Are SEARCH & GOOGLE broken for you?
Re: default optimizer_mode [message #645875 is a reply to message #645869] Tue, 15 December 2015 10:50 Go to previous messageGo to next message
yk107
Messages: 15
Registered: October 2015
Junior Member
Thank you BlackSwan
Re: default optimizer_mode [message #646673 is a reply to message #645875] Wed, 06 January 2016 13:25 Go to previous messageGo to next message
garan
Messages: 27
Registered: January 2016
Junior Member
Hi

Just a note

The optimizer_mode in earlier version say 8i had RULE | CHOOSE | FIRST_ROWS | ALL_ROWS} this got changed in 10G as RULE based optimizer got deprecated. Here CHOOSE implies it will go for rule if the statistics are not available otherwise it will go for cost based if statistics were available for a given table.

Hence in 10g it was first_rows_[1 | 10 | 100 | 1000] | first_rows | all_rows }

garan
Re: default optimizer_mode [message #646677 is a reply to message #646673] Wed, 06 January 2016 13:44 Go to previous messageGo to next message
Michel Cadot
Messages: 65385
Registered: March 2007
Location: Nanterre, France, http://...
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Account Moderator

Who care about Oracle 8i? or 10g?
Why don't you talk about Oracle 7? or 6? or 5?

Re: default optimizer_mode [message #646691 is a reply to message #646677] Wed, 06 January 2016 23:07 Go to previous messageGo to next message
garan
Messages: 27
Registered: January 2016
Junior Member
Thank you

I understand not many people are working in 8i they would have moved to Oracle 10g/11g/12c.

I worked in Oracle 8i, Oracle 10g, Oracle 11g I always try to make comparison what functionalities are new from 8i to 10g and 10g to 11g

This is one way of learning things
Re: default optimizer_mode [message #646704 is a reply to message #646691] Thu, 07 January 2016 01:22 Go to previous messageGo to next message
Michel Cadot
Messages: 65385
Registered: March 2007
Location: Nanterre, France, http://...
Senior Member
Account Moderator

But most of those who ask here didn't work with version lower than 10g and adding information about or comparison with these versions just add confusion.
Should I compare the optimizer version 4 with version 10g or 12c one just because I worked with it?

Re: default optimizer_mode [message #646878 is a reply to message #646704] Tue, 12 January 2016 20:15 Go to previous messageGo to next message
yaokevin1987@gmail.com
Messages: 8
Registered: August 2013
Location: changchun
Junior Member
You can use the command at the sqlplus as " show parameter optimize" to check the parameter.
Re: default optimizer_mode [message #646879 is a reply to message #646878] Tue, 12 January 2016 23:30 Go to previous message
yk107
Messages: 15
Registered: October 2015
Junior Member
great , thank you for advice
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