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default optimizer_mode [message #645867]

Tue, 15 December 2015 10:00

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

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Re: default optimizer_mode [message #645869 is a reply to message #645867]

Tue, 15 December 2015 10:04

BlackSwan
Messages: 26766
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?

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Re: default optimizer_mode [message #645875 is a reply to message #645869]

Tue, 15 December 2015 10:50

yk107
Messages: 15
Registered: October 2015

Junior Member

Thank you BlackSwan

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Re: default optimizer_mode [message #646673 is a reply to message #645875]

Wed, 06 January 2016 13:25

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

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Re: default optimizer_mode [message #646677 is a reply to message #646673]

Wed, 06 January 2016 13:44

Michel Cadot
Messages: 68341
Registered: March 2007
Location: Nanterre, France, http://...

Senior Member
Account Moderator

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

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Re: default optimizer_mode [message #646691 is a reply to message #646677]

Wed, 06 January 2016 23:07

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

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Re: default optimizer_mode [message #646704 is a reply to message #646691]

Thu, 07 January 2016 01:22

Michel Cadot
Messages: 68341
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?

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