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when was COST optimizer introduced ? [message #190321] Wed, 30 August 2006 04:00 Go to next message
tridentadm
Messages: 142
Registered: March 2006
Senior Member
OPTIMIZER_FEATURES_ENABLE=9.2.0;

This statement causes the Release 2 (9.2) optimizer features to be used in generating query plans. For example, you can use ALL_ROWS or FIRST_ROWS optimizer mode for recursive user SQL generated by PL/SQL procedures. Prior to Oracle8i Release 8.1.6, only RULE or CHOOSE optimizer mode was used for such recursive SQL, and when the user explicitly set the OPTIMIZER_MODE parameter to FIRST_ROWS or ALL_ROWS, a CHOOSE mode was used instead.

can someone tell me when COST based optimizer was introduced ?
Re: when was COST optimizer introduced ? [message #190344 is a reply to message #190321] Wed, 30 August 2006 05:37 Go to previous messageGo to next message
wagnerch
Messages: 58
Registered: July 2006
Member
Oracle 7.0

http://orafaq.com/faq/features_introduced_in_the_various_server_releases

but, I don't believe it was default until Oracle 8i. I believe RBO was default prior to 8i.
Re: when was COST optimizer introduced ? [message #190346 is a reply to message #190321] Wed, 30 August 2006 05:43 Go to previous messageGo to next message
seemit
Messages: 7
Registered: July 2006
Junior Member
ALL_ROWS or FIRST_ROWS, no matter which HINT i choose, it is not going to give me performance boost as required. ALL_ROWS will lower the number of disk block accesses but may reduce the time to compute. wherein FIRST_ROWS_ will make more n more disk block accesses and will keep providing me rows, but it may even take more time to give me ALL the rows. <--- WHAT I KNW.

and about CBO, you can easily google. but I think it was introduced with Oracle 8
Re: when was COST optimizer introduced ? [message #190531 is a reply to message #190346] Thu, 31 August 2006 03:30 Go to previous message
JRowbottom
Messages: 5933
Registered: June 2006
Location: Sunny North Yorkshire, ho...
Senior Member
CBO came in with 7.0 but had some serious issues up until roughly release 7.3.4 (I know it was pretty flaky at 7.3.2).

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