Topic: Performance & Tuning >> Query Rewrite
|
Disclaimer: The purpose of all dbapool forums including OCP and Other Oracle Certification forums is to help each other with specific issues but not to share dump and copyrighted exam content, materials or intellectual property.
You may review the entire Oracle Certification Program Candidate Agreement online Here.
|
|
|
|
| rsreddy28 |
Posted: Mar 17, 2007 03:47:44 AM |
Total Post: 36
Joined: Mar, 2007
|
Hello,
Can somebody tell me what is Query Rewrite. I got this question in an interview. I just told that it is used to improve the performance of queries by avoiding repeated statements.
Plz help me giving out what exactly happens inside with Query Rewrite and also the detailed script and how is it and where is it used.
Regards,
Rajasekhar Reddy |
|
|
naren |
| Posted: Mar 17, 2007 05:02:25 PM | |
|
Total Post: 6
Joined: Mar, 2007
|
Hello...
When a query executes, the optimizer decides whether it is faster to access the materialized view or the underlying tables where the data resides. If the optimizer decides that querying the materialized view is the better solution, the optimizer rewrites the SQL query in a process known as query rewrite. This process occurs without requiring a change to any SQL or application code, so any application or ad hoc query tool that uses SQL to access the database can benefit by using the materialized view. Query rewrite works best where the amount of data accessed to compute the result is significantly greater than the size of the result, such as aggregation; however, it can also be used to speed up expensive joins or projections.
regards
-naren
|
|
|
|
|
| Time Zone: EDT |
Send this thread to your friend |
|
|
|
|
Forum Rules & Description
Who Can Read The Forum? Any registered user or guest
Who Can Post New Topics? Any registered user
Who Can Post Replies? Any registered user
|
| |
Get FREE Magazines
|
Top 10 Forum User
|
| Murtuja Khokhar | 857 |
| Mohammed Taj | 746 |
| positive fanatic | 483 |
| Jayanta Sur | 479 |
| Vigyan Kaushik | 386 |
| Gopu Gopi | 333 |
| Gitesh Trivedi | 322 |
| Vinoth Kumar | 264 |
| neeraj sharma | 258 |
| Ramesh Jois | 246 |
|
|