Oracle DBA Information at one place

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on August 11, 2014

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Oracle DBA ALL Interview questions and answers..

Oracle DBA ALL Interview questions and answers.. Flash back interview questions: ************************************** Questions you always wanted to ask about Flashback Database… Nov 6, 2009 / By André Araujo Tags: Oracle Last Friday in the Sydney Oracle Meetup I talked about Oracle Flashback technology and how it helps to reduce downtime. The session generated great interest among the attendees, which led to interesting discussions and many questions about the subject. Some of the questions couldn’t be answered during the meeting so I’ve followed up on them and I’m posting the answers here since they may be of interest for many others. Q: Is there a separate background process for writing flashback logs? A: Yes. RVWR (Recovery Writer, a.k.a Flashback Writer) was introduced in Oracle 10g to write flashback data from the Flashback Buffer in the SGA to the flashback database logs on disk. Q: Do I need to shutdown and mount the database to turn flashback on? A: A

How to read AWR reports

How to read AWR reports : The output of the AWR report contains a wealth of information that you can use to tune your database. The output of the AWR report can be divided into the following sections: Report Header This section is self explanatory which provides database name, id, instance if RAC , platform information and snap interval. (database workload time duration in review). This report is for instance number 2 of my RAC environment. So if you need to the analysis on RAC environment, you need to do it separately of all the instances in the RAC to see if all the instances are balanced the way they should be. DB Name DB Id Instance Inst num Startup Time Release RAC TestRAC 3626203793 TestRac2 2 17-Aug-11 19:08 11.1.0.6.0 YES Host Name Platform CPUs Cores Sockets Memory (GB) T estRAC Linux 64-bit for AMD 8 8 2 31. 44 Snap Id Snap Time Sessions Cursors/Session Begin Snap: 28566 27-Sep-11 01:00:21 130 4.8 End Snap: 28567 27-Sep-11 02:00:43 135 4.5 Elapsed:

Diagnosing Why a Query is Not Using an Index

Diagnosing Why a Query is Not Using an Index PURPOSE This article is intended to assist with the question : Why is my index not used? TROUBLESHOOTING STEPS Understanding ' Why my index is not being used? ' is a big topic as there are many varied reasons for indexes not being used. The following is a helpful checklist. Click on the links below to jump to the relevant section of the article: Quick Initial Checks The table is indexed, isn't it? Check that the table which you believe should be accessed via an index actually has indexes defined on it. The indexes could have been dropped or could have failed to create - For example, it is possible, after importing tables, or performing loads, that indexes were not created due to errors (either software or human). The following query shows an example of checking for indexes: SELECT index_name FROM user_indexes WHERE table_name = &Table_Name; Why SHOULD the index be used? Oracle does not have to use

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