Archive for the ‘oracle dba tips’ Category

What are the Responsibilities of Oracle DBA?

January 21, 2019 Comments off

Oracle DBA resposibilitiesThere are lots of responsibilities of Oracle DBA. Oracle DBA role plays a very significant part of the company. The database administrator is the key person of a company because he or she manages that database server which contains the company’s most important and sensible data.

Oracle database administrator manage database administration tasks like

  • general administration,
  • user administration,
  • security management,
  • network management,
  • space management,
  • backup and recovery,
  • performance and tuning of database servers,
  • migration and upgrade,
  • moving data across the databases and servers,
  • manages mysterious serious error like 600, 700, 7445 etc,
  • recover from human data loss errors,
  •  recover from logical corruption,
  • recover from physical corruption,
  • deployment of the standby database server,
  • maintain database licenses,
  • maintain database inventory,
  • maintain database documentation.

Version by version, Oracle introduces lots of new automation features and as per new feature database administrator’s job and tasks have been changing.

As new Oracle cloud DBaaS has been introduced. The new Oracle 18c database introduced too with a lot of autonomous features.  As per these new database versions and features tasks and responsibilities are changed.

Still, some people have the question in mind that Oracle is going to discontinued Oracle DBA role. Some of the experience and intermediate administrators fear due to this reason.

But it is an only rumor. Tasks and responsibilities are being changed as per the new version released by Oracle. Don’t bother about same. DBA always plays a key role in any company.


Tablespace Encryption Oracle 12c More Powerful

January 21, 2019 Comments off

remote dba expertsOracle Business Intelligence bring the complete specter of Business Intelligence functions, from reports of the whole company, scorecards, board panels, ad hoc interrogations, OLAP analysis, and search, to action generating collaboration, everything on an integrated technological infrastructure. Or at least this is what the vice president of Oracle Business Intelligence vise president Paul Rodwick claims. This new version is easier to be implemented for departmental needs and scales, offering the performance and unique scalability for the biggest and the most requesting enterprise based implementations.

Oracle Business Intelligence is the most complete, integrated and scales suite of Business Intelligence products, therefore the clients can easily obtain a better line up for the needs of their businesses and a better view on it.

This new version offers the one and only unified field from this domain, which is dedicated to accessing and analyzing the data from relational data sources, OLAP and XML. This way it enriches the user experience with a new integrated application of type scorecard and with various innovations in the modules of the report, view, searches and collaboration at an enterprise level. It also increases the performance, scalability, and security through a solid integration with Oracle Manager and the other components of Oracle Fusion Middleware.

The tablespace encryption Oracle 12c is obviously more powerful than the previous versions. It is the most complete and best-integrated infrastructure of Business Intelligence that offers extended possibilities of views.

By extending the functionalities from the Common Enterprise Information Model, 11g was the first solution that unifies technologies like Relational OLAP, Multidimensional OLAP and the enterprise based report on the same technological base. The improved possibilities of OLAP analysis allow the users to access and navigate through hierarchical data stored in Oracle Database and other relational data sources, all this by a common interface. A new thin client type integrated editor for the reports design gives the users the chance to publish both web-based interactive reports and best quality production reports, with a clearly defined format.

A new application, Oracle Score Card and Strategy Management, helps the users to follow if the parameters and key performance indicators line up with the strategy and objectives of the organization. The improved and activity oriented interface has a complete range of new filtering and creating instruments for interactive graphs, including map-based view options. Action Framework is a unique and innovating characteristic that includes the loop between understanding and taking action. This offers the users the possibility to start the action from their own board panel, like a business process or a web service.

The existing clients of Oracle Business Intelligence who use the previous version can upgrade them to the new version fast and easy, without any impact on the existing reports or metadata migration. By implementing of a database, Oracle Business Intelligence is the only available technological infrastructure in this domain that allows the system administrators to manage and monitor the sub-system performance from the same environment the whole IT suite is managed from.

Oracle Standby Database Concept

January 10, 2019 Comments off

remote dba expertsA monitoring standby database, as its name suggests, is a copy of a base of operations, held ready for use in place of the latter for availability in case of disasters and production database failure when the main base of operations has fallen and is not available. Usually, only the production data is cloned, is considered the secondary database or destination. The mechanics of implementing an emergency basis were officially available from Oracle 7. However, each new version of Oracle, the database has been waiting for a more robust and automatic. Regardless of the version, each implementation of databases expected to follow certain well-defined steps.

I have referred to the standby database and development, always within Oracle, such as the deployment of regular sleep and conventional, instead of a personalized approach described below. Based on the version, the current method to perform some steps may vary. However, the overall objective remains the same.

Refer to your version of Oracle-specific documents for details on setting up databases before, how they work, how to improve the availability, and what the relevant questions should be aware of before deciding to implement databases so out. Also, I’ve developed on the basis of some new features available in Oracle Standby and DataGuard.

Standby feature of Oracle was introduced in Oracle 7.3, so the previous version of Oracle does not provide database in standby mode. Oracle expects function is absolutely based on the changes and redo log file. Database standby function requires integrity checks inherent in the issue of the journal file and record changes in the control file.

The transactions take place in the primary database to the standby database to apply through the archive log. Archive logs are a copy of the redo logs. The transactions are written to redo log online after the process of commit, the redo logs are full, switch and stored (copied) Arch in background process. Thus, both primary and standby databases must be in ARCHIVELOG mode. Archived logs are copied to the network via a remote server in standby (either manually or automatically). In standby mode, the database is a constant state of recovery mode. All archived logs applied to copy the standby database, so that it can reach the contents of the primary database. In standby mode, the database is always behind the primary database for a few seconds.

Even if all archived logs generated to date have been implemented, which continues to lag behind, because transactions are being written at the primary online redo logs and can be applied after they are archived and copied. There are some new measures introduced to prevent this situation from Oracle 9i.

Overview on Oracle DBA Jobs

January 3, 2019 Comments off

fresher dba jobsOracle Database is a software package created and maintained by Oracle Corporation. Implementation of Oracle real application clusters (RAC) by Oracle DBA on various servers for multiple instances provides improvised performance.

Qualifications Criteria for Oracle DBA:

Oracle Database Administrator (DBA) has to qualify the training course in Oracle DBA with minimum understanding and background depth technical knowledge in computer science or information systems as Oracle is one of the most complex and sophisticated relational databases. It requires many skills learned at the college level to write and execute the commands and programs. To successfully understand the Oracle you should get trained from experts in Oracle and information systems professionals. One should be skilled in using MS SQL Server databases and have the ability to perform technical documentation and presentation professionally.

Exclusive Tips for Interview:

You should possess good communication skills and have the confidence to attend interview meeting all the requirements and skills necessary for Oracle DBA. Answer all the questions clearly without leaving any doubt. While explaining your achievements explain it to the point in a sequence of situation, task, action, and result. You should explain clearly about your past experience when asked by the interviewer. You should express willingness in doing the job.

Oracle DBA interview questions: Questions related to your strengths, weaknesses and about the changes you may bring at the workplace as an Oracle DBA are asked generally. Following are the frequently asked Oracle DBA interview questions.

  • Why do you want to be an Oracle DBA?
  • How did you get motivated to choose this for your career?
  • What contributions have you made while doing the previous job?
  • What is your long-term planning?
  • Which training courses did you complete?
  • Give an overview about Relational Database?
  • How will you work with multiple tables?
  • How do you handle errors while PL/SQL programming?
  • How can the performance be tuned in Oracle?
  • How do you backup database offline?
  • Explain about Oracle web cache and how do you start it?
  • Explain in brief about the data types in Oracle.
  • Why did you prefer our company?
  • For how many periods would you like to work for us?
  • At last, you are asked to clarify doubts, if any.

Behavior during the Interview:

You should be relaxed and make yourself comfortable throughout the interview. Express your opinion in a polite way and do not argue with the interviewer. Do not reply in a rude or harsh manner. After the interview does not forget to thank the interviewer for their time.

Work of Oracle DBA:

The Oracle DBA has to perform all the necessary activities for projects independently with less supervision. He should be expert and resolve issues of the complex database and develop solutions for DBMS tools, backup, and recovery, database performance tuning etc. He should perform migrations of database, structures, and upgrades. Oracle DBA has to maintain and utilize DBMS related procedures and standards, and know where they are located. New software and DBMS tools are to be researched, evaluated, and tested to function in accordance with the existing DBMS environment and applications. Any improvements in the current DBMS environment and its performance are monitored as per the requirements by Oracle DBA.

Always Consider Disk I/O Latency while selecting hardware for Oracle Database

January 2, 2019 Comments off

Access times seek times, rotational speed and transfer rates are more important to select storage for the database server.

disk io tuningThese questions are best asked at the end. Most vendors have this information prominently displayed on their brochures. No doubt, this information is important. However, it is far more important to understand the overall build of the I/O subsystem and make sure all the components are well balanced and balance to each other.

For instance, even if you have the fastest disk that technology and money can provide, if that disk happens to be daisy-chained to an older, slower SCSI controller, your I/O subsystem is not well balanced. No matter how proficient those disks may be, a lot of system time will be consumed in managing the controller. In other words, ensure that all the different I/O components such as your controller, disks, and channels match each other’s throughput. Your performance will be only as decent as the lowest common denominator of all these modules.

Having considered the importance of fast controllers, look at the nodes of the tree those are disks. Most 24*7 implementations deal with large databases. The sizes may not necessarily be in the terabyte range, but they are usually hundreds of gigabytes. Hence such sites find that the internal disks provided by the vendor are not adequate. There are a plethora of external disk storage array vendors. Take a hard look at what your current vendor provides. For example, Sun provides SPARC storage arrays, and HP provides the HP high availability storage systems. Most vendors are competitive in this area. If you are spending x number of dollars for your storage arrays, chances are the seek times, rotational speeds, and latencies are highly proportionate among competing vendors. In other words, latency is something that all vendors are furiously trying to reduce. Nevertheless, make a comparative study and ensure that maximum seeks times are less than 10ms, rotational speed especially for reads; write rate may be less, and average latency is less than 2.5 ms for your business applications.

Also, for configuring OLTP databases, look at seek times more closely than transfer rates. For batch and data warehousing applications, examine transfer rates more closely. This because OLTP applications involve random reads and write, where the amount of time required locating data is much more than to actually read or write it, whereas, in batch and data warehousing applications, it is the other way around. Thus, there are so many reasons to select appropriate storage hardware for your database server. If you would affect with disk I/O problems after deployment of the database then there is no chance to change it.

Oracle DBA job

February 23, 2016 Comments off

Why the Oracle DBA job is classified as a complex job

fresher dba jobsThere is a misunderstanding about what exactly the Oracle DBA profession is. Some people assume that this profession depends on technically matter only. The reality is contrasting the assumption as an Oracle DBA is forced to deal with all IT and managerial functions. An Oracle DBA has a maximum responsibility in solving all problems related to the whole of database design, database implementation, backup processes, and recovery ones. Every Oracle DBA needs to have what called excellent communication skills used to communicate with other people in solving one or more IT problems.

To note, Oracle instances are now consolidated onto large server ranging from 32 to 64 CPUs, that results in the decreasing of DBA staffs required. That is the common phenomenon of a relation between increasing technology with the amount of employers. We know background of the use of a lot of CPUs, namely multitasks to be done by DBA. An Oracle DBA needs to manage scheme design as well as other data management tasks. They get a lot of job roles.

The knowledge of Oracle database systems is not the only one needed by an Oracle DBA.

This is the base understanding. An Oracle DBA needs to combine advanced business management knowledge with database knowledge in an intention of performing database activities entirely. The Oracle DBA job needs what called college-level communication skills, formal education, real experiences (some companies requires at least 5 years of experiences), database knowledge, and so forth. The ability of explaining Oracle concepts clearly is the base preferred ability needs to have for every single prospective Oracle DBA. The master-level education degree on information systems is something can’t be compromised. Anyone who has the master-level education degree on information system is expected to solve data normalization as well as star schema design matters. Shortly, the Oracle DBA jobs run a lot of tasks.

Indeed, it is very tough job due to this reason Oracle DBA earns more. Fresher DBA is really encountering to get job and it is not so easy as you are thinking. Every technical interview is very tough and you cannot say that you cleared after finished. There are so many tricky and real time example based queries are being raised during interview. Interviewer always tries to get best candidate from high competitive market. You can get some help from

But it doesn’t mean that fresher Oracle DBA never acquire job. Using your depth knowledge and help from some senior DBA you would easily clear technical interview.

What is Reverse Key Index in Oracle?

April 19, 2014 Comments off

Reverse key indexes, as their name involves, robotically reverse the order of the bytes in the key value contained in the B-tree index. If the value in a row is ‘ABCD’, the value for the reverse key index for that row is ‘DCBA’.

To comprehend require for a reverse key index, you have to examination some basic truths about the standard B-tree index. First and primary, the depth of the B-tree is decided by the number of entries in the leaf block nodes. The greater the depth of the B-tree, the more levels of branch nodes there and the more I/O is required to locate and access the appropriate leaf block node.

reverse key indexThe new B-tree index is balanced, with an even allocation of entries across the size of the leaf pages. But some values commonly used for an index are not so well behaved. Incremental values, such as ascending sequence numbers or progressively later date values, are always inserted to the right side of the index, which is the home of higher and higher values. In addition, any deletions from the index have a tendency to be skewed toward the left side as older rows are deleted. The net effect of these practices is that over time the index turns into an unbalanced B-tree structure, where the left side of the index is more meagerly populated than the leaf nodes on the right side. This unbalanced growth has to overall effect of increasing the depth of the B-tree arrangement due to the number of entries on the right side of the index. This results described here also apply to the values that are automatically decremented, except that the left side of the B-tree will end up holding more entries.

You can resolve this issue by occasionally dropping and recreating the index or rebuild index. However, you can also resolve it by using the reverse value index, which reverse the order of the value of the index. This reversal causes the index entries to be more evenly distributed over the width of the leaf nodes. For example, rather than having the values 824,825, and 826 be added to the maximum side of the index, they are translated to the value 428, 528, and 628 for storage and then translated back when the values are regained. These values are more consistently spread throughout the leaf nodes.

The generally result of the reverse index is to correct the inequality caused by repeatedly adding increasing values to a standard B-tree index. Performance point of view, reverse key index is the best solution for gaining performance of increasing number, sequence like unique values and duplicate values both.

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