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Monday, 22 January 2018

Oracle Standby Database Concept – Quick Look

Standby database was introduced to deploy strong disaster recovery concept using Dataguard. Dataguard is a most advanced version of Oracle standby database. First, we need to quickly look at what is Oracle standby database.

A standby database, as the name implies, is a copy of a functioning database, kept ready to be used in lieu of the latter for availability during disasters and system/database failures when the functioning primary database has crashed and is unavailable. Generally, only the production database is cloned; it is referred to as secondary or the target database. The mechanics for implementing a standby database have been officially available from Oracle 7. However, with every release of Oracle, the standby database feature has been made more robust and automatic. Irrespective of the version, every standby database implementation follows certain well-defined steps.

I have referred to this standby database implementation and development provided within Oracle as the regular and conventional standby deployment as opposed to a custom approach outlined subsequently. Based on the version, the actual method for performing certain steps may differ. However, the overall objective remains the same. Refer to your version-specific Oracle documentation set for complete details on configuring standby databases, how they work, how they enhance availability, and what pertinent issues you need to be aware of prior to deciding to implement standby databases. Also, I have elaborated on some new standby database features available in Oracle version like Dataguard.

Oracle Standby feature has been introduced within Oracle 7.3, therefore the prior version of Oracle doesn’t contain standby database feature. Oracle standby feature is absolutely depending on redo changes and archive log. Standby database feature requires inherent integrity checks for archive log shipping and redo log with control file changes.

The transactions occurring in the primary database are applied to the standby database via archive log. Archive logs are a copy of redo logs. As transactions get written to the online redo logs after commit proceeding, the redo logs get full, switch, and are archived (copied) by arch background process to respective destination. Thus, both the primary and standby databases need to be in archive log mode. The archived logs are copied across the network to the remote standby server (either manually or automatic). The standby database is continuously in a state of recovery mode. All archived logs copied over are applied to the standby database to allow it to catch up with the primary database content. The standby database is always behind the primary database for few seconds. Even if all the archived logs generated thus far have been already applied, it still lags behind because transactions are currently being written to the primary’s online redo-logs and these can be applied only after they are archived and copied over. There are some new features introduced to prevent this kind of scenario from Oracle 11g and 12c.

Friday, 12 January 2018

Why oracle database is more popular?

Oracle is the shining start in computer database solution providers. Their products such as Oracle 8i, 9i up to the 12c are designed to provide effective and efficient database management solutions. A number of other solutions providers such as Microsoft with their SQL products are chasing Oracle product for a long time. But until today there is a lot of catching up to do. Oracle database has successfully produced solutions that will require minimum investment and will provide a complete database management solution. Their products are durable, trustworthy, crash free, effective, and efficient and put less load on the process and server itself.

Oracle database is more popular because it has been developed by the world’s largest and respected enterprise solution provider and software company. Until today this manufacturer has launched a series of database products and unlike most products, their products are interconnected to each other. All their previous products are compatible with every version. It is easier to manage and to upgrade to newer versions. A number of clients have appreciated this impressive feature. So in case of the upgrade of the system all the data will be transferred to the custom search queries. This is an invective that made this product very popular.

Along with improved functionality and reliability oracle products also accompany comprehensive user manuals for assistance and troubleshooting. Along with interactive help, you can use these manuals to effect in case of emergencies. Competition in the shape of SQL has also provided these manuals but surveys have proven that they are complex and sometimes confusing. This gives an edge to Oracle products. These products also ensure improved performance every time a new version hits the market. This company reacts to previous system glitches in an aggressive manner and will fix the errors with the launch of the new system.

The durability of this system is known to every large commercial and corporate company. All of the big names have adopted this solution and they also recommend this system to a number of their clients. The durability of this system leads to the improved stability and fewer crashes. Oracle also released another dynamic product with the name of Oracle EBS. Better known as the Electronic Business Solution. This is a dynamic easy to use system targeted for businesses ventures of all sizes and structures. This smart solution requires you to invest minimum amount because it can be controlled and managed by a single site.

Single site operation capability makes this system very effective and efficient. So if you have a business and you want to maintain and operate a single database system then this is the product for you. This system has challenged products such as ERP. CRM, SCM are some of the products that are offered with the new Oracle EBS. EBS will provide solutions for your business financials, human resource management, logistics, order management and transportation management requirements. All the data will be stored under new management system. The effectiveness of this system has already generated a long list of satisfied customers.

There are lots of small, medium and large businesses using Oracle for better security, too many features and stability. Day by day it becomes more popular for everyone. One reason for this popularity is Oracle database available for Linux, Unix and Windows platform. Where some of RDBMS are not available for every platform.

About hiring resources we can say that you can find out fresher, mid-range and higher experience Oracle techies everywhere. You can get remote DBA experts support too at low cost for maintaining your low budget.

Therefore, there are lots factors advocating popularity of Oracle. Maybe you are knowing more than me.

Tuesday, 10 December 2013

Oracle DBA Interview Questions

Do you think those are being needed to clear job interview? Off course yes because you have knowledge of Oracle database administration but you don’t have experience about how to face technical questions. Sometimes, interviewer is very keen in recruitment and he or she is having good technical knowledge in database administration then interview will be toughest. Sometimes, interviewer is facing any database related issue or faced any problem then obviously he or she can be expect proper solution from candidate then he or she will be asking Oracle DBA interview questions related with same issues.

  • What is SGA?
  • What are background processes?
  • What is ASM?
  • What is RAC?
  • If I will be kill SMON then what would be happening?
  • My Oracle doesn’t bring up with error out of memory how can I resolve it?  
  • What is relation between schema and Oracle user?
  • I am altering datatype of table column does synonym will be invalidated?
  • How can I recover database when datafile got corrupted?
  • Which command should need to execute for unmounting ASM disk where 3 instances are running?
  • What is command of checking last backup of RMAN?
  • How to check defragmentation in database?
  • What is the solution to remove defragmentation of tables?
  • What is the command to remove connected user from database?
  • Log file sync wait event is constantly appearing in top 5 wait event with high resource consumption in AWR report then what is the issue and how can I solve it?

You can see above Oracle DBA interview questions are very easy but some of those should need more concentration. Some of are tricky and those require more attention because you might be trapped. If any tricky question will be asked first during interview starting time and you will give wrong answer then what will be happening? First impression is last impression. You might be loose impression and chance of job too. Sometime your answer will be correct from your side but it won’t be expected by interviewer and interviewer is expecting something else answer then also you would be rejected.

Use smart technique for replying those tricky and real time scenario based Oracle DBA interview questions. If you will be act smart then you can be create good impression during technical interview or discussion. Chances of getting job become easier. 

You can find out so many technical interview related dba questions from web but all were outdated and some of having wrong answers. You should need to prepare yourself what interviewer expecting. Real time scenario based Oracle DBA interview Questions are available very rare with explanation on web. Off course, grabbing Oracle DBA job is dream of every DBAs but without proper preparation they get failure for getting job.