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- Oracle dba interview questions and answers
- SQL Server DBA Interview Questions and Answers
- SQL DBA Interview Questions & Answers
Oracle dba interview questions and answers
Answer: Oracle Database is a relational database management system RDBMS which is used to store and retrieve the large amounts of data. Oracle Database had physical and logical structures. Logical structures and physical structures are separated from each other. Answer :Oracle database is the collection of datafiles,redologs and control files while Oracle instance is the SGA ,processes in the Memory. We can have 1 or more instance serving a oracle database. In Oracle RAC , we have one set of datafiles,control file and redo logs while instance on one ore more boxes accesses the same database.
Question 3 What is a Tablespace? Physically, data will get stored in Datafiles. Datafiles will be connected to tablespace. A tablespace can have multiple datafiles. It contains read only data dictionary tables which contains the information about the database.
Answer: The datafiles contain all the database data. The data of logical database structures, such as tables and indexes , is physically stored in the datafiles allocated for a database. Answer: Every Oracle database has a control file. A control file contains entries that specify the physical structure of the database such as Database name and the Names and locations of datafiles and redo log files.
Answer The primary function of the redo log is to record all changes made to data. If a failure prevents modified data from being permanently written to the datafiles, then the changes can be obtained from the redo log, so work is never lost. This prevents oracle from overwriting the redo log files before they have been safely archived to another location. Answer: A user account and its associated data including tables, Oracle views , indexes, clusters, sequences ,procedures, functions, triggers,packages and database links is known as Oracle schema.
Answer: Data Blocks are the base unit of logical database space. Each data block represents a specific number of bytes of database space on a disk. The data blocks can be 4 K,8 K size depending on the requirement. Question What is an Extent? Answer :Extent is a collection of Continuous data blocks, which is used for storing a specific type of information. What is a Segment? Answer: A segment is a collection of extents which is used for storing a specific data structure and resides in the same tablespace.
What is Rollback Segment? Answer: Database contain one or more Rollback Segments to roll back transactions and data recovery. What are the different type of Segments? What is archive-log and No archive log mode?
Answer: We all know that redo logs stored the redo information and redo log files are in circular fashion. Oracle Database lets you save filled groups of redo log files to one or more offline destinations, known collectively as the archived redo log.
The process of turning redo log files into archived redo log files is called archiving. The background process ARCn automates archiving operations when automatic archiving is enabled. The database starts multiple archiver processes as needed to ensure that the archiving of filled redo logs does not fall behind. No archive log means archive log are not generated and redo are overwritten. What all things are present in the shared pool?
Answer: The shared pool portion of the SGA contains three major areas: library cache contains parsed sql statements,cursor information,execution plans dictionary cache contains cache -user account information,privileges information,datafile,segment and extent information buffers for parallel execution messages control structure. What is hotbackup? Answer: If the database must be up and running 24 hours a day, seven days a week, then you have no choice but to perform inconsistent backups of the whole database.
A backup of online data files is called an online backup. Oracle table locks. You have many instances running on the same UNIX box. How can you determine which shared memory and semaphores are associated with which instance? What is Database index? Answer: A database index is a data structure that improves the speed of data retrieval operations on a database table at the cost of slower writes and increased storage space.
By default, Oracle creates B-tree indexes. Related article Oracle Indexes Question Mechanism followed by Oracle when we are taking hotbackup. Lets take the example of Oracle version What is that trace files contains and the utility used to read them?
Trace file contains the detail diagnostics of a sql statement like explain plan, physical reads, logical reads, buffer gets etc. Tkprof utility is used to convert trace file into readable format. If we want to access objects of another database from this database then we need a database link from this database to the other. What is a patch? Question 34 Which table you will query to check the tablespace space issues? Question 35 Which table u will query to check the temp tablespace space issues?
Inventory should be set in file oraInst. How to run Opatch in non interactive form. The Global Inventory is the part of the XML inventory that contains the high level list of all oracle products installed on a machine. There should therefore be only one per machine. Its location is defined by the content of oraInst. All about AWR. It is New feature in Oracle database post It Uses past block images to back out changes to a oracle database. As the name suggest, we can use this flashback database in previous time.
During normal database operation, Oracle occasionally logs past block images in flashback logs b. Oracle automatically creates, resizes and deletes flashback logs in the flash recovery area d.
DBA should be aware of flashback logs to monitor performance,to decide how much space to allocate to flash recovery area e. Allows database to be recovered to a previous time to correct problems caused by logical data corruptions,user errors Flashback database explained and limitation.
What is Leaf Block in index? The blocks above the HWM level is free blocks, they are ready to use. The blocks below the HWM level is used blocks, they are already used. What parameters are used to set parallelism in the database? Answer: Following initialization parameters are required for parallelism setup in database. What is difference between startup mount and startup nomount? Answer The system change number SCN is an ever-increasing value that uniquely identifies a committed version of the database at a point in time.
Every time a user commits a transaction Oracle records a new SCN in redo logs. Oracle uses SCNs in control files datafile headers and redo records. Every redo log file has both a log sequence number and low and high SCN. Answer A library cache lock means that a session is waiting to use or change an object definition or to use a SQL statement that another session is loading, changing or parsing, or is waiting to change or parse. This usually indicates that database object definitions are being changed regularly.
Another example is gathering statistics on an object. When statistics are gathered all references to that object in the shared pool or library cache become invalid, requiring a new hard parse for each SQL statement referencing the object.
Statistics should only be gathered when there are no active users or system activity is very low. How to take global hanganalyze dump? How do you recover the database if you lost one of the controlfile in the database? Change Init. Database recovery various cases and solution. How do you recover the database if you lost all of the controlfile in the database? Shutdown Instance abort b. If the control-file backup is available ,then restore it from backup or if you have got the controlfile information in trace using alter database backup controlfile to trace c.
Once the controlfile is created, recover database using backup controlfile. You will need to apply the redo logs to complete the recovery d, alter database open resetlogs;. We can avoid the resetlogs by using the steps below 1. After the database is mounted with restore of controlfile from backup,create a trace of the controlfile using the command below alter database backup controlfile to trace; 2.
Now take out the create controlfile statement from the trace. Recreate the controlfile using the above portion.
SQL Server DBA Interview Questions and Answers
You are at accurate place. SVR Technologies give SQL Server training online at your registered time, you can choose classes where, when, and how it accommodates you the best. Here is the top 50 objective standard model SQL Server Dba Interview questions and their answers are provided just underneath to them. We have taken complete care to provide accurate answers to all the questions. What is BCP? When does it use? BCP does not copy the structures same as source to destination.
There are a lot of opportunities from many reputed companies in the world. What purpose does the Model Database Server? The model database , as its name implies, serves as the model or template for all databases created on the same instance. If the model database is modified, all subsequent databases created on that instance will pick up those changes, but earlier created databases will not. Traces can be filtered to narrow down the transactions that are captured and reducing the overhead incurred for the trace. The trace files can be searched, saved off, and even replayed to facilitate troubleshooting.
Explore Now! These questions and answers are suitable for both freshers and experienced professionals at any level. The source data will be copied to destination through replication agents jobs. Object level technology. The source data will be copied to destination via Transaction Log backup jobs.
When would you use it?
SQL DBA Interview Questions & Answers
If you a Database Administrator and need to update DBA technical knowledge or need to prepare for a job interview? This DBA Interview Questions and Answers are basic and advance level so every one who is DBA can get more help with these database interview questions and answers tutorial and guide. A DBA is a Database Administrator, and this is the most common job that you find a database specialist doing.
Many types of database infrastructure exist, so you want to confirm that the applicant has the background that you're looking for. Look for people who mention the specific database versions they're familiar with, as well as a brief explanation of their experience level with each. What to look for:. I started with the version and worked with that for five years. Many organizations are moving from a fully on-premises infrastructure to the cloud.
Are you a Database Administrator? Need to update DBA technical knowledge or need to prepare for a job interview? What DBA activities did you to do today?
Are you prepared in attending an interview? Are you worried for job interview preparation?
SQL Interview Questions And Answers - Dronacharya
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