Internet is full of questions and queries about oracle database or DBA(database administrator) interview questions for fresher, intermediate and experienced administrator. There has been multiple blogs available on this but seems to be rather outdated with obsolete version, or not having sufficient information and reference to authentic oracle documentation.
Q. Explain how “shared server” architecture works?
Ans: The shared server architecture enables a database server to allow many client processes to share very few server processes, so the number of users that can be supported is increased. With the shared server architecture, many client processes connect to a dispatcher.
How to configure shared server architecture details can be found here.
Q. What makes up an Oracle Instance?
Ans: An Oracle instance (also known as a database instance) contains the set of Oracle Database background processes that operate on the stored data and the shared allocated memory that those processes use to do their work.
More details on Oracle Instance can be found in Oracle documentation here.
Q. What constitutes an Oracle Database?
Ans: An Oracle database server consists of a database and at least one database instance, commonly referred to as simply an instance. Because an instance and a database are so closely connected, the term Oracle database is sometimes used to refer to both instance and database. It can also be defined as Oracle Database 19c is a multi-model database that provides full support for relational data and non- relational data, such as JSON, XML, text, spatial, and graph data.
More details can be found here.
Q. What are the types of shutdown modes of an Oracle database?
Ans: There are several modes for shutting down a database: normal, immediate, transactional, and abort. Some shutdown modes wait for certain events to occur (such as transactions completing or users disconnecting) before actually bringing down the database. There is a one-hour timeout period for these events.
More details can be found here.
Q. At what stages does an instance pass while starting up?
Ans: When you start up a database, you create an instance of that database and you determine the state of the database. Normally, you start up an instance by mounting and opening the database. Doing so makes the database available for any valid user to connect to and perform typical data access operations.
For more details open the link.
Q. What is a password file and why is it needed?
Ans: Password files can be used for local or remote connections to Oracle Database. FILE specifies the password file name. SID identifies the database instance. ENTRIES sets the maximum number of entries in the password file.
More details can be found here.
Q. Who is responsible to update the indexes?
Ans: Indexes are updated with the base table operation. You are not required to update later and independently rebuild the indexes.
More details can be found here.
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