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1. Explain briefly about Oracle database architecture?Answer & Explanation

Oracle database is a combination of database and instance where instance is a combination of memory structures and background process which help in reading/writing data to or from the database.

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2. What is difference between oracle SID and Oracle service name?Answer & Explanation

Oracle SID is the unique name that uniquely identifies your instance/database where as the service name is the TNS alias can be same or different as SID.

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3. What is the difference between SMON and PMON processes?Answer & Explanation

SMON (System Monitor) performs recovery after instance failure, monitor temporary segments and extents; clean temp segment, coalesce free space. It is mandatory process of DB and starts by default.

PMON (Process Monitor) failed process resources. In shared server architecture monitor and restarts any failed dispatcher or server process. It is mandatory process of DB and starts by default.  ________________________________________ 

4. Which one of the below is called as Row CacheA.

Library cache B.Fixed Area/Reserved AreaC.Dictionary Cache D.Result CacheAnswer & ExplanationAnswer: Option CExplanation:Dictionary Cache is Known as Row Cache also because it holds the data as Rows instead of buffers 

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5. What are bind variables?Answer & Explanation

With bind variable in SQL, oracle can cache queries in a single time in the SQLcache area. This avoids a hard parse each time, which saves on various locking and latching resource we use to check object existence and so on.

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6. What is the difference between PGA and UGA?Answer & Explanation

When you are running dedicated server then process information stored inside the process global area (PGA) and when you are using shared server then the process

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 information stored inside user global area (UGA).

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7. How to check Oracle database version?Answer & Explanation

SQL> Select * from v$version;